Tomohiro Nagasawa

Enantioselective total synthesis of aspergillide C.

The first enantioselective total synthesis of aspergillide C, a cytotoxic 14-membered macrolide isolated from the marine-derived fungus Aspergillus ostianus, has been accomplished from a commercially available chiral glycidol derivative by a 12-step sequence involving an expeditious preparation of a cyclic acetal intermediate and a trans-selective Ferrier-type two-carbon homologation reaction.

Enantioselective Synthesis of Aspergillide B

The enantioselective synthesis of aspergillide B, a 14-membered macrocyclic cytotoxin, was achieved in a 49% yield via 7 steps from a synthetic intermediate of aspergillide C. The spectroscopic data and specific rotation value for the synthetic material matched those of natural aspergillide B.

Stereoselective Approach to the Racemic Oxatetracyclic Core of Platensimycin

A highly stereoselective synthesis of the racemic oxatetracyclic core of platensimycin has been accomplished from a known bicyclic epoxy lactone by an 11-step sequence that involves a Diels-Alder cyclcoaddition to construct its cis-decalenone structural motif with complete regio- and stereoselectivity and a ring-closing metathesis to establish its whole carbon framework.

Formal total synthesis of lactimidomycin.

A concise synthesis of an intermediate of lactimidomycin, a glutarimide-containing macrocyclic polyketide produced by an actinomycete, has been accomplished in 35% overall yield from a known vinylketene silyl N,O-acetal by a 10-step sequence that involves two types of asymmetric aldol reactions to install all the stereocenters, the Stille coupling to set up the whole carbon famework, and the Yamaguchi lactonization to construct the 12-membered macrolactone ring.