RESUMEN
The biosynthesis of corvol ethers A and B, two sesquiterpenes from Kitasatospora setae, proceeds with involvement of either one 1,3- or two sequential 1,2-hydride shifts. Quantum chemical calculations revealed that the sequence of two 1,2-hydride shifts is energetically favoured. Labelling experiments were in agreement with this finding. In addition, the stereochemical course of a reprotonation step was investigated by incubation of (13)C-labelled isotopomers of farnesyl diphosphate in water and in deuterium oxide.
Asunto(s)
Éteres/síntesis química , Modelos Teóricos , Sesquiterpenos/síntesis química , Ciclohexanoles/química , Éteres/química , Eucaliptol , Espectroscopía de Resonancia Magnética , Estructura Molecular , Monoterpenos/química , Salvia , Sesquiterpenos/químicaRESUMEN
An uncharacterized terpene cyclase from Streptomyces pratensis was identified as (+)-(1(10)E,4E,6S,7R)-germacradien-6-ol synthase. The enzyme product exists as two interconvertible conformers, resulting in complex NMR spectra. For the complete assignment of NMR data, all fifteen ((13)C1)FPP isotopomers (FPP=farnesyl diphosphate) and ((13)C15)FPP were synthesized and enzymatically converted. The products were analyzed using various NMR techniques, including (13)C, (13)Câ COSY experiments. The ((13)C)FPP isotopomers were also used to investigate the thermal rearrangement and EI fragmentation of the enzyme product.