NMR study of 2-alkoxy-1,3,2-dioxaphospholanes. II—molecular conformation of alkoxy substituents

✍ Scribed by D. Besserre; S. Coffi-Nketsia

• Publisher: John Wiley and Sons
• Year: 1980
• Tongue: English
• Weight: 583 KB
• Volume: 13
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1270130502

✦ Synopsis

Abstract

The conformation of some 2‐σ‐1,3,2‐dioxaphospholanes (σ=OAlkyl, CI) is studied. The determination of the ^2^J(POC) and ^3^J(POCC) coupling constants, which are influenced by the bulk of the alkoxy group, is a means of obtaining information about the rotation around the POR bond, which is dependent on steric interactions between the phosphorus lone pair, the alkoxy group and the substituents on the ring. When σ is a tert‐butoxy group, a direct ‘through‐space’ interaction is found between the phosphorus atom and one of the primary carbons of the OR group. If there is no substituent on the ring, the ^31^P chemical shifts are little affected by changes in OR; a diamagnetic effect is observed, however, in the case of the tert‐butoxy group which is enhanced for the 4,4,5,5‐tetramethyl derivatives.