Technical articles
Understanding Cbz (Benzyloxycarbonyl): Selection Logic and Practical Value of a Classical Amino Protecting Group
Understanding Cbz (Benzyloxycarbonyl): Selection Logic and Practical Value of a Classical Amino Protecting Group
1. Why Cbz Still Matters Today
Cbz (benzyloxycarbonyl, often abbreviated as Z) is one of the most classical amino protecting groups in peptide chemistry and amine-containing organic synthesis. Its importance lies in the fact that it still retains clear experimental value today: Cbz-protected amino acids and peptide intermediates are generally quite stable; the protecting group can be removed not only by classical catalytic hydrogenolysis, but also, under specific conditions, by strong acids or by more recently developed non-hydrogenative methods. In solution-phase synthesis, stepwise separation and purification, and orthogonal deprotection design, Cbz remains a common and practical choice. Relevant literature shows that Nα-carbamate-type protecting groups such as Cbz, Boc, and Fmoc have long remained among the mainstream choices in peptide chemistry not only because they are convenient to introduce and remove, but also because this mode of protection is generally more favorable for minimizing side reactions during coupling and, to some extent, helps control the risk of racemization. However, the actual level of racemization still depends on the activating reagent, additives, substrate structure, and reaction conditions, and cannot be simply attributed to Cbz itself.
The mainstream platform in modern peptide synthesis has shifted to solid-phase synthesis, and standard workflows now mainly revolve around SPPS, especially Fmoc-SPPS. A Chemical Reviews article points out that the most common α-amino protecting groups in solid-phase peptide synthesis are Fmoc and Boc. A 2024 methodological paper on Fmoc-SPPS likewise again describes solid-phase peptide synthesis as one of the current major mainstream methods for preparing research peptides and therapeutic peptides. The value of Cbz today is not to replace Fmoc, but rather to maintain a clear and independent role in solution-phase routes, intermediate stability management, and final-stage deprotection design.
Several Key Reasons Why Cbz Is Still Worth Understanding
Core Feature of Cbz | Chemical Behavior | Significance for Experimental Design |
Mature introduction methods | Amino protection can be achieved through classical routes such as Cbz-Cl, and milder alternative introduction conditions are also available | Suitable as a conventional starting strategy, and also convenient for condition comparison and scale-up optimization |
Good stability of protected substrates | Generally stable to bases and mild acidic treatment, and can tolerate Boc removal conditions | Suitable for routes that require stepwise transformations and staged purification |
Clear deprotection pathways | Under classical conditions it can be removed by catalytic hydrogenolysis; in specific cases, strong acid or Lewis acid systems may also be used | Facilitates selection of final-step conditions according to the substrate’s tolerance toward hydrogenation, acid, or Lewis acid |
Good route compatibility | Combines a certain degree of stability with removability, allowing coordination with the protection/deprotection rhythm of the overall route | Better evaluated from the perspective of how the whole route will proceed, rather than only whether a single step is convenient |
2. The Position of Cbz: Not a Mainstream Temporary Protecting Group for Solid-Phase Synthesis, but Still an Important Route-Level Protecting Group
Cbz does not occupy the same position as Fmoc and Boc. The most common α-amino protecting groups in solid-phase peptide synthesis are Fmoc and Boc, whereas Z/Cbz is more commonly encountered in solution-phase synthesis. The significance of Cbz does not lie in being the mainstream option, but in the fact that it is still well suited to solution-phase routes, staged separation and purification, and final-step deprotection design.
Cbz has been able to retain its place in practice over the long term mainly because such protected substrates are usually relatively easy to prepare, are stable under basic and mildly acidic conditions, and have well-defined deprotection pathways: they can be removed either by hydrogenolysis or, under specific conditions, by acidic or Lewis acid systems. Relevant literature also indicates that this type of carbamate α-amino protecting group is generally beneficial for reducing the risk of racemization during peptide bond formation.
The Practical Position of Cbz Among Common Amino Protecting Groups
Protecting Group | Typical Removal Method | Typical Application Scenario | Main Advantages | Key Selection Considerations |
Cbz / Z | Catalytic hydrogenolysis; can also be removed under stronger conditions such as HBr/AcOH, HF, or BBr₃ | Solution-phase peptide synthesis, routes involving staged purification, final-step or staged deprotection design | Good stability of protected substrates, mature introduction methods, multiple deprotection pathways | Conventional removal usually starts from hydrogenolysis conditions; if the molecule is not compatible with hydrogenation, acidic or Lewis acid alternatives are generally required |
Fmoc | Removed under basic conditions, commonly with secondary amine systems | Mainstream workflows in modern Fmoc-SPPS | Highly compatible with stepwise elongation on solid phase, with a high degree of standardization | Base-sensitive sites and certain base-induced side reactions require specific control |
Boc | Removed under acidic conditions | Classical Boc/Bn routes, historical solid-phase and solution-phase systems | Mature system with extensive historical experience | Repeated acid treatment is relatively harsh, and final global deprotection conditions are comparatively strong |
Alloc | Pd(0)-catalyzed removal with scavengers | Side-chain or localized orthogonal deprotection, branched assembly, cyclization design | Good orthogonality with many protection systems | Requires Pd-based conditions, and workup is more complex |
3. Introduction of Cbz: Classical Routes and Mild Alternative Conditions
The classical introduction of Cbz usually relies on the reaction of benzyl chloroformate (Cbz-Cl) with amines. For amino acids and general amine substrates, scalable methods for the preparation of N-Cbz compounds have been reported: during the addition of benzyl chloroformate, maintaining an appropriate pH with a mixed aqueous solution of sodium carbonate/sodium bicarbonate enables large-scale preparation of N-Cbz amino acids.
The introduction of Cbz is not limited to this type of basic system. A 2007 report described iodine-catalyzed N-Cbz protection: using 2 mol% iodine as the catalyst, a wide range of aromatic and aliphatic amines could be converted to their N-Cbz derivatives in methanol at room temperature. For cases in which exposure to relatively strong basic conditions is undesirable, or where milder conditions are preferred for handling amine substrates, such methods are of clear reference value.
Two Representative Strategies for Introducing Cbz
Introduction Strategy | Condition Features | More Suitable Situations | Methodological Value |
Cbz-Cl + basic/buffered system | Classical, mature, and convenient for scale-up | Conventional N-Cbz protection of amino acids and general amines; suitable when both yield and process control are important | Well suited as a starting point for route design or as a foundational process option |
Cbz-Cl + I₂-catalyzed system | Milder conditions that can avoid relatively strong basic treatment | Useful when the substrate is more sensitive to basic conditions, or when exploring alternative protection strategies | Demonstrates the tunability of Cbz installation conditions |
4. Removal of Cbz: Classical Hydrogenolysis and Non-Hydrogenative Alternative Pathways
The most classical deprotection method for Cbz is still catalytic hydrogenolysis. A Chemical Reviews article points out that Z/Cbz can be removed by catalytic hydrogenolysis during chain elongation, and can also be removed at the final deprotection stage under stronger conditions, including HBr/AcOH, TFA at elevated temperature, TFA-thioanisole, liquid HF, and BBr₃.
For most substrates that can tolerate hydrogenation, catalytic hydrogenolysis remains the most conventional and straightforward route for Cbz removal. More recent alternative methods are mainly reflected in non-hydrogenative conditions. In 2024, The Journal of Organic Chemistry reported a method for N-Cbz removal using an AlCl₃/HFIP combination. AlCl₃/HFIP provides a representative non-hydrogenative option for Cbz deprotection; a notable feature of this method is that it enables orthogonal removal of N-Cbz in the presence of O-Bn and N-Bn protecting groups.
Main Pathways for Cbz Deprotection and Their Typical Application Scenarios
Deprotection Route | Method Positioning | Typical Application Scenario | Key Selection Considerations |
Catalytic hydrogenolysis | Classical mainstream route | Suitable for most amino acids, peptides, and general amine-containing substrates that can tolerate hydrogenation conditions | If reduction-sensitive groups are present, or hydrogenation conditions are unsuitable, other deprotection methods should be considered |
Strong acid / strong Lewis acid conditions | Traditional non-hydrogenolytic deprotection route | Late-stage collective deprotection, or substrates for which hydrogenolysis conditions must be avoided | Conditions are relatively harsh, so the stability of the substrate and other protecting groups must be considered |
AlCl₃/HFIP | Recently developed non-hydrogenative deprotection method | Cases where hydrogenation is undesirable, or where benzyl protecting groups such as O-Bn / N-Bn need to be retained in the molecule | Enables selective N-Cbz removal, but substrate compatibility with Lewis acidic conditions and the HFIP medium should be evaluated |
5. Assessing the Suitability of Cbz by Research Task
Current Research Task or Experimental Focus | Suitability of Cbz | Main Reason |
Construction of solution-phase amino acid/peptide intermediates | High | Protected substrates are relatively stable, installation methods are mature, and the group is well suited to solution-phase routes |
Need for staged separation and purification, while retaining the protecting group over multiple steps | High | Cbz is well suited as a route-level protecting group in multistep solution-phase transformations |
Final-step unified deprotection by catalytic hydrogenolysis is planned | High | This matches the most classical mainstream deprotection pathway for Cbz |
Hydrogenation is inconvenient, and selective N-Cbz removal is required in the presence of O-/N-Bn groups | Medium to high (depending on the specific substrate) | AlCl₃/HFIP provides a new non-hydrogenative and orthogonal deprotection option |
Standardized stepwise elongation in Fmoc-SPPS | Low | Such methods are usually designed primarily around the Fmoc system |
Molecules that are simultaneously incompatible with hydrogenation, strong acid, and Lewis acid conditions | Low | The practical options for common Cbz deprotection become significantly restricted |
6. Product Navigation Table for Cbz Protection/Deprotection (Choose Table 1–Table 4 by Research Task)
Current Research or Experimental Goal | Recommended Table to View First | Why This Table Should Be Prioritized | Which Table to Consult Next | Guidance |
Want to first establish the basic reaction conditions for N-Cbz protection, and screen introduction reagents, bases, and reaction media | Table 1 | Table 1 brings together Cbz-Cl, Cbz-OSu, carbonate buffer bases, triethylamine, methanol, iodine, and related components, making it the most suitable starting point for building an initial Cbz installation system | Then see Table 4 | If you later want to compare the strategic differences among Cbz, Fmoc, Boc, and Alloc protection, Table 4 can be used for route-level comparison of protecting groups |
Want to optimize Cbz introduction conditions and compare the effects of strong bases, buffered bases, and milder catalytic systems on the substrate | Table 1 | Table 1 includes both classical basic introduction conditions and iodine-catalyzed or mild introduction reagents, making it suitable for condition screening and substrate compatibility comparison | Then see Table 2 / Table 3 | If the goal is to carry the installed intermediate forward to the deprotection stage, you can turn to Table 2 if hydrogenolysis will be used, or Table 3 if hydrogenolysis is to be avoided |
Want to establish classical hydrogenolytic Cbz deprotection conditions and compare hydrogenolysis with transfer hydrogenation routes | Table 2 | Table 2 focuses on palladium sources, palladium hydroxide, formic acid, ammonium formate, and related reagents, making it the core reagent table for classical Cbz removal and transfer hydrogenation deprotection | Then see Table 3 | If the substrate contains reduction-sensitive moieties or if hydrogenolysis does not provide sufficient selectivity, Table 3 can then be consulted to evaluate acidic or Lewis acid routes |
Want to remove Cbz when the use of hydrogen gas is inconvenient or hydrogenation is undesirable | Table 3 | Table 3 focuses on non-classical or non-hydrogenative deprotection conditions such as HBr/AcOH, TFA, HF, BBr3, and AlCl3/HFIP, making it most suitable for route design that avoids hydrogenolysis | Then see Table 2 | Table 2 can then be revisited to compare non-hydrogenative conditions with classical hydrogenolytic systems in terms of efficiency, selectivity, and substrate tolerance |
Want to study acidic Cbz removal, Lewis acid-mediated Cbz removal, or compare different high-intensity final deprotection conditions | Table 3 | Table 3 covers the key reagents required for traditional acidic deprotection and Lewis acid-mediated deprotection, making it suitable for final deprotection condition screening and boundary assessment | Then see Table 1 | If the goal is to connect the entire route from Cbz introduction through final deprotection, Table 1 can then be consulted to form a complete protection–deprotection experimental plan |
Want to compare the differences among Cbz, Fmoc, Boc, and Alloc in terms of introduction, removal, and route design | Table 4 | Table 4 gathers representative reagents for Fmoc, Boc, and Alloc, together with the orthogonal deprotection system for Alloc, making it the most suitable table for horizontal comparison of protecting-group strategies | Then see Table 1 / Table 2 / Table 3 | If Cbz is ultimately selected as the main route, return to Table 1 to establish installation conditions, then choose Table 2 or Table 3 depending on whether hydrogenolysis will be used |
Want to design a multi-protecting-group orthogonal strategy to achieve stepwise removal of Cbz together with Alloc / Fmoc / Boc | Table 4 | Table 4 is the most suitable for understanding the differences in deprotection logic among protecting groups, especially the orthogonality between the Alloc Pd(0)/silane system and Cbz deprotection conditions | Then see Table 2 / Table 3 | If Cbz is planned to be removed at a later stage in the orthogonal design, Table 2 or Table 3 can then be selected according to substrate properties for hydrogenolytic or non-hydrogenative removal |
Want to design a complete Cbz route around a given amine-containing substrate, following a “protect–transform–deprotect” sequence | Start with Table 1 | A Cbz route usually begins with protection installation, and Table 1 is the most suitable for determining the starting protection conditions and substrate compatibility | Then see Table 2 / Table 3, and finally Table 4 | If the substrate tolerates hydrogenolysis, prioritize linkage to Table 2; if hydrogenolysis is unsuitable, link to Table 3; if other protecting groups are also involved in the route, then use Table 4 to design the overall protection strategy |
Want to carry out a methodology study and systematically compare the performance of the same substrate under different Cbz deprotection routes | Start with Table 2 | Table 2 represents the classical mainstream route and is suitable as the standard reference system for Cbz deprotection | Then see Table 3 | Table 3 provides acidic, Lewis acid, and non-hydrogenative alternative routes, allowing a more complete methodological comparison of deprotection approaches |
Want to use Cbz as a solution-phase intermediate protecting group and evaluate whether it is worth replacing with another protecting group | Start with Table 1 | Table 1 is best suited for establishing the basic conditions for Cbz installation and retention during the protected stage | Then see Table 4 | Table 4 helps compare alternative routes based on Fmoc / Boc / Alloc, allowing judgment of which protecting group better fits the subsequent process rhythm and deprotection logic |
Summary:
1. For Cbz introduction, start with Table 1
2. For classical hydrogenolytic or transfer hydrogenation Cbz removal, start with Table 2
3. For acidic, Lewis acid, or non-hydrogenative Cbz removal, start with Table 3
4. For comparison of Cbz with Fmoc / Boc / Alloc or orthogonal strategy design, start with Table 4
Table 1 | Cbz Installation Reagents, Alternative Installation Reagents, and Supporting Bases/Media
Category | CAS No. | Aladdin Cat. No. | Name | Grade or Purity | Product Features and Applications |
Classical reaction medium for Cbz installation / medium for iodine-catalyzed installation | 67-56-1 | M433268 | Methanol | MS grade, UltraPureChrom™, UHPLC grade | A commonly used polar protic solvent that can serve as the reaction medium for amine substrates and Cbz installation reagents; also suitable for establishing and pre-scale-up screening of molecular iodine-catalyzed N-Cbz protection conditions. |
Buffering base for Cbz installation | 144-55-8 | Sodium bicarbonate | For cell culture, for insect cell culture, ≥99.5% | A mild inorganic base suitable for use with Cbz-Cl in N-Cbz protection; its buffering effect helps control reaction pH and reduces substrate damage under overly strong basic conditions. | |
Acid scavenger / organic base for Cbz installation | 121-44-8 | Triethylamine | For protein sequencing, ≥99.5% (GC), ampoule | A commonly used organic acid scavenger that can neutralize the acid generated in installation reactions using Cbz-Cl, Cbz-OSu, and related reagents, thereby enhancing amine nucleophilicity; also suitable for comparing installation efficiency under different base conditions. | |
Comparator protecting-group reagent for Cbz installation | 28920-43-6 | Fmoc chloride | For HPLC derivatization, ≥99% (HPLC) | A commonly used Fmoc installation reagent, suitable for route comparison with Cbz systems, including solution-phase installation efficiency, downstream deprotection logic, and differences in compatibility with solid-phase peptide synthesis strategies. | |
Buffering base for Cbz installation | 497-19-8 | S432763 | Sodium carbonate | Anhydrous, PharmPure™, JP, BP, Ph. Eur., NF | A commonly used inorganic base suitable for use together with sodium bicarbonate to build buffered Cbz installation systems for N-Cbz protection of amino acids or general amine substrates, as well as for scale-up condition optimization. |
Inorganic base for Cbz installation | 1310-73-2 | S431793 | Sodium hydroxide | Anhydrous, ≥98%, pellets | A relatively strong inorganic base that can be used in Cbz installation conditions requiring higher basicity; suitable for screening the effects of base strength on reaction rate, selectivity, and substrate stability. |
Catalyst for iodine-catalyzed Cbz installation | 7553-56-2 | I116351 | Iodine | Chemically pure (CP), ≥99.5% | Can be used in molecular iodine-catalyzed N-Cbz protection conditions; suitable for examining Cbz installation on amine substrates under relatively mild conditions and for methodological comparison with traditional basic systems. |
Mild Cbz installation reagent | 13139-17-8 | N-(Benzyloxycarbonyloxy)succinimide | ≥98% | An activated carbonate-type Cbz installation reagent suitable for N-Cbz protection of base-sensitive amine substrates or substrates requiring milder conditions; also convenient for comparing reaction cleanliness and operational convenience with the Cbz-Cl route. | |
Classical Cbz installation reagent | 501-53-1 | Benzyl chloroformate | ≥96%, contains 0.1% sodium carbonate as stabilizer | One of the most classical Cbz installation reagents, suitable for N-Cbz protection of amino acids, aliphatic amines, and aromatic amines; it is a core reagent for establishing Cbz protection conditions, comparing different base systems, and optimizing scale-up processes. |
Table 2 | Reagents Related to Classical Hydrogenolysis and Transfer Hydrogenation for Cbz Deprotection
Category | CAS No. | Aladdin Cat. No. | Name | Grade or Purity | Product Features and Applications |
Hydrogen donor / acidic medium for Cbz transfer hydrogenation | 64-18-6 | F433212 | Formic acid (FA) | Pharmaceutical grade, PharmPure™, ≥98% | A commonly used hydrogen donor and acidic medium for transfer hydrogenation; can be used with palladium-catalyzed systems for exploration of Cbz deprotection conditions and is also suitable for preliminary screening of relatively mild reductive deprotection systems. |
Hydrogen donor for Cbz transfer hydrogenation | 540-69-2 | Ammonium formate | Anhydrous, reagent grade, ≥97% | A commonly used hydrogen-donating salt for transfer hydrogenation; can be combined with palladium catalysts for Cbz deprotection and is suitable for establishing deprotection methods without direct use of hydrogen gas. | |
Metal source for Cbz hydrogenolysis studies / palladium source for comparing different Pd systems | 7440-05-3 | Palladium 99+ powdered | Suitable for analysis, premium grade, ≥99% | A metallic palladium source that can be used to establish or compare Pd-based Cbz hydrogenolysis/transfer hydrogenation systems; also useful as a research raw material for preparing supported palladium catalysts or screening deprotection efficiency from different palladium sources. | |
Common palladium catalyst for Cbz hydrogenolysis / research palladium source | 12135-22-7 | Palladium hydroxide | AR | Can serve as a palladium source for hydrogenolysis studies and is suitable for use with hydrogen gas or transfer-hydrogenation donor systems during screening of Cbz deprotection conditions; it can also be used to compare the deprotection activity of different palladium species. |
Table 3 | Reagents Related to Acidic, Lewis Acid, and Other Non-Hydrogenolytic Cbz Deprotection
Category | CAS No. | Aladdin Cat. No. | Name | Grade or Purity | Product Features and Applications |
Component of the HBr/AcOH acidic de-Cbz system | 64-19-7 | Acetic acid (glacial) 100% | Anhydrous, Moligand™, Ph. Eur., premium reagent, suitable for analysis, ACS | Glacial acetic acid can serve as the solvent or acidic medium in HBr/AcOH systems for establishing traditional acidic de-Cbz conditions; also suitable for comparing substrate tolerance with hydrogenolysis routes. | |
Strongly acidic final deprotection reagent / comparator acid for deprotection | 76-05-1 | Trifluoroacetic acid (TFA) | Anhydrous, ≥99% | A commonly used strong acid in peptide chemistry; can be used in high-intensity final deprotection systems and is also suitable for examining the stability and deprotection behavior of Cbz-containing molecules under stronger acidic environments in combination with thioanisole and related additives. | |
Strongly acidic final deprotection reagent | 7664-39-3 | H477381 | Hydrofluoric acid | Basic grade reagent, for preparation, 38–40% | An extremely strong acidic final deprotection reagent that can be used to evaluate final deprotection in special protecting-group systems; suitable when assessing unified cleavage conditions for simultaneous removal of Cbz and other side-chain protecting groups. |
Acidic de-Cbz reagent | 10035-10-6 | H116385 | Hydrobromic acid | AR, ~40% | One of the classical acidic reagents for Cbz removal; can be combined with glacial acetic acid to form an HBr/AcOH system for N-Cbz deprotection studies when hydrogenolysis is not used. |
Lewis acid for non-hydrogenolytic de-Cbz | 7446-70-0 | Aluminum chloride | High purity, reagent grade, ≥99% | A Lewis-acid-type deprotection reagent that can be combined with HFIP to establish non-hydrogenolytic Cbz deprotection conditions; suitable for examining selective deprotection when reducible groups are present or when metal-hydrogenation systems are inconvenient to use. | |
Reaction medium for AlCl₃/HFIP non-hydrogenolytic de-Cbz | 920-66-1 | 1,1,1,3,3,3-Hexafluoro-2-propanol | For GC derivatization, ≥99.8% | A fluorinated alcohol reaction medium that can be combined with AlCl₃ to establish non-hydrogenolytic de-Cbz conditions; suitable for examining selective N-Cbz removal while avoiding hydrogenation and retaining benzyl-type protecting groups such as O-Bn and N-Bn. | |
Strong Lewis acid de-Cbz reagent | 10294-33-4 | B123886 | Boron tribromide | PrimorTrace™, ≥99.99% metals basis | A strong Lewis acid that can be used to explore more forceful deprotection conditions; suitable for examining the removal behavior of Cbz and related benzyl-type protecting groups under strong Lewis acidic conditions. |
Scavenger / auxiliary reagent for strong-acid final deprotection | 100-68-5 | Methyl phenyl sulfide | ≥99% | Also known as thioanisole; can serve as a scavenger or auxiliary component in strong-acid final deprotection systems and is suitable for use with TFA and related acids in establishing high-intensity deprotection conditions and studying suppression of side reactions. |
Table 4 | Reagents Related to Comparator Protecting Groups and Orthogonal Protection Strategies
Category | CAS No. | Aladdin Cat. No. | Name | Grade or Purity | Product Features and Applications |
Catalyst for Alloc orthogonal deprotection | 14221-01-3 | Tetrakis(triphenylphosphine)palladium(0) | Pd ≥8.9% | A classical Alloc deprotection catalyst, suitable for comparison with Cbz systems in orthogonal protection strategies and commonly used to examine stepwise deprotection plans involving multiple protecting groups. | |
Common base for Fmoc deprotection | 110-89-4 | P1506301 | Piperidine | AR, ≥99.5% | One of the most commonly used bases for Fmoc deprotection; suitable for comparison with Cbz protection routes when evaluating differences in deprotection cadence and process logic among different α-amino protecting groups. |
Comparator protecting-group installation reagent for Boc | 24424-99-5 | Di-tert-butyl dicarbonate | ≥99% | A classical Boc installation reagent, suitable for comparing protecting-group selection with Cbz installation conditions and also commonly used for establishing different protection strategies for solution-phase and solid-phase precursors. | |
Comparator protecting-group installation reagent for Alloc | 2937-50-0 | A151782 | Allyl Chloroformate | ≥98% | An Alloc protecting-group installation reagent, suitable for orthogonal protection design comparisons with Cbz, Boc, and Fmoc in route construction requiring staged local deprotection. |
Supporting hydrogen source / scavenger for Alloc orthogonal deprotection | 694-53-1 | Phenylsilane | ≥97% (GC) | Commonly used with Pd(0) systems for Alloc deprotection; suitable for establishing orthogonal deprotection conditions parallel to Cbz and for comparing the stepwise deprotection operability of different protecting-group systems. |
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 No./catalog number.
References
1.Isidro-Llobet A, Alvarez M, Albericio F. Amino acid-protecting groups. Chemical Reviews. 2009;109(6):2455-2504. DOI: 10.1021/cr800323s.
2.Pehere AD, Abell AD. An improved large scale procedure for the preparation of N-Cbz amino acids. Tetrahedron Letters. 2011;52(13):1493-1494. DOI: 10.1016/j.tetlet.2011.01.102.
3.Varala R, Enugala R, Adapa SR. Molecular iodine-catalyzed efficient N-Cbz protection of amines. Journal of the Iranian Chemical Society. 2007;4(3):370-374. DOI: 10.1007/BF03245988.
4.Vinayagam V, Sadhukhan SK, Botla DV, et al. Mild Method for Deprotection of the N-Benzyloxycarbonyl (N-Cbz) Group by the Combination of AlCl₃ and HFIP. The Journal of Organic Chemistry. 2024;89(8):5665-5674. DOI: 10.1021/acs.joc.4c00177.
5.Hansen PR, Oddo A. Fmoc Solid-Phase Peptide Synthesis. Methods in Molecular Biology. 2024;2821:33-55. DOI: 10.1007/978-1-0716-3914-6_3.
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