10.1021/ol701427k CCC: $37.00 Published on Web įamily showed potent cytotoxicity (IC50 values ranging from 3.7 nM to 0.99 µM) against several human tumor cell lines in vitro, GEX 1A is the only one possessing antitumor activity in vivo. Structures of GEX 1 family members (1-6). A7847, displayed selective phytotoxicity against a range of broadleaf annual weeds while remaining harmless to coplanted wheat.1 In a search for new antitumor agents, 1 was reisolated from a fermentation culture broth with five other structurally related GEX 1 members (2-6, Figure 1).2 While several members of thisįigure 1.

Herboxidiene/GEX 1A (1), a secondary metabolite originally isolated from Streptomyces sp. Panek*ĭepartment of Chemistry and Center for Chemical Methodology and Library DeVelopment, Metcalf Center for Science and Engineering, Boston UniVersity, 590 Commonwealth AVenue, Boston, Massachusetts 02215 Received June 18, 2007Ī convergent enantioselective synthesis of herboxidiene/GEX 1A (1) is described that features a double stereodifferentiating crotylation, annulation, and a silicon-based sp2−sp2 cross-coupling to assemble the conjugated diene. Total Synthesis of Herboxidiene/GEX 1A Yun Zhang and James S.

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