Bicyclic phosphanes: synthesis, stereochemistry, and conformation

Abstract

From the new family of 2,8-dioxa-5-aza-1-phospha^IIIbicyclo[3.3.0]octanes (bicyclic phosphanes)(1)–(5), three derivatives (3)–(5) were studied by synthesis, oligomerization, and n.m.r. spectroscopy. Conformational analysis shows that the five-membered rings take on an envelope conformation. The orientation of the folds is known for the majority of the compounds. Comparison of stereochemical data between phosphanes (2)–(4) and the corresponding 1-phenyl-2,8-dioxa-5-aza-1-phospha^Vbicyclo[3.3.0]octanes (bicyclic phosphoranes)(7a)–(9a) underlines the conformational consequences due to the change of hybridization of the nitrogen and phosphorus atoms.