THE REGIOSELECTIVITY OF NITRONE CYCLOADDITIONS TO VINYL PHOSPHORUS-COMPOUNDS

The 13-dipolar cycloadditions of nitrones 1-5 to diphenylvinylphosphine oxide (6) sulfide (7) and selenide (8) were carried out. The cycloadditions of the nitrone 3 as a model to substituted vinylphosphorus derivatives 28-36 were also carried out with satisfactory results with the exception of the sulfoxide 33. Nuclear Magnetic Resonance spectroscopy (31p 1H and 13C) allowed the complete unambiguous identification and assignment of the regiochemistry to all the products as well as their relative quantitative determination. The relative stereochemistry of isoxazolidine stereocenters was also assigned to compounds 9-23 and 37-46 on the basis of 1H and 13C NMR data. © 1990.