Synthesis, Properties and Stereochemistry of 2-Halo-1,2λ⁵-oxaphosphetanes

Abstract

Abstract:Results of research into four-membered 2-halo-1,2λ 5 -oxaphosphetane phosphorus(V)-heterocycles are presented. The preparation of 2-halo-1,2λ 5 -oxaphosphetanes by reaction of Phaloylides with carbonyl compounds is described. The mechanism of asynchronous [2+2]-сycloaddition of ylides to aldehydes was proposed on the base of low-temperature NMR investigations. 2-Halo-1,2λ 5 -oxaphosphetanes were isolated as individual compounds and their structures were confirmed by 1 Н-, 13 C-, 19 F-and 31 Р-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-halon-1,2λ 5 -oxaphosphetanes are reviewed. The 2-chloro-1,2λ 5 -oxaphosphetanes, rearrange with formation of 2-chloroalkylphosphonates or convert into trans-phosphorylated alkenes depending on the substituents at the α-carbon atom. Prospective synthetic applications of 2-halo-1,2λ 5 -oxaphosphetanes are analyzed. The 2-halo-1,2λ 5 -oxaphosphetanes may be easily converted to various alkenylphosphonates: allyl-or vinylphosphonates, phosphorus ketenes, thioketenes, ketenimines.