Stereoselective Synthesis of Chiral 4-(1-Chloroalkyl)-β-Lactams Starting from Amino Acids and Their Transformation into Functionalized Chiral Azetidines and Pyrrolidines

Chiral short-chain α-chloroaldehydes were prepared starting from enantiomerically pure amino acids in a three-step approach, thus providing a practical synthetic alternative for known organocatalytic α-chlorination procedures. The latter aldehydes proved to be useful starting materials for the stereoselective Staudinger synthesis of (3S,4S)-4-[(1S)-1-chloroalkyl]azetidin-2-ones in high diastereomeric ratios and good overall yields, which were used as chiral building blocks for the preparation of a number of azetidines and pyrrolidines.

以对映体纯的氨基酸为起始原料，通过三步法制备得到手性短链α-氯代醛，为现有已知的有机催化α-氯化反应提供了一种实用的合成替代方案。经证实，该类醛类可作为实用起始原料，用于立体选择性施陶丁格合成制备(3S,4S)-4-[(1S)-1-氯烷基]氮杂环丁-2-酮，所得产物具备较高的非对映异构比与良好的总收率，且可作为手性砌块用于制备多种氮杂环丁烷与吡咯烷类化合物。