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Conversions of Coumarins Accompanied by Intermediate Opening and Recyclization of the Lactone Ring. 2. Study of the Interaction of Malonic Acid Hydrazide and Amide Derivatives with 3-Acyl(3-cyano, 3-ethoxycarbonyl)Coumarins

“…Study of the interaction of 3-acyl(ethoxycarbonyl)coumarins with malonic acid dihydrazide under the conditions of the Michael reaction has shown that this reaction occurs analogously to the conversion of 3-acyl(ethoxycarbonyl)coumarins into 3-cyanocoumarins discovered by us previously [2,3] with the formation of coumarin-3-carboxylic acid hydrazide 2.…”

“…The composition of the products essentially depends on the structure of the initial coumarin. In the case of coumarins unsubstituted in the benzene ring, and also their 6-methyl (6-Br) or 8-OMe derivatives, the salicylidene derivatives of coumarin-3-carboxylic acid hydrazides 4a-d predominate among the reaction products [4]. In the case of 3-ethoxycarbonyl(acetyl)coumarins the formation of the corresponding N,N'-biscoumarinoyl-2-hydrazines 3a-c was noted.…”

“…The somewhat contradictory picture is not clarified by adding in the results of the reaction of nitrogencontaining malonic acid derivatives with 3-substituted coumarins [4,6,7]. According to these data, unlike malondiamide, on interacting such derivatives as ethyl malonate monoamide and cyanoacetamide with 3-Z-substituted coumarins (Z = CN, COMe, COPh, COOEt) in the presence of bases, the process stops at the stage of forming the addition product at position 4 of the initial coumarin [7,8], though in the latter case [8] the conditions of carrying out the reaction were completely analogous to those used by us when studying the interaction of malondiamide with 3-substituted coumarins.…”

“…However we were unsuccessful in isolating the Michael adduct from the reaction mixture, since the reaction proceeded through opening of the coumarin lactone ring with subsequent recyclization and led practically to one product, 3-ethoxycarbonylcoumarin, which corresponds completely to the process observed in the case of forming 3-cyanocoumarins [2] and derivatives of coumarin-3-carboxylic acid hydrazide [4]. The data under consideration belong to a coumarin derivative containing an electron-withdrawing substituent at position 3 of the ring.…”

Transformations of coumarins accompanied by intermediate opening and recyclization of the lactone ring 3.* Study of the reactions of 3-ethoxy-carbonylcoumarins with cyanoacetyl-hydrazines by NMR spectroscopy

“…In a continuation of earlier researches in which the reaction of 3-ethoxycarbonylcoumarin 1 with cyanoacetylhydrazines 2 was studied by mass spectrometry [2,3] we have investigated the reaction by 1 H NMR spectroscopy directly in the tube used to record the spectra. As second component of the reaction we used both cyanoacetylhydrazine 2a itself and its isopropylidene derivative 2b.…”