Halogenated ketenes. 39. A new synthesis for substituted coumarins |
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| Authors: | William T. Brady C. H. Shieh |
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| Affiliation: | Department of Chemistry, North Texas State University, Denton, Texas 76203 U.S.A. |
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| Abstract: | A new general synthesis of substituted coumarins is described. The in situ cycloaddition of chloroketenes with α-methoxymethylenecyclohexanones yields (4 + 2) cycloaddition products, 3,4-dihydro-2-pyranones. The chlorine atom is reductively removed and methanol is spontaneously eliminated to yield the 5,6,7,8-tetra-hydrocoumarins. Dehydrogenation of these compounds results in good yields of the substituted coumarins. |
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