Synthesis of (3S)-(+)-diethyl-2-(l-oxoethyl)-5-phenyl-(3 N-p-Toluenesulfinamido) pentylphosphonate
It has been found that reactions between pentacovalent oxaphospholenes (P(V)) and various electrophiles produced substituted phosphonates under mild conditions. Using an imine as an electophile with the oxaphospholene would produce a y-phosphono amino acid. However, simple imines are not good enough electrophiles to react with a standard P(V) compound. Imines with attached electron withdrawing sulfoxide groups proved to be better electrophiles. The imine was prepared by the reaction of hydrocinnamaldehyde with p-toluenesulfmamide to produce (S)-(+)-N-(3-phenyl)- propyl-p-toluenesulfmamide which was then treated with 2,2,2-triethoxy-2,2-dihydro-5- methyl-l,2X5-oxaphospholene (P(V)) with MgBr2 as a Lewis acid to produce the desired product, (3S)-(+)-diethyl-2-(1-oxoethyl)-5-phenyl-(3-N-p-toluenesulfinamido) pentylphosphonate.