Synthesis and Spatial Structure of 2,5-Dioxo-4-Dialkoxy-Phosphoryl-4-Aryl-6,7-Benzo-1,3,2-Dioxaphosphepines

Phosphorus (111) containing dcrivatives of salicylic acid easily react with carbonyl compounds with formation of cycloexpansion products - 1,3,2- or 1,4,2-dioxaphosphepines. For the first time we have shown that dialkyl-l-oxólkylphosphonates react with 2-R-4-oxo-5,5-benzo-1,3,2-dioxaphosphorinanes and yield 1,3,2-dioxaphosphepines (I) with high stereoselectivity. The configuration of the preferable diastereoisomer (IId) has been determined by X-ray analysis. The hydrolysis of compounds (IIa-c) leads to formation of 2-hydroxy-2-oxo-1,3,2-dioxaphosphepines (III). The structure of phosphepine (IIIb) in crystal is shown on the figure. The work is supported by the Leading Scientific School Foundation of Russia (grant N 96-15-97330) and the Russian Foundation for Basic Research (grant N 98-03-33266).