Application of a tandem seleno-michaelialdol reaction in the total syntheses of (+)-Pericosine B, (+)-Pericosine C, (+)-COTC and 7-chloro-analogue of (+)-Gabosine C

Synthesis of (+)-Pericosine B, (+)-Pericosine C, (+)-COTC and a 7-chloro-analogue of (+)-Gabosine C was achieved via tandem seleno-Michael/aldol reactions as key steps. The carbasugar linear precursor was obtained from cheap and readily available D-ribose in 7 steps which included resolution of the p-ribopyranose and the D-ribofuranose forms. Further transformation of the cyclic product involving a regio-selective Steglich esterification or methylation of the secondary hydroxyl group gave rise to protected (+)-COTC, (+)-Pericosine B and (+)-Pericosine C. Deprotection of benzyl ethers at -78 degrees C gave the titled compounds in satisfactory yields. (C) 2020 Elsevier Ltd. All rights reserved.