PHOSPHONIC SYSTEMS .12. FRAGMENTATION-REARRANGEMENT OF DIALKYL 2-ACYLOXYALKYLPHOSPHONATES

Dialkyl esters of 2-acyloxyalkylphosphonic acids, RCH(OAc)CH2PO3R2', u ndergo thermolytic fragmentation to an alkene RCH=CH2, a new ester AcO R', and an alkyl metaphosphate R'OPO2. The reaction represents a new t ype of a process in which a metaphosphate species is generated from a neutral precursor and involves alkyl group (R') migration as a prerequ isite for the reaction. Mechanistic studies indicate that the reaction involves interaction between the phosphoryl group and the electrophil ic center of the Ac group, followed by the intramolecular dealkylation of the P-O-R' function and the subsequent fragmentation of the interm ediate.