A stereoselective process for the preparation of novel phosphonoalkylphosphinates
作者:Frank H. Ebetino、Jeffrey D. Berk
DOI:10.1016/s0022-328x(96)06846-5
日期:1997.2
We have devised both a contiguous and a stepwise strategy for the synthesis of the pyridylaminomethane-based class of phosphonoalkylphosphinates (PAPs) that form via the intermediacy of the phosphonoethoxyaminomethane XIa. The PAPs result from condensation of picolines and phosphonoacetals in high chemoselective yield. Following reduction of aminopyridine IIIb, the unprecedented Pt(0)-catalyzed epimerization of the chelated amidine [(hydroxy)methylphosphinyl]-[(3-methyl-2 -piperidinyl-idene)amino]methylphosphonic acid (IIIa) yielded a single racemic pair of PAPs (IIIc). The epimerization was found to occur more slowly than amidine formation itself.