Synthetic Study of Curacin A, A Novel Antimitotic Agent Isolated from Cyanobacterium Lyngbya majuscula.

Curacin A is a novel antitumor antimitotic agent isolated from a Caribbean cyanobacterium Lyngbya majuscula. Synthesis of the four stereoisomers of (+) -and (-) -2- (2-methyl) cyclopropyl-4- (1-propenyl) thiazoline was achieved to elucidate the absolute configuration of three chiral centers of natural curacin A. Next, the asymmetric total synthesis of curacin A was achieved in high stereoselective manner. 2-Methylcyclopropyl moiety was synthesized by asymmetric double Simmons-Smith cyclopropanation Thiazoline moiety was constructed from L-cycsteine and side chain was synthesized from geraniol. A series of side chain analogs of curacin A were also synthesized to find the minimal and common active structure to colchicine. However, these analogs showed weak or no antitubulin activity suggesting that the side chain of curacin A was restrictly recognized by microtubule proteins.