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8428757 
Journal Article 
Acylphosphonates: P-C Bond Cleavage of Dialkyl Acylphosphonates by Means of Amines. Substituent and Solvent Effects for Acylation of Amines 
Sekine, M; Satoh, M; Yamagata, H; Hata, T 
1980 
Yes 
Journal of Organic Chemistry
ISSN: 0022-3263
EISSN: 1520-6904 
AMER CHEMICAL SOC 
WASHINGTON 
45 
21 
4162-4167 
English 
WOS:A1980KL07000019 
Studies on the benzoylation of amines of dialkyl benzoylphosphonates (1A-F) were describedin detail. Stoichiometric reactions of diethyl benzoylphosphonate (IB) with a variety of amines (2a-i) gave amides as the main products along with diethyl phosphonate (4B) and a-(phosphoryloxy)benzyl phosphonate (5B). The yields of amides increased with the ratio of lB/2a-i. The use of hindered dialkyl benzoylphosphonates resulted in high yields of amides while the reaction rates decreased markedly. The benzoylations of n-propylamine (2d) with IB in various solvents having dielectric constants of 1.9-36.7 were conducted. The yields of N-npropylbenzamide (3d) and 5B were surprisingly almost constant. However, the reaction rates varied as follows. In nonpolar solvents such as n-hexane and cyclohexane benzoylation was remarkably rapid while the benzoylation in methylene chloride was much slower than that in other solvents used. Compound IB underwent smooth reaction with aliphatic amines but did not react with aromatic amines under the same conditions. Selective N-benzoylation of the bifunctional amine, ethanolamine, was achieved by means of diisopropyl benzoylphosphonate (1C) in tetrahydrofuran. The use of the hindered dialkyl benzoylphosphonate 1C resulted in poorer yieldsof amides in the case of the reaction with a hindered amine such as diethylamine, but higher yieldsof amides in the case of primary amines. Addition of triethylamine and 4-(dimethylamino)pyridine (DMAP) slightly accelerated the benzoylation, but yields of amides were similar to those in the absence of the catalysts. Optimum conditions for high yields of amides were proposed for the practical use of dialkyl benzoylphosphonates as the acylating agents in the present reaction. © 1980, American Chemical Society. All rights reserved.