Stereoselective Synthesis of Cyclic P(V) Compounds via Stereoconvergent Nucleophilic Substitution

We report a simple, scalable, and stereoselective synthesis of chiral oxazaphosphoramides using phosphoryl chloride, an L-serine derivative, and various primary and secondary amines. Excellent stereoselectivities (typically >99:1 dr) were achieved via an unexpected, stereoconvergent nucleophilic substitution process, wherein two diastereomers of an oxazaphosphorochloridate intermediate were converted to a single diastereomer of an oxazaphosphoramide via distinct pathways. Electrochemical decarboxylative transformations allowed the products to be further diversified to afford three types of chiral oxazaphosphoramides with different ring substitutions.