Synthesis, properties and stereochemistry of 2-halo-1,2γ5-oxaphosphetanes

Abstract

Results of research into four-membered 2-halo-1,2γ5-oxaphosphetane phosphorus(V)-heterocycles are presented. The preparation of 2-halo-1,2γ5-oxaphosphetanes by reaction of P-haloylides with carbonyl compounds is described. The mechanism of asynchronous [2+2]-cycloaddition of ylides to aldehydes was proposed on the base of low-Temperature NMR investigations. 2-Halo-1,2γ5-oxaphosphetanes were isolated as individual compounds and their structures were confirmed by 1H-, 13C-, 19F-and 31P-NMR spectra. These compounds are convenient reagents for preparing of various organic and organophosphorus compounds hardly available by other methods. Chemical and physical properties of the 2-halo-1,2γ5-oxaphosphetanes are reviewed. The 2-chloro-1,2γ5-oxaphosphetanes, rearrange with formation of 2-chloroalkyl-phosphonates or convert into transphosphorylated alkenes depending on the substituents at the α-carbon atom. Prospective synthetic applications of 2-halo-1,2γ5-oxaphosphetanes are analyzed. The 2-halo-1,2γ5-oxaphosphetanes may be easily converted to various alkenylphosphonates: Allyl-or vinylphosphonates, phosphorus ketenes, thioketenes, ketenimines.