1235303-60-2Relevant academic research and scientific papers
A flexible approach to azasugars: asymmetric total syntheses of (+)-castanospermine, (+)-7-deoxy-6-epi-castanospermine, and (+)-1-epi- castanospermine
Liu, Gang,Wu, Tian-Jun,Ruan, Yuan-Ping,Huang, Pei-Qiang
experimental part, p. 5755 - 5768 (2010/08/19)
The asymmetric total synthesis of natural azasugars (+)-castanospermine, (+)-7-deoxy-6-epI-castanospermine, and synthetic (+)-1-epi-castanospermine has been accomplished in nine to ten steps from a common chiral building block (S)-8. The method features a powerful chiral relay strategy consisting of a highly diastereoselective vinylogous Mukaiyama-type reaction with either chiral or achiral aldehydes (≥ 95% de; de = diastereomeric excess) and a diastereodivergent reduction of tetramic acids, which allows formation of three continuous stereogenic centers with high diastereo-selectivities. The method also provides a flexible access to structural arrays of 5-(α-hydroxyalkyl) tetramic acids, such as 17/34, and 5-(α-hydroxyalkyl)-4-hydroxyl-2- pyrrolidinones, such as 18 and 25/35 a. The method constitutes the first realization of the challenging chiral synthons A and D and thus of the conceptually attractive retrosynthetic analysis shown in Scheme 1 in a highly enantioselective manner.
