Structure and carbon-13 nuclear magnetic resonance assignments of versiconal acetate, versiconol acetate, and versiconol, metabolites from cultures of Aspergillus parasiticus treated with dichlorvos

Abstract

The structure of versiconal acetate, a metabolite elaborated by cultures of Aspergillus parasiticus treated with dichlorvos was investigated. ¹H and ¹³C n.m.r. studies of versiconal acetate and its 3,6-OO-dimethyl derivative indicated that versiconal acetate exists in polar solvents such as (CD₃)₂SO as an equilibrium mixture of the isomers (6a–c). In (CD₃)₂CO solution the angular hemiacetal form (6c) was absent. Similarly, 3,6-OO-dimethyl-versiconal acetate exists in (CD₃)₂SO solution as the angular hemiacetal (7b) whereas in CDCl₃ solution the compound is present as the branched benzylic aldehyde (7a). Two minor metabolites were identified as versiconol acetate (11) and versiconol (12).