Synthesis of (4 R ,5 S )‐Melithiazols F and I

Palladium‐catalyzed cyclization‐methoxycarbonylation of (2 R ,3 S )‐3‐methylpenta‐4‐yne‐1,2‐diol ( 8 ) derived from the (2 R ,3 S )‐epoxybutanoate 7 followed by methylation gave the tetrahydro‐2‐furylidene acetate (–)‐ 9 , which was converted into the left‐half aldehyde (+)‐ 4 . A Wittig reaction between (+)‐ 4 and the phosphoranylide derived from the bithiazole‐type phosphonium iodide 5 using lithium bis(trimethylsilyl)amide afforded (+)‐(4 R ,5 S )‐melithiazol F ( 1 ), whose spectroscopic data were identical with those of the natural product 1 . Moreover, the synthesis of (+)‐(4 R ,5 S )‐melithiazol I ( 2 ), was achieved by the same synthetic strategy as that of (+)‐(4 R ,5 S )‐melithiazol F ( 1 ). The antifungal activity of the synthetic melithiazols F ( 1 ) and I ( 2 ) against the phytopathogenic fungus, Phytophthora capsici , was evaluated by using a paper disc assay method.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)