STEREOCHEMISTRY OF 1,2-OXAPHOSPHOLANES-I SYNTHESIS, 1H AND 13C NMR STUDIES AND EQUILIBRATION OF DIASTEREOMERIC 2-METHOXY-2-OXO-3,5,5-TRIMETHYL-1,2-OXAPHOSPHOLAN-3-OLS

Article abstract of DOI:10.1016/S0040-4020(01)88692-0

Both diastereomers 1A and 1B of the title compound were obtained for the first time, as well as the ring-opened product 6.Pure 1A and 1B were equilibrated in the presence of sodium methoxide in methanol to give 45:55 mixture of 1A and 1B.The same mixture was produced from 6 with either MeONa/MeOH or HCl/MeOH solutions.Triethylamine-catalyzed cyclisation of 6 led to a 15:85 mixture of 1A and 1B.The cis relationship of the OH and P=O groups in 1A and 7A was established by ¹H and ¹³CNMR spectra.Predominant conformations of 1A and 1B and their derivatives were deduced from ³J_HCCP and ³J_CCOP coupling constants.A possible mechanism of the transformations described in the paper is discussed.