Mechanism

An intramolecular nucleophilic addition of phosphorus yield to carbonyl group of amide can give four membered ring oxaphosphetatne that can decompose to give the target heterocycle (Scheme 4).

Scheme 4

Examples:

K. Miyashita, K. Kondoh, K. Tsuchiya, H. Miyabe, T. Imanishi, J. Chem. Soc. Perkin Trans 1, 1996 , 1261.

B. Danieli, G. Lesma, G. Palmisano, D. Passarella, A. Silvani, Tetrahedron 1994 , 50 , 6941.

M. Le Corre, Y. Le Stane, A. Hercouet, H. Le Brown, Tetrahedron 1985 , 41 , 5313.

5.4.3 Michaelis-Arbuzov Reaction

Several modifications of the Wittig reaction have been made to improve the reactivity of the ylides. The reaction of alkyl halides with triethylphosphite gives phosphonate esters (Scheme 7). This reaction is called Michaelis-Arbuzov reaction. The phophonate esters are the precursor for the synthesis of more reactive ylides.

Scheme 5