Coupling constants 1J(15N,31P) as a probe for the conformational equilibria of 2-amino-substituted 1,3,2λ5-oxazaphosphinan-2-ones†
Abstract
The 15N NMR spectra of both P(2) diastereomers of the trans-fused 2-bis(2-chloroethyl)amino-3,4,4a,5,6,7,8,8a-octahydro-1,3,2λ5-benzoxazaphosphinin-2-ones and their 3-methyl and 3-benzyl derivatives have been measured. Depending on the P(2) configuration, the coupling constants 1J(15N,31P) vary markedly. The applicability of the coupling between exocyclic nitrogen and phosphorus for determination of the heteroring conformation is discussed.