Benzyloxycarbonyl group

The reactivity of an ammo group is suppressed by converting it to an amide and ammo groups are most often protected by acylation The benzyloxycarbonyl group O... 

Lysine reacts with two equivalents of benzyloxycarbonyl chio ride to give a derivative containing two benzyloxycarbonyl groups What is the structure of this compound /... 

Just as It IS customary to identify individual ammo acids by abbreviations so too with protected ammo acids The approved abbreviation for a benzyloxycarbonyl group IS the letter Z Thus N benzyloxycarbonylphenylalanine is represented as... 

Another name for the benzyloxycarbonyl group is carbobenzoxy This name and Its abbreviation Cbz are often found in the older lit erature but are no longer a part of lUPAC nomenclature... 

The conversion of 3 to 8 is summarized in Scheme 2. The trityl group (too large and too acid sensitive for the ensuing steps) was removed from N, and both N s were protected by Cbz (benzyloxycarbonyl) groups. Protection of the tertiary OH specifically as the robust TBS (f-butyldimethylsilyl) group was found to be necessary for the sequence involving the electrophilic aromatic substitution step, 5 to 6, and the Stille coupling steps (6 + 7 —> 8). 

Since the use of N,iV-dimethylacetamide and triethylamine improved the rate and extent of cleavage of the JV-benzyloxycarbonyl group in several difficult cases, these additives have been incorporated into the submitters standard procedure and are included in the present procedures. Deprotection with this method has been carried out with as much as 25 g. of the protected peptide. 

A -Benzyloxycarbonyl groups, catalytic hydrogenolysis in sulfur-containing peptides, 59, 166... 

Removal of N -Benzyloxycarbonyl Groups from Sulfur-Containing Peptides BY Catalytic Hydrogenation in Liquid Ammonia O-tert-BurvL-L-SERYL-S-... 

REMOVAL OF N -BENZYLOXYCARBONYL GROUPS FROM SULFUR-CONTAINING PEPTIDES BY CATALYTIC HYDROGENATION IN LIQUID AMMONIA O-tcrf-BUTYL-L-SERYL-S-tert-BUTYL-L-CYSTEINE ferr-BUTYL ESTER... 

Ring-opening reactions with 3-alkylaziridine esters 36 take a similar course. The reactions are in practically all cases regio- and stereospecific with attack at C-3. An important difference is that the aziridine ring needs to be activated by an electron-withdrawing substituent, such as a tosyl or a benzyloxycarbonyl group. In addition, for benzenethiol, indole, and DMF, catalysis with BF3 was necessary (Scheme 22) [31]. 

FIGURE 6 Molecular structures of poIy(CTTE), poly(CTTH), and poly(CTTP), a homologous series of tyrosine-derived polymers used in a study of the effect of the C-terminus protecting group on the materials properties of the resulting polymers. Cbz" stands for the benzyloxycarbonyl group (47). 

Based on these monomeric building blocks a series of four structurally related poly(iminocarbonates) were synthesized carrying either no pendant chains at all [poly(Dat-Tym) ], a N-benzyloxycarbonyl group as pendant chain [poly(Z-Tyr-Tym)], a hexyl ester group as pendant chain (poly(Dat-Tyr-Hex) ], or both types of pendant chains simultaneously (poly(CTTH)] (Fig. 7). 

Entry 13 shows cyclization with concomitant loss of the benzyloxycarbonyl group. The TS for this reaction is 5-exo with conformation determined by the pseudoequatorial position of the methyl group. 

The presence of a stiff benzyloxycarbonyl group in Z-Tyr-Tym did not significantly improve the processibility or solubility of the corresponding polyiminocarbonate Poly(Z-Tyr-Tym iminocarbonate), like poly(Dat-Tym iminocarbonate), was an insoluble, and nonprocessible material. On the other hand,... 

Two amino acid stereoisomers protected by benzyloxycarbonyl groups were deprotected in different ways. One isomer was hydrogenolyzed on 5% Pd/C (0.05 mol Pd/mol) in AcOEt-MeOH for 16 hours at ambient pressure and temperature. The other isomer was dissolved in MeOH, and cyclohexene (10 mol/mol) was added under nitrogen followed by 5% Pd/C (0.18 mol Pd/mol). The temperature was immediately raised to reflux, and stirring was continued for 7 minutes (Scheme 4.60).266... 

Dihydropyrrole a-ketoester 423 when reacted with 2,2,2-trichloroethyl carbazate in refluxing xylene underwent smooth cycloaddition to afford cycloadduct 48 in 86% yield. Reaction of 423 with thiosemicarbazide in acetic acid yielded a product mixture to give the tetracycle 48. Its benzyloxycarbonyl group was cleaved by reaction with HBr to give crystalline 424 <2002JOG7880> (Scheme 94). 

Treatment of 25 and 26, respectively, in pyridine with equimolar amounts of benzyloxycarbonyl chloride at low temperature, followed by addition of an excess of ethoxycarbonyl chloride, yielded the corresponding methyl 5-0-(benzyloxycarbonyl)-2-0-(ethoxycarbonyl)-/3-(57) and -a-D-glucofuranosidurono-6,3-lactone (58). Hydrogenolysis of the benzyloxycarbonyl group resulted in formation of methyl 2-0-(ethoxycarbonyl)-/ - (59) (70%) and -a-D-glucofuranosidurono-6,3-lactone (60) (30%), respectively, both in crystalline form. The /3-D... 

AM Felix, MH Jimenez, T Mowles, J Meienhofer. Catalytic hydrogenolysis in liquid ammonia. Cleavage of V -benzyloxycarbonyl groups from cysteine-containing peptides with terf-butyl side chain protection. Int J Pept Prot Res 11, 329, 1978. 

K Kuromizu, J Meienhofer. Removal of the JW-benzyloxycarbonyl group from cysteine-containing peptides by catalytic hydrogenolysis in liquid ammonia, exemplified by a synthesis of oxytocin. J Am Chem Soc 96, 4978, 1974. 

AE Jackson, RAW Johnstone. Rapid, selective removal of benzyloxycarbonyl groups from peptides by catalytic transfer hydrogenation. Synthesis 685, 1976. 

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