Reactionof 2-R-4-Oxo-5,6-benzo-1,3,2-dioxaphosphorinanes with Methyl 2-Oxo-3,3,3-trifluoropropionate. Steric Structure of 5-Oxo-4-methoxycarbonyl-4-trifluoromethyl-2-ethoxy-6,7-benzo-1,4,2-dioxaphosphepine 2-Oxide

摘要

Reaction of 2-R-4-oxo-5,6-benzo-1,3,2-dioxaphosphorinanes with methyl 2-oxo-3,3,3-trifluoro-propionate, depending on the order of mixing the reactants and on temperature, yields either the products or ring extension, 5-oxo-4-methoxycarbonyl-4-trifluoromthyl-2-ethoxy-6,7,-benzo-1,4,2-dioxaphosphepine 2-oxides, with a high regioselectivity, or pentaalkoxyspirophosphoranes with a moderate stereoselectivity. The structure of the products was determined by ~1H, ~13C, ~19F, and ~31P NMR spectroscopy. The steric structure of the isolated diastereomer of 5-oxo-4-methoxycarbonyl-4-fluoromethyl-2-ethoxy-6,7-benzo-1,4,2-dioxaphosphepine 2-oxide was studied by single crystal X-ray diffraction.