Reactions of lithiated P-diphenyl(alkyl)(N-methoxycarbonyl)-phosphazenes with Michael acceptors and aldehydes.Synthesis of 1H-1,2-azaphosphinin-6-ones,#beta#-hydroxy(N-methoxycarbonyl)-phosphazenes and 5,6-dihydro-1,3,4-oxazaphosphinin-2-ones.

摘要

Lithium (N-methoxycarbonyl)phosphazenes add C-regioselectively to DMAD,dimethyl malonate,fumarate,and butylidenmalonate in a [1,4]manner.Only onediastereoisomer is observed with the olefinic electrophiles.With DMAD the initial adduct evolves through cyclocondensation iwht the CO_2Me group of the phosphazene and 1H-1,2-azaphosphinin-6-ones are obtained.Exceptionally,methyl phenylpropiolate reacted exclusively through the carbonyl yielding a mixture of C- and N-acylated compounds.The addition to aldehydes at -80degC affords #beta#-hydroxyphosphazenes diastereoselectively.For lithium #alpha#,#alpha#-dimethyl(N-methoxycarbonyl)phosphaxenes,the intermediate alkoxides cyclocondense at room temperature to 5,6-dihydro-1,3,4-oxazaphosphinin-2-ones.