A versatile and concise strategy has been developed (Scheme 1) for the enantioselective synthesis of semperoside A 1 which is endowed with an unusually glucosylated iridane structure. The crucial step was a Hg(II)-mediated electrophilic heteroatom cyclization of beta-glucoside 4 that readily led to the iridane skeleton while installing the C-2 and C-3 stereocenters with complete stereocontrol. This expeditious route is unprecedented among synthetic approaches to iridoid glycosides and smoothly overcomes the hemiacetals glucosidation issue. The present inaugural total synthesis of semperoside A was achieved in 10 steps and 17% overall yield from the enantiomerically pure lactone 8, thus proving the absolute stereochemistry of 1 unequivocally.
Enantioselective Total Synthesis of Semperoside A
VIDARI, GIOVANNI;ZANONI, GIUSEPPE
2004-01-01
Abstract
A versatile and concise strategy has been developed (Scheme 1) for the enantioselective synthesis of semperoside A 1 which is endowed with an unusually glucosylated iridane structure. The crucial step was a Hg(II)-mediated electrophilic heteroatom cyclization of beta-glucoside 4 that readily led to the iridane skeleton while installing the C-2 and C-3 stereocenters with complete stereocontrol. This expeditious route is unprecedented among synthetic approaches to iridoid glycosides and smoothly overcomes the hemiacetals glucosidation issue. The present inaugural total synthesis of semperoside A was achieved in 10 steps and 17% overall yield from the enantiomerically pure lactone 8, thus proving the absolute stereochemistry of 1 unequivocally.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
