References
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- Cox , J. S.G. , Beach , J. E. , Blair , A. M.J.N. , Clarke , A. J. , King , J. , Lee , T. B. , Loveday , D. E.E. , Moss , G. F. , Orr , T. S.C. , Ritchie , J. T. and Sherd , P. 1970 . Advan. Drug Res. , 5 : 115
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- For example, reaction of the acid chloride (2a) with 33Z ethanolic Me2NH (1 eq.) in pyridine gave a 1:4 mixture of the chromone‐2‐carboxamide [(3a), 17Z] and the corresponding ethyl carboxylate ester
- Reaction of various acid chlorides (2) with 40Z aq. Me2NH (1 eq.), in the presence of NaHCO3, gave the carboxamides (3) (15–61Z) and the corresponding carboxylic acids (1)
- We obtained the known enamine (4), in 37Z yield, from a reaction of the acid chloride (2a) with excess (2 eq.) 40Z aq. Me2NH. Cyclisation of this enamine (4) to the chromone‐2‐carboxamide (3a) has been reported by Jerzmanowska, Z. and Kostka, K., Roczniki Chem., 1963, 37, 413
- An alternative to “use of the somewhat objectionable dimethylamine”, reported by Coppinger, G.M., J. Am. Chem. Soc., 1954, 76, 1372, involves formation of N,N‐dimethylcarboxamides by heating an acid chloride or anhydride in N,N‐dimethylformamide
- Scriven , E. F.V. 1984 . Comprehensive Heterocyclic Chemistry , Edited by: Boulton , A. J. and McKillop , A. Vol. 2 , 180 Oxford : Pergamon Press .
- Fellinger , L. L. and Audrieth , L. F. 1938 . J. Am. Chem. Soc. , 60 : 579
- Galat , A. and Elion , G. 1943 . J. Am. Chem. Soc. , 65 : 1566
- Ecker , D. J. , Loomis , L. D. , Cass , M. E. and Raymond , K. N. 1988 . J. Am. Chem. Soc. , 110 : 2457
- Dimethylammonium chloride was obtained by bubbling dry HCl through 33Z ethanolic Me2NH at ca. 0°C for 2 h. The solvent was evaporated in vacua and the crystalline salt was washed (Et2O) under N2 and dried in vacuo.