Spirastrellolide Studies. Synthesis of the C(1)-C(25) Southern Hemispheres of Spirastrellolides A and B, Exploiting Anion Relay Chemistry

Construction of the C(1)-C(25) southern fragments of both spirastrellolide A and B are described. Highlights of the syntheses include effective use of the three component anion relay chemistry (ARC) tactic recently introduced by our laboratory, a stereoselective spirocyclization via concomitant Ferrier reaction to elaborate the BC spiroketal and use of two dithiane unions to install the A ring as well as C(22)-C(25) fragment. The synthesis proceeded with longest linear sequences of 33 and 32 steps respectively for spirastrellolide A and spirastrellolide B.

The Spirastrellolides: Construction of the Southern C(1)−C(25) Fragment Exploiting Anion Relay Chemistry

Effective construction of the southern C(1)-C(25) fragment of spirastrellolide A has been achieved. Central to this venture was the use of four dithiane unions, including the highly effective deployment of the anion relay chemistry (ARC) tactic recently introduced by our laboratory.