Synthesis of 1‐Aryl‐1,2,3,4,5,6‐hexahydrophosphinine 1‐Oxides

Abstract

Possibilities for the synthesis of 1‐(2,4,6‐triisopropylphenyl‐)1,2,3,4,5,6‐hexahydrophosphinine oxide (2) have been explored. The trivial method based on the hydrogenation of the corresponding dihydrophosphinine oxides (8a–e) was suitable only for the preparation of hexahydrophosphinine oxides containing a trimethylphenyl or methylphenyl group on the phosphorus atom (9a–c). The triisopropylphenyl product (2) was synthesized by the stepwise reduction of the double bonds of starting material 1. Hence, the ring contraction side reaction, observed during the catalytic hydrogenation, could be eliminated. The unusual reactivity was studied by quantum chemical calculations.

Keywords:

• Dihydrophosphinine oxides
• Reduction
• Ring contraction hexahydrophosphinine oxides
• Theoretical calculations

Acknowledgments

The authors are grateful for the OTKA support of the work (Grant No. T 042479). The advice of Professor Emeritus Dr Harry R. Hudson (London Metropolitan University) is appreciated.