HIGHLY STEREOSELECTIVE ACCESS TO NOVEL 2,2,4-TRISUBSTITUTED TETRAHYDROFURANS BY HALOCYCLIZATION: PRACTICAL CHEMOENZYMATIC SYNTHESIS OF SCH 51048, A BROAD-SPECTRUM ORALLY ACTIVE ANTIFUNGAL AGENT

Article abstract of DOI:10.1016/0040-4039(95)00143-Z

A convenient synthesis of (-)-(2R)-cis-tosylate 2 is reported via stereoselective 5-exo iodocyclization of the optically active 2,2-disubstituted olefin 9a.Enzymatic desymmetrization of the homoallylic diol 4 with Novo SP435 allowed optimal pro-(S) selectivity to provide the desired (-)-(S)-monoacetate 9a.Under the irreversible reaction conditions, the presence of a bulky aryl substituent on the 2,2-disubstituted olefin seems to determine stereochemical outcome of these halocyclizations.