α-Pyrazolyl-Alkylphosphonates. Part. II1: A simple and Efficient Synthesis of Diethyl 1-(pyrazol-4-yl)-alkylphosphonates

Various diethyl β-functional γ-oxo alkylphosphonates (3) were conveniently prepared using two complementary inexpensive strategies, and were reacted with hydrazine, methylhydrazine or phenylhydrazine giving regioselectively new diethyl 1-(pyrazol-4-yl)-alkylphosphonates (4), isolated in high yields.