Organophosphorus Chemistry 34 1 . The Reaction of Alkyl Phosphites and Hexamethylphosphorus Triamide with 1-Phenyl-3-methyl-4-ylidene-5-pyrazolones

Abstract

1-Phenyl-3-methyl-4-ylidene-5-pyrazolones ( 1a-c ) produce the respective 1:1 phosphonate adducts ( 4a-i ) upon reaction with the appropriate dialkyl phosphites ( 2a-c ). The reaction of 1a-c with trialkyl phosphites ( 3a-c ) proceeds only in presence of water, also to give phosphonates 4a-c almost exclusively. Hexamethylphosphorus triamide ( 3d ) was successfully utilized to introduce the bis(dimethylamino)-phosphoryl function in the f , g -unsaturated carbonyl moiety in 1a-c , producing phosphoramidates 15a-c . Possible reaction mechanisms were discussed. Compatible elemental and spectroscopic results were recorded for the new products.

Keywords:

• Alkyl Phosphites
• Hexamethylphosphorus Triamide
• Phosphonates
• Phosphoromidates
• Reaction Mechanism
• Ylidene Pyrazolones