193215-80-4Relevant academic research and scientific papers
Intramolecular Diels-Alder additions to 2-benzopyran-3-ones; anti-selectivity induced by the phenylsulfonyl group
Bush, Edward J.,Jones, David W.,Ryder, Tracie C. L. M.
, p. 1929 - 1938 (2007/10/03)
Intramolecular Diels-Alder additions of the 2-benzopyran-3-ones 2d, 2e and 2f with an E-SO2Ph substituent on the dienophile (X = SO2Ph in 2) show greatly enhanced exo-addition of the tether than is shown in the absence of the E-SO2Ph group (X = H in 2). For 2e and 2f, exo-chain addition becomes preferred, and for 2d, endo-chain addition much less preferred, than in related cases with X = H. An E-CO2Me group on the dienophile is also effective in enhancing exo-chain addition, but less effective than an E-SO2Ph group. The adducts 4e and 4f undergo reductive elimination (5% Na-Hg) to give the diterpene related products 32 and 33 respectively.
