180512-29-2Relevant academic research and scientific papers
Synthetic studies on actinobolin and bactobolin: Synthesis of N-desalanyl-N-[2-(trimethylsilyl)ethanesulfonyl] derivatives from a common intermediate and attempted removal of the SES protecting group
Ward, Dale E.,Gai, Yuanzhu,Kaller, Brian F.
, p. 5498 - 5505 (1996)
Two closely related syntheses of 5,6-O-(2-propylidene)-N-desalanyl-N-[2-(trimethylsilyl)ethanesulfonyl] bactobolin (9b) from (+)-12, an intermediate previously prepared from D-glucose, are reported. In each case, the key step involves a precedented stereoselective addition of LiCHCl2 in the presence of CeCl3 te a suitably protected α-amino ketone. Intermediates from both synthetic routes te 9b can be prepared by degradation of actinobolin (2) thereby establishing a potential method for the transformation of actinobelin into bactebolin. An efficient route to 5,6-O-(2-propylidene)-N-desalanyl-N-[2-(trimethylsilyl)ethanesulfonyl] actinobolin (7b) from (+)-12 involving an unexpected cyclization of 29 was discovered. The 2-(trimethylsilyl)ethanesulfonyl (SES) protecting group in 7b was removed by reaction with Bu4NF in wet THF. The nature of the Bu4NF reagent was found te be important to the outcome of the reaction. Several improvements over our previously reported synthesis of actinobolin from D-glucose are noted. Although precedented, the removal of the SES protecting group from 9b could not be achieved thereby preventing completion of a total synthesis of bactobolin.
