摘要
The tricyclic compound 1, a key intermediate of the pentacyclic core of Et 743 and its analogues, was synthesized. Its 11-epimer was found as the product of racemization when BOP was used as the coupling agent, but not when BOP-C1 used in the same reaction. The stereochemistry of both isomers was confirmed on basis of the 1H NMR and NOE-difference spectra.
The tricyclic compound 1, a key intermediate of the pentacyclic core of Et 743 and its analogues, was synthesized. Its 11-epimer was found as the product of racemization when BOP was used as the coupling agent, but not when BOP-C1 used in the same reaction. The stereochemistry of both isomers was confirmed on basis of the 1H NMR and NOE-difference spectra.
