Boc-L-cysteine

The CM of fatty acids and derived compounds also has been used for the production of fine chemicals that are difficult to obtain by other synthetic approaches. Some examples include the synthesis of a plant growth stimulant, an insect pheromone precursor, the sex pheromone of the peach twig borer moth, and others [28]. Furthermore, the conjugation of fatty acid derivatives, sugars, and amino acids via CM was shown by Vemall and Abell [41]. C4 with a catalyst loading of 20 mol% was used to perform the CM of either Ai-Boc-L-ly sine or N-Boc-L-cysteine bearing a 10-undecenoic chain with methyl 10-undecenoate or a sugar olefin. 

Using chiral thiols for derivative formation, isoindoles are formed from amino acids and amino alcohols. BOC-L-cysteine, N-acetyl-L-cysteine, Af-acetyl-D-penicillamine [340] and l-thio-jS-D-glucose [341] have been shown to be suitable reagents which allow the separation of most amino acid enantiomers using reversed phase column chromatography. Thus, OPA/N-acetyl-L-cysteine has been used among others for the separation of enantiomers of aspartate [342], baclofen [343], norepinephrine, dopa [344] and lombricine [345]. 

OPA in combination with chiral thiols is one method used to determine amino acid enantiomers. A highly fluorescent diastereomeric isoindole is formed and can be separated on a reverse-phase column. Some of these chiral thiols include N-acetyl-L-cysteine (NAC), N-tert-butyloxy-carbonyl- L-cysteine (Boc-L-Cys), N-isobutyryl- L-cysteine (IBLC), and N-isobutyryl- D -cysteine (IBDC). Replacing OPA-IBLC with OPA-IBDC causes a reversal in the elution order of the derivatives of D- and L-amino acids on an ODS column (Hamase et al., 2002). Nimura and colleagues (2003) developed a novel, optically active thiol compound, N-(tert-butylthiocarbamoyl)- L-cysteine ethyl ester (BTCC). This reagent was applied to the measurement of D-Asp with a detection limit of approximately 1 pmol, even in the presence of large quantities of L-ASP. 

A further approach for the synthesis of nonsymmetrically protected lanthionines is the conversion of thiosulfinates of symmetrically protected cystine derivatives into nonsymmetrically protected cystines via a reaction with a cysteine derivative and subsequently the conversion of the resulting unsymmetrically protected cystine into the nonsymmetrically protected lanthionines with a tris(dialkylamino)phosphineJ26l The oxidation of the symmetrically protected cystine, e.g. A,AT-bis(benzyloxycarbonyl)-L-cystine diethyl ester, of one stereochemical configuration to the thiosulfinate with m-chloroperoxybenzoic acid is essentially quantitative. The nonsymmetrical cystine is then formed in a subsequent step by the addition of the /V-/er/-butoxycarbonyl-L-cysteine tert-butyl ester derivative to give N-Z-N -Boc-L-cystine ethyl ferf-butyl diester. The desired 2f ,6f -lanthionine is then formed in the presence of P(NEt2)3 in yields of >50%. 

Cl 5H1608 7-(beta-D-glucopyranosyloxy)-2H-1-benzopyran 93-39-0 25.00 1.3267 2 28630 C15H21N04S boc-S-benzyl-L-cysteine 5068-28-0 25.00 1.1782 2... 

The cysteine 5-(tert-butyl) derivative is obtained by reaction of cysteine with isobutenef ° l or teri-butyl acetatef under acid catalysis. Under both of these reaction conditions, the carboxy group is esterified and has to be deprotected by TFA treatment. A more general procedure, applicable for the synthesis of both 5-(tert-butyl) (tBu) and 5-(l-adamantyl) (1-Ada) derivatives (Scheme 10), is based on S-alkylation of cysteine with the teri-alcohols under acidic conditions.The related A -Boc and A -Fmoc derivatives are obtained by standard procedures. 

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