approach to trichloroacetimidate 8c commenced with the iodonium ion mediated glycosidation of ethyl 2,3,4-tri-O-benzoyl-1-thio-α-L-rhamnopyranside (15) with 1,2:5,6-diisopropylidene-D-glucofuranose (16) to afford disaccharide 17, which was transformed into 8c in five steps. Condensation of 8a–c with 2-[3,4-di-(tert-butyldimethyl-silyloxy)phenyl]ethanol (12) gave, after deacylation, key intermediate
NHC catalyzed enantioselective Coates-Claisen rearrangement: a rapid access to the dihydropyran core for oleuropein based secoiridoids
作者:Seenuvasan Vedachalam、Nithya Murugesh、Priyanka Chakraborty、Ramasamy Karvembu、Xue-Wei Liu
DOI:10.1039/c7nj04057a
日期:——
functionalized enantioselective dihydropyran core of secoiridoids using an N-heterocyclic carbene (NHC) catalyzed Coates-Claisen rearrangement mechanism. The key steps of the synthesis are (i) the highly enantioselective NHC catalyzed Coates-Claisen rearrangement for the dihydropyran core, (ii) the assembly of the target dihydropyran core structure of oleuropein from a highly diastereoselective exocyclic trans