An Efficient Synthesis of <i>N</i>-Methyl Amino Acids by Way of Intermediate 5-Oxazolidinones
作者:Luigi Aurelio、John S. Box、Robert T. C. Brownlee、Andrew B. Hughes、Marianne M. Sleebs
DOI:10.1021/jo026722l
日期:2003.4.1
N-Methyl amino acids occur in many natural products. Experimental strategies are presented for a unified approach to the synthesis of N-methyl derivatives through 5-oxazolidinones of the 20 common L-amino acids. The amino acids with reactive side chains that required protecting groups or devoted syntheses for side chain construction for N-methylation to proceed included serine, threonine, tyrosine, cysteine, methionine, tryptophan, asparagine, histidine, and arginine. The studies have provided improved methods for the preparation of N-methyl serine, threonine, and tyrosine. All 20 of the common L-amino acids are now available in suitable forms for solid or solution-phase peptide synthesis.
Selective Cleavage of Cbz-Protected Amines
作者:Bruce H. Lipshutz、Steven S. Pfeiffer、Anthony B. Reed
DOI:10.1021/ol016693l
日期:2001.12.1
[GRAPHICS]Under conditions of catalytic Ni(O) and in most cases just over 1 equiv of Me2NH-BH3/K2CO3 or CS2CO3, a Cbz-protected nitrogen, which is part of a heteroaromatic ring, can be chemospecifically cleaved without affecting a Cbz group on an originally basic amine.