One-Pot Five-Component Synthesis of Spirocyclopenta[b]chromene Derivatives and Their Acid-Catalyzed Rearrangement
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https://figshare.com/articles/dataset/One_Pot_Five_Component_Synthesis_of_Spirocyclopenta_i_b_i_chromene_Derivatives_and_Their_Acid_Catalyzed_Rearrangement/2476417
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The reaction of the zwitterionic intermediate, generated in situ from either tert-butylisocyanide or cyclohexylisocyanide and acetylenedicarboxylates, with 3-cyanochromones is described, whereupon spirochromenofuran derivatives 5 or 6 were obtained in good yields. The subsequent acid-catalyzed rearrangement of the isolated 2-imino-spirochromenofurans 5 to 2-amino-spirochromenofurans 7 has also been studied. Rational mechanistic schemes for the formation of compounds 5, 6, and 7 are proposed. The structure elucidation of the products was accomplished by 1D and 2D NMR experiments and confirmed by X-ray crystallographic analysis. Full assignment of all 1H and 13C NMR chemical shifts has been unambiguously achieved with the aid of DFT/GIAO calculations.
创建时间：
2016-02-20
