Sulfur- and Selenium- Promoted Cyclization of Allenic Phosphonates and Phosphinates to Substituted 1,2-Oxaphosphol-3-enes; Stereochemical Consequences at Phosphorus. The Crystal and Molecular Structure of (Z)-3,5-Di-tert-butyl-2-methoxy-4-(phenylseleno)-1,2-oxaphosphol-3-ene 2-Oxide

Article abstract of DOI:10.1021/jo00157a007

A series of allenic phosphonate esters (4a-d) and phosphinate 6 were reacted with benzeneselenyl chloride.Except for 4a, which gave a simple 1,2-adduct, each ester afforded the corresponding 4-(phenylseleno)-1,2-oxaphosphol-3-ene (11b-e).Similar reaction of the esters with 2,4-dinitrobenzenesulfenyl chloride gave the corresponding 4-thio derivatives (13) in cases 4c, 4d and 6; 4a and 4b were unreactive.The diastereomers of 11b were seperated, and the structure of the Z isomer was established by X-ray crystallography.The stereochemistry of the cyclization and related reactions is discussed.