The Core Value of the Trityl Family of Protecting Groups: Acid-Deprotection Hierarchies and Selective Route Design

Introduction

 

In protecting-group chemistry, trityl (Trt) and its substituted derivatives—such as 4-methyltrityl (Mtt), 4-methoxytrityl (Mmt), and 4,4′-dimethoxytrityl (DMTr)—are often simply regarded as “several closely related acid-labile protecting groups.” From the standpoint of experimental route design, however, that understanding is still incomplete. Their real importance lies in the fact that introducing substituents changes the acid-deprotection sensitivity of the trityl scaffold, thereby creating a usable hierarchy of acid lability. As a result, “when to deprotect, which group to remove first, and to what extent deprotection should proceed” become designable steps.

 

In peptide chemistry, this is reflected in the stepwise release of side chains such as those of histidine (His), lysine (Lys), ornithine (Orn), and cysteine (Cys). In nucleoside and oligonucleotide chemistry, it is reflected in the efficient protection of the 5′-hydroxyl group by DMTr, as well as in the DMTr-on strategies that subsequently developed for purification and process monitoring.

 

Precisely because different trityl derivatives provide a usable hierarchy of acid deprotection, researchers can schedule side-chain release, subsequent chain extension, cyclization, or site-specific modification at different stages of a synthesis. The trityl family is therefore not merely a collection of similar acid-labile protecting groups, but rather a set of acid-deprotection tools that can support orthogonal route design.

 

1. The Defining Feature of the Trityl Family: Graded, Usable Selectivity in Acid Deprotection

 

A shared feature of trityl-type protecting groups is that they can be removed under acidic conditions, while substituents on the aromatic rings alter how readily deprotection occurs. Accordingly, the differences among Trt, Mtt, and Mmt should not be understood simply as the fact that they all belong to the category of acid-labile protecting groups; instead, they should be understood as a usable hierarchy of acid lability built on the same trityl framework. In general, Trt is usually more stable than Mtt and Mmt; both Mtt and Mmt are more acid-labile derivatives of Trt, and Mmt is often more readily removed than Mtt. For this reason, Trt is better suited to sites that need to remain protected until a later stage or be removed together during final global acid treatment, whereas Mtt and Mmt are better suited to tasks that require site-specific side-chain release during the course of synthesis. This deprotection window is not an absolute constant; in practice, it is still influenced by factors such as substrate structure, resin type, and the composition of the acidic system.

 

The practical significance of this difference lies in route planning. Sites that need to remain protected until a late stage, or that are intended to be removed only during final global acid treatment, are more suitably assigned relatively stable protecting groups. By contrast, sites that need to be released partway through a synthesis so that branching, cyclization, ligation, or post-modification can then proceed are better matched with protecting groups that can be removed more readily and selectively.

Several Methodologically Important Protecting Groups in the Trityl Family

 

Protecting Group	Commonly Protected Targets	Typical Mode of Use	Value Worth Noting
Trt	His, Cys, and certain acid-sensitive side-chain sites	Better suited to being retained until a late stage or removed together during global acid treatment	Used as a relatively stable trityl-type protecting group
Mtt	Side-chain sites such as Lys and Orn that need to be released during the synthesis; also used for some temporary side-chain protection	Suitable for site-specific deprotection on resin followed by continued extension, branching, or cyclization	Makes it possible to “unmask the side chain first, then continue main-chain synthesis”
Mmt	Sites requiring milder and more selective release, commonly in certain Cys-related applications	Suitable for local deprotection under lower acid strength	Provides milder conditions for site-specific acid deprotection
DMTr	5′-hydroxyl groups of nucleosides/oligonucleotides	Used for 5′-OH protection; can also be retained for DMT-on separation	Enables the protecting group to serve simultaneously in protection, separation, and process monitoring

 

2. Key Value in Peptide Chemistry: Controlling When Side Chains Are Released

 

2.1 Two Core Uses of the Trityl Family in Peptide Chemistry

 

Application Scenario	Common Choice	Key Reason
Protection of the His side chain in conventional Fmoc/tBu synthesis	Trt	It can withstand standard chain-elongation conditions and be removed during final strong-acid global deprotection, and has therefore long been one of the common choices for His side-chain protection
Cases where a specific side-chain site needs to be released selectively during synthesis	Mtt, Mmt	They are more acid-labile than Trt and are therefore better suited to local deprotection while other acid-sensitive protecting groups and the resin linkage remain intact, enabling branching, cyclization, or post-modification

 

Within the Fmoc/tBu strategy, the significance of His side-chain protection is not only to suppress side reactions involving the imidazole ring, but also to reduce racemization during coupling as much as possible. Trt remains one of the most commonly used protecting groups for the histidine side chain in Fmoc-SPPS, because it is compatible with standard Fmoc chemistry, remains stable during chain elongation, and is removed together during the final strong-acid treatment.

 

However, the role of His(Trt) should be understood as reducing risk rather than eliminating it fundamentally. In His(Trt), the Nπ position, which is more directly associated with racemization, is not directly blocked. Therefore, His(Trt) can reduce but cannot eliminate the risk of racemization during coupling; its actual performance is still strongly influenced by the activation method, pre-activation time, and overall process conditions. A 2022 process study also made it clear that coupling of Fmoc-His(Trt)-OH in solid-phase peptide synthesis is often accompanied by substantial racemization. Thus, in His coupling, the choice of protecting group must still be considered together with activation and process optimization.

 

Unlike Trt, Mtt and Mmt are better suited to the task of “site-specific deprotection at an intermediate stage.” Because they can be removed more readily than Trt under milder acidic conditions, they are more suitable in Fmoc-SPPS as temporary side-chain protecting groups that allow one specific side-chain site to be unmasked first, followed by branching, cyclization, or site-specific modification. The methodological value of this approach was directly illustrated by the 1998 work of Matysiak and co-workers. That study directly evaluated the use of the more acid-labile monomethoxytrityl (Mmt) and dimethoxytrityl (Dmt) protecting groups in Fmoc solid-phase peptide synthesis, with a particular focus on achieving selective detritylation while other acid-sensitive protecting groups remained intact, thereby supporting multibranch construction, cyclization, and post-assembly site modification.

 

2.2 Logic for Choosing Trt, Mtt, and Mmt in Peptide Synthesis

 

Current Task	Protecting Group Better Considered First	Key Selection Point
The side chain should remain protected until completion of the main chain and then be removed together at the end	Trt	Relatively more stable and suitable for removal together during final strong-acid treatment after standard chain elongation
One side-chain site needs to be released first on resin, followed by branching, cyclization, or coupling modification	Mtt	Can serve as a temporary side-chain protecting group and is suitable for site-specific deprotection at an intermediate stage
Site-specific release needs to be easier than with Mtt and possible under milder conditions	Mmt	More acid-labile than Trt and can be removed selectively under milder acidic conditions
Conventional protecting-group choice for the His side chain	Trt	Still one of the most commonly used His protecting groups in the Fmoc/tBu strategy
Racemization is the main concern during His coupling	One cannot look only at the protecting group; activation and process conditions must also be optimized in parallel	His(Trt) can reduce but not eliminate the risk of racemization; the actual outcome is still affected by the activation method, pre-activation time, and overall process conditions

 

3. The Key Value of DMTr in Nucleoside and Oligonucleotide Chemistry: 5′-Hydroxyl Protection, Separation, and Process Monitoring

 

Function	Specific Manifestation	Methodological Value
5′-Hydroxyl protection	Used as a common 5′-OH protecting group in nucleoside/oligonucleotide chemistry	Facilitates chain elongation and is compatible with standard oligonucleotide synthesis workflows
Purification aid	Full-length products retaining 5′-DMTr can be separated from failure sequences on RP-HPLC because of their greater hydrophobicity	Makes it easier to distinguish full-length products from truncated sequences
Process monitoring	Quantification via the absorption of the DMTr cation at 504 nm	Can be used to estimate synthesis yield and monitor the synthetic process

 

In nucleoside and oligonucleotide chemistry, DMTr is one of the most commonly used trityl-type protecting groups for the 5′-hydroxyl group. The 2024 update in Current Protocols continued to focus on methods for 5′-hydroxyl protection and treated DMTr-related strategies as an important topic, indicating that DMTr remains one of the core protecting approaches in oligonucleotide synthesis.

 

The methodological value of DMTr lies not only in protecting the 5′-hydroxyl group, but also in its direct role in separation and monitoring. A 2025 review on purification handles for oligonucleotide separation pointed out that, after solid-phase oligonucleotide synthesis, the crude product typically contains both full-length sequences and truncated failure sequences. In the DMTr-on mode, full-length products that retain the 5′-DMTr group can be separated more readily from failure sequences on RP-HPLC because of their greater hydrophobicity. The review also noted that, in DMTr-on synthesis, the absorption of the DMTr cation at 504 nm can be used for quantification, thereby allowing estimation of the synthesis yield of the target oligonucleotide.

 

In oligonucleotide chemistry, the core roles of DMTr are mainly reflected in three aspects: protection of the 5′-hydroxyl group, assistance in purification, and support for process monitoring. This differs from the roles of Trt, Mtt, and Mmt in peptide chemistry, where they mainly serve in stepwise acid deprotection, and it also highlights the additional value of DMTr in separation and process control.

 

4. Three Lessons This Family Offers for Protecting-Group Development, from Trt to DMTr

 

Development Insight	Specific Manifestation	Significance for Experimental Design
Protecting-group development is not simply about pursuing “easier removal”	The differentiation of Trt, Mtt, and Mmt shows that the same scaffold can be assigned different tasks according to different release timings	Before selecting a protecting group, one should first define when the target site is intended to be released
Protecting groups can also serve downstream process functions	DMTr not only protects the 5′-hydroxyl group, but can also be used for DMTr-on purification and 504 nm quantification	Protecting-group selection should not focus only on the reaction step itself; separation and monitoring should also be incorporated into the design
What truly requires optimization is the combination of “protecting group + process conditions”	Significant racemization can still occur with His(Trt), and the outcome depends on the activation method and pre-activation time	The name of the protecting group itself cannot substitute for process optimization; screening should be carried out at the level of the overall system

 

5. Product Navigation for the Trityl Family of Protecting Groups (Choose Tables 1–4 According to Research Task)

 

Current Research or Experimental Goal	Recommended Table to Consult First	Why This Table Should Be Consulted First	Suggested Additional Table(s) to Consult	Navigation Notes
Want to first understand which reagents are used to introduce Trt, Mtt, Mmt, and DMTr protecting groups	Table 2	Table 2 brings together Trt-Cl, Mtt-Cl, Mmt-Cl, DMT-Cl, and more highly methoxy-substituted trityl chlorides, making it the starting point for understanding protecting-group sources and installation strategies	Table 3 / Table 4	For amino acid side-chain protection, then consult Table 3; for nucleoside or oligonucleotide work, then consult Table 4.
Want to compare the acid-lability differences among Trt, Mtt, and Mmt and establish selective deprotection or detritylation conditions	Table 1	Table 1 focuses on key reagents and media for deprotection conditions, including TFA, DCM, AcOH, TFE, HFIP, BF3·Et2O, CAN, and Et3SiH	Table 3	If the goal is practical operation on amino acid side chains such as His, Cys, Lys, or Orn, Table 3 can then be consulted to match conditions with specific monomers.
Want to choose side-chain protecting groups for His, Cys, Asn, and Gln in Fmoc-SPPS	Table 3	Table 3 centers on Fmoc-His(Trt)-OH, Fmoc-Cys(Trt)-OH, Fmoc-Asn(Trt)-OH, Fmoc-Gln(Trt)-OH, as well as the more acid-labile Mtt/Mmt monomers, making it the most relevant to peptide-building-block selection	Table 1	First identify the monomer in Table 3, then consult Table 1 for the corresponding deprotection range and condition pairing.
Want to carry out site-specific intermediate-stage deprotection of Lys or Orn side chains for branched peptides, side-chain extension, fluorescent labeling, or lipidation	Table 3	The Lys(Mtt), Lys(Mmt), and Orn(Mtt) entries in Table 3 are precisely the most common entry-point monomers for this type of “temporary side-chain protection”	Table 1	When releasing ε-amino or δ-amino groups at an intermediate stage, Table 1 should also be consulted to screen low-percentage TFA or fluoroalcohol-based systems.
Want finer stepwise control at a Cys site, such as first unmasking the thiol on resin and then performing cyclization, bridge formation, or post-modification	Table 3	Table 3 lists the three representative monomer types Cys(Trt), Cys(Mtt), and Cys(Mmt), making it most suitable for comparing Cys protection strategies under different acid-deprotection ranges	Table 1	First use Table 3 to determine the protection hierarchy, then use Table 1 to choose more suitable deprotection conditions.
Want to enter DMTr chemistry from the perspective of nucleoside intermediates or phosphoramidite monomers and carry out DNA/oligonucleotide synthesis	Table 4	Table 4 focuses on DMTr-protected nucleoside intermediates and DMT-dA, dC, dG, and dT phosphoramidite building blocks, making it the most direct product entry point for oligonucleotide work	Table 2 / Table 1	To return to the introduction reagents for DMTr, consult Table 2; to understand subsequent detritylation or DMTr-on-related operations, also consult Table 1.
Want to start from the most basic DMTr-protected intermediates of thymidine, deoxyadenosine, deoxycytidine, and deoxyguanosine and continue derivatization independently	Table 4	Table 4 contains not only ready-to-use phosphoramidite monomers, but also DMTr-protected nucleoside intermediates suitable for route development or intermediate preparation	Table 2	If you need to return to the origin and structural comparison of DMTr protection itself, then consult Table 2.
Want to study mild detritylation, alternatives to strong-acid deprotection, or non-classical detritylation conditions	Table 1	The HFIP, TFE, BF3·Et2O, CAN, and Et3SiH entries in Table 1 are suitable for this type of condition development and comparison	Table 2 / Table 3	If you want to connect condition development to specific protecting-group structures, consult Table 2; if you want to connect it to peptide monomers, consult Table 3.
Want to compare the experimental positioning of Trt, Mtt, Mmt, and DMTr from the perspective of protecting-group structural differences	Table 2	Table 2 most directly presents the structural hierarchy of different trityl introduction reagents and is the foundation for understanding differences in acid lability and application	Table 1 / Table 3 / Table 4	After reviewing Table 2, you can then move to Table 1, Table 3, or Table 4 according to your research direction, focusing respectively on deprotection conditions, peptide monomers, or oligonucleotide building blocks.
Want to quickly determine whether your work is oriented more toward peptide chemistry or toward nucleoside/oligonucleotide chemistry	Table 3 / Table 4	Table 3 corresponds to the main applications of Trt/Mtt/Mmt in amino acid side-chain protection and Fmoc-SPPS; Table 4 corresponds to the main applications of DMTr in nucleoside and oligonucleotide synthesis	Table 1 / Table 2	After identifying the direction, return to Table 1 to screen deprotection conditions, or consult Table 2 to understand the sources of protecting-group introduction.

 

Table 1 | Reagents and Media Related to Trt / Mtt / Mmt Deprotection and Selective Detritylation

 

Category	CAS No.	Aladdin Catalog No.	Name	Specification or Purity	Product Features and Applications
Auxiliary acid source for selective acid deprotection	64-19-7	A116166	Acetic acid	GR, ≥99.5%	Commonly used as a weakly acidic medium or auxiliary acid source to tune the selective removal conditions of more labile trityl protecting groups such as Mtt and Mmt; it can also serve as an acidic component in fluoroalcohol-based systems.
Fluoroalcohol medium for mild detritylation	920-66-1	H107503	1,1,1,3,3,3-Hexafluoro-2-propanol	For GC derivatization, ≥99.8%	A highly polar fluoroalcohol that can be combined with Lewis acids or silane systems to achieve milder O/N/S-trityl deprotection; also often used to reduce substrate exposure to strong acid.
Common solvent for selective acid deprotection	75-09-2	D433565	Dichloromethane	Anhydrous, ≥99.8%, containing 40–150 ppm amylene as stabilizer	A classic organic solvent commonly combined with low-percentage TFA to form selective Mtt/Mmt deprotection systems; also used as a washing solvent and reaction medium after removal of Trt-type protecting groups.
Main reagent for global acid deprotection	76-05-1	T433655	Trifluoroacetic acid (TFA)	Anhydrous, ≥99%	One of the most commonly used acid deprotection reagents; suitable for global deprotection at the end of peptide synthesis and also for rapid removal of Trt, Mtt, and Mmt protecting groups. By lowering its proportion, milder and more selective side-chain release can be achieved.
Lewis-acid-type detritylation reagent	109-63-7	B431395	Boron trifluoride diethyl etherate	Suitable for synthesis	A commonly used Lewis acid that can enable relatively mild removal of certain O-/N-/S-trityl protecting groups and is suitable for exploring detritylation conditions that avoid conventional strong acids.
Oxidative detritylation reagent	16774-21-3	A485845	Ammonium cerium(IV) nitrate	Ph. Eur., suitable for analysis, ACS, premium grade	A commonly used oxidant that can be explored for oxidative deprotection of certain tritylated substrates, making it useful in cases where conventional strong-acid conditions need to be avoided.
Fluoroalcohol cosolvent for selective deprotection	75-89-8	T109511	2,2,2-Trifluoroethanol	Molecular biology grade, ≥99.8%	A fluoroalcohol cosolvent commonly used in combination with AcOH, DCM, and related systems for selective removal of Mtt and Mmt side-chain protecting groups, helping balance solubility and mildness.
Triarylmethyl cation scavenger / hydrogen source	617-86-7	T106570	Triethylsilane (NSC 93579)	≥98%	Commonly used as a triarylmethyl cation scavenger or hydrogen source; when combined with TFA or Lewis acids, it can reduce retritylation and side reactions, improving the cleanliness of deprotection.

 

Table 2 | Trt / Mtt / Mmt / DMTr Introduction Reagents

 

Category	CAS No.	Aladdin Catalog No.	Name	Specification or Purity	Product Features and Applications
More highly methoxy-substituted trityl introduction reagent	49757-42-8	T476899	4,4′,4′′-Trimethoxytrityl chloride	Industrial grade	A triarylmethylating reagent with a higher degree of methoxy substitution; the protecting groups formed from it are generally more readily removed under acidic conditions, making it suitable for temporary-protection designs requiring higher acid lability.
4-Methyltrityl introduction reagent	23429-44-9	C192210	4-Methyltrityl chloride	≥98%	Used to introduce the 4-methyltrityl protecting group; commonly employed in strategies requiring site-specific intermediate-stage deprotection of side chains, offering a balance between stability and a more flexible acid-deprotection range than Trt.
4,4′-Dimethoxytrityl introduction reagent	40615-36-9	D109292	4,4′-Dimethoxytrityl chloride (DMT-Cl)	≥97%	Used to construct the DMTr protecting group; a classical reagent for 5′-OH protection in nucleosides, and also commonly used in workflows that take advantage of DMTr-on behavior for purification and monitoring.
4-Methoxytrityl introduction reagent	14470-28-1	M113503	4-Monomethoxytrityl chloride	≥97%	Used to introduce the 4-methoxytrityl protecting group; the resulting protecting group is generally more acid-labile than Mtt and is suitable for milder stage-specific release.
Trityl introduction reagent	76-83-5	T106184	Trityl chloride	≥97%	A classical tritylating reagent used to construct relatively stable acid-labile protecting groups; widely used in the preparation of protected monomers or intermediates for sites such as His, Cys, Asn, and Gln.

 

Table 3 | Common Trt / Mtt / Mmt Side-Chain-Protected Amino Acid Monomers in Peptide Chemistry

 

Category	CAS No.	Aladdin Catalog No.	Name	Specification or Purity	Product Features and Applications
Cys side-chain Mmt-protected monomer	177582-21-7	F167976	Fmoc-S-(4-Methoxytrityl)-L-cysteine	≥98% (HPLC), ~ca. 11% dioxane	Used in Fmoc-SPPS to introduce a thiol protecting group that can be released more mildly; suitable for on-resin site-specific exposure of the Cys side chain followed by cyclization, disulfide-bond formation, or site-specific modification.
Cys side-chain Mtt-protected monomer	269067-38-1	F350456	Fmoc-S-4-methyltrityl-L-cysteine	≥98%	Provides an acid-deprotection range intermediate between Trt and Mmt, making it suitable for applications requiring stepwise control over Cys side-chain release.
Cys side-chain Trt-protected monomer	103213-32-7	F100409	Fmoc-Cys(Trt)-OH	≥98%	A classical Cys side-chain-protected monomer, suitable for keeping the thiol stably protected until a late stage or until global deprotection.
His side-chain Mmt-protected monomer	133367-33-6	F116830	Fmoc-His(MMt)-OH	≥98%	Suitable for Fmoc-SPPS designs that require earlier release of the imidazole side chain than His(Trt), and can be used for stepwise modification or site-selective operations.
His side-chain Trt-protected monomer (Boc route)	32926-43-5	B116701	Boc-His(Trt)-OH	≥98%	A commonly used His side-chain-protected monomer for the Boc route; Trt can be removed during strong-acid workup, making it suitable for classical solution-phase or solid-phase routes.
His side-chain Trt-protected monomer (Fmoc route)	109425-51-6	F116780	Fmoc-His(Trt)-OH	≥98%	One of the most classical His monomers in Fmoc-SPPS, balancing side-chain protection with compatibility with standard synthetic workflows.
Asn side-chain Trt-protected monomer	132388-59-1	F110976	Fmoc-Asn(Trt)-OH	≥97%	Used to protect the Asn side-chain amide and reduce side-chain participation in side reactions; suitable for the stable incorporation of asparagine residues in Fmoc-SPPS.
Lys side-chain Mmt temporary-protection monomer	159857-60-0	N349325	Fmoc-Lys(Mmt)-OH	≥95%	Used to temporarily protect the ε-amino group in Fmoc-SPPS; it can be removed first under relatively low acidity, facilitating subsequent branching, fluorescent labeling, lipidation, or cyclization.
Gln side-chain Trt-protected monomer	132327-80-1	F110977	Fmoc-Gln(Trt)-OH	≥95%	Used to protect the Gln side-chain amide, making it suitable for keeping the glutamine side chain stably protected until a late-stage deprotection step.
Lys side-chain Mtt temporary-protection monomer	167393-62-6	F116838	N^a-Fmoc-N^e-(4-methyltrityl)-L-lysine	≥95%	Commonly used for intermediate-stage, site-specific release of the ε-amino group; suitable for side-chain extension, tag conjugation, and branched-peptide construction.
Orn side-chain Mtt temporary-protection monomer	343770-23-0	F183859	Fmoc-Orn(Mtt)-OH	≥95%	Used for temporary protection of the Orn side-chain amine, facilitating side-chain extension, ligation, or cyclization after main-chain assembly.

 

Table 4 | DMTr-Protected Nucleoside Intermediates and Phosphoramidite Building Blocks for Oligonucleotide Synthesis

 

Category	CAS No.	Aladdin Catalog No.	Name	Specification or Purity	Product Features and Applications
DNA synthesis phosphoramidite monomer (dA)	98796-53-3	D120143	DMT-dA(Bz) Phosphoramidite	≥99%, mixture of isomers	A standard dA building block commonly used in solid-phase DNA synthesis; the 5′-OH is protected by DMTr, and the 3′ position carries the coupling-active phosphoramidite, making it suitable for automated oligonucleotide assembly.
DMTr-protected nucleoside intermediate (dG)	68892-41-1	I119519	N2-Isobutyryl-5′-O-(4,4′-dimethoxytrityl)-2′-deoxyguanosine	≥99%	A common DMTr-protected nucleoside intermediate that can be further converted into the corresponding phosphoramidite or other oligonucleotide synthesis building blocks.
DNA synthesis phosphoramidite monomer (dG, Ib-protected)	93183-15-4	D120145	DMT-dG(Ib) Phosphoramidite	≥99%	One of the standard dG building blocks commonly used in solid-phase DNA synthesis, suitable for automated oligonucleotide chain elongation.
DNA synthesis phosphoramidite monomer (dT)	98796-51-1	D120146	DMT-dT Phosphoramidite	≥99%	A standard dT building block commonly used in solid-phase DNA synthesis; the 5′-DMTr group facilitates protection and monitoring during coupling cycles.
DMTr-protected nucleoside intermediate (dC)	67219-55-0	B119471	N4-Benzoyl-5′-O-(4,4′-dimethoxytrityl)-2′-deoxycytidine	≥99%	A common DMTr-protected dC intermediate, suitable for further preparation of the corresponding phosphoramidite or other oligonucleotide synthesis precursors.
DMTr-protected nucleoside intermediate (dA)	64325-78-6	B119470	N6-Benzoyl-5′-O-(4,4′-dimethoxytrityl)-2′-deoxyadenosine	≥99%	A common DMTr-protected dA intermediate that can be used to further prepare the corresponding oligonucleotide synthesis building blocks.
DMTr-protected nucleoside intermediate (dT)	40615-39-2	O117684	5′-O-(4,4′-Dimethoxytrityl)thymidine	≥98%	One of the most basic DMTr-protected thymidine intermediates, commonly used as a starting point for further preparation of dT phosphoramidites or other derivatives.
DNA synthesis phosphoramidite monomer (dC, Ac-protected)	154110-40-4	B299951	DMT-dC(Ac) Phosphoramidite	≥98%	One of the standard dC building blocks commonly used in solid-phase DNA synthesis, suitable for routine automated oligonucleotide assembly.
DNA synthesis phosphoramidite monomer (dG, dmf-protected)	330628-04-1	B300766	DMT-dG(dmf) Amidite	≥98%	A dG phosphoramidite building block bearing dmf protection, suitable for standard solid-phase DNA synthesis workflows and usable as another common choice for dG monomers.

 

Note: The products listed above are representative Aladdin products. For more product specifications, please refer to the product list at the end of the article or search the Aladdin website using the “product name / CAS / catalog number.”

 

References

 

[1] Isidro-Llobet A, Álvarez M, Albericio F. Amino acid-protecting groups. Chemical Reviews. 2009;109(6):2455-2504. doi:10.1021/cr800323s.

 

[2] Sieber P, Riniker B. Protection of histidine in peptide synthesis: A reassessment of the trityl group. Tetrahedron Letters. 1987;28(48):6031-6034. doi:10.1016/S0040-4039(00)96856-4.

 

[3] Matysiak S, Böldicke T, Tegge W, Frank R. Evaluation of monomethoxytrityl and dimethoxytrityl as orthogonal amino protecting groups in Fmoc solid phase peptide synthesis. Tetrahedron Letters. 1998;39(13):1733-1734. doi:10.1016/S0040-4039(98)00055-0.

 

[4] Yang Y, Hansen L, Baldi A. Suppression of simultaneous Fmoc-His(Trt)-OH racemization and Nα-DIC-endcapping in solid-phase peptide synthesis through design of experiments and its implication for an amino acid activation strategy in peptide synthesis. Organic Process Research & Development. 2022;26(8):2464-2474. doi:10.1021/acs.oprd.2c00144.

 

[5] Seliger H, Sanghvi YS. An update on protection of 5′-hydroxyl functions of nucleosides and oligonucleotides. Current Protocols. 2024;4(3):e999. doi:10.1002/cpz1.999.

 

[6] Fuchi Y, Hari Y. Recent advances related to purification handles for oligonucleotide separation. Tetrahedron Letters. 2025;173:155853. doi:10.1016/j.tetlet.2025.155853.

 

For more related articles, please see below:

 

Protection Reagents

 

Functional group protection and deprotection in oligonucleotide synthesis