Asymmetric dihydroxylation and regioselective C-3 indole coupling routes to the anticoccidial antibiotic (+)-diolmycin A2
摘要:
A highly enantioselective synthesis of (+)-diolmycin A2 starting from 4-hydroxybenzaldehyde and employing the Sharpless asymmetric dihydroxylation and CH3NO2 solvent assisted regioselective C-3 coupling of indole as the key steps is described. (C) 2002 Elsevier Science Ltd. All rights reserved.
Investigating the Initial Steps in the Biosynthesis of Cyanobacterial Sunscreen Scytonemin
作者:Emily P. Balskus、Christopher T. Walsh
DOI:10.1021/ja807192u
日期:2008.11.19
(1) functions as a sunscreen, absorbing harmful UV-A radiation. Using information from a recently identified gene cluster, we propose a biosynthetic route to this pigment. We also report the characterization of two enzymes, NpR1275 and NpR1276, which are involved in the initial stages of this pathway. A regioselective acyloin reaction between indole-3-pyruvic acid (4) and p-hydroxyphenylpyruvic acid
Epoxide opening reactions with indole are efficiently accelerated under highpressure conditions in the presence of a catalytic amount of ytterbium(III) trifluoromethanesulfonate to afford tryptophol derivatives. The procedure is successfully applied for an enantioselectivesynthesis of (+)-diolmycinA2.