A One-Pot Condensation of Pyrones and Enals. Synthesis of 1<i>H</i>,7<i>H</i>-5a,6,8,9-Tetrahydro-1-oxopyrano[4,3-<i>b</i>][1]benzopyrans
作者:Duy H. Hua、Yi Chen、Hong-Sig Sin、Maria J. Maroto、Paul D. Robinson、Steven W. Newell、Elisabeth M. Perchellet、James B. Ladesich、Jonathan A. Freeman、Jean-Pierre Perchellet、Peter K. Chiang
DOI:10.1021/jo970642d
日期:1997.10.1
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 1H,7H-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 6 Pi electrocyclic process. A remarkable asymmetric induction was obtained from a stereogenic center (C4) of the cyclohexenecarboxaldehyde [such as (S)-perillaldehyde] to provide only the C5a,7-trans tricyclic pyrone products. On the other hand, condensation of S-(formyloxy)- or 3-hydroxy-2-methyl-1-cyclohexene-carboxaldehydes with pyrones 1 gave mixtures of C5a,6-cis and -trans products. Several of the tricyclic pyrones strongly inhibit acetylcholinesterase activity, DNA synthesis, and tumor cell growth in vitro.