A Convenient Synthesis of N-Fluorenylmethoxycarbonyl-N-Methyl-l-
Cysteine Derivatives [Fmoc,Me-Cys(R)-OH]

Abstract

The synthesis of N-fluorenylmethoxycarbonyl-N,S-dimethyl-l-Cysteine (1) [Fmoc,Me-Cys(Me)-OH] and N-fluor­enylmethoxycarbonyl-N-methyl-S-acetamidomethyl-l-Cysteine (2) [Fmoc,Me-Cys(Acm)-OH] is reported. The synthesis is characterized by a convenient two-step procedure from (R)-thiazolidine-4-carboxylic acid (3) via reduction and subsequent protection. Crystals of 1, which have been analyzed by single-crystal X-ray crystallography, are obtained after a simple crystallization at the end of the process, without purification of intermediates.

Key words

amino acids - peptides - cysteine - protecting groups

References

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9

It was reported that the sodium in liquid ammonia reduction of l-thiazolidine-4-carboxylic acid gave dimeric product. [4] [10] By keeping a low concentration of the acid [4] or adding one molecular portion of water, [10] dimerization was avoided. However, from our three parallel experiments following (1) low concentration procedure, (2) water addition treatment, and (3) addition of one molecular portion of water and keeping the low concentration of the acid, the best result was obtained from the low concentration procedure.