A One-Pot Condensation of Pyrones and Enals. Synthesis of 1 H, 7 H-5a, 6, 8, 9-Tetrahydro-1-oxopyrano [4, 3-b][1] benzopyrans

…, EM Perchellet, JB Ladesich, JA Freeman…

Index: Hua, Duy H.; Chen, Yi; Sin, Hong-Sig; Maroto, Maria J.; Robinson, Paul D.; Newell, Steven W.; Perchellet, Elisabeth M.; Ladesich, James B.; Freeman, Jonathan A.; Perchellet, Jean-Pierre; Chiang, Peter K. Journal of Organic Chemistry, 1997 , vol. 62, # 20 p. 6888 - 6896

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Citation Number: 80

Abstract

Condensation of various 6-substituted 4-hydroxypyrones 1 with 1- cyclohexenecarboxaldehydes in the presence of l-proline in ethyl acetate gave high yields of substituted 1 H, 7 H-5a, 6, 8, 9-tetrahydro-1-oxopyrano [4, 3-b][1] benzopyrans. The reaction presumably occurs via the 1, 2-addition of the pyrone with the aldehyde followed by dehydration and then cyclization through a 6Π electrocyclic process. A remarkable ...