Title compound 2b and 2c were synthesized via the condensation of 1, 3-dibromopropane with the appropriate β-keto ester under mildly basic condition. Photooxygenation of them under singlet oxygenation condition gives two kinds of product, namely, dioxetane-product and ene-product, with polar solvents, favoring the formation of the former. Comparison of the present study with that of the 6-methyl substrate 2a indicates that the effect of steric hindrance at the 6-position is significant, but not in a simple linear relationship to the reaction.

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Volume8, Issue2

March 1990

Pages 182-190

Sensitized photooxygenation: IV. Synthesis and singlet oxygenation of ethyl 6-ethyl-3, 4-dihydro-2H-pyran-5-carboxylate and ethyl 6-isopropyl-3, 4-dihydro-2H-pyran-5-carboxylate

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Sensitized photooxygenation: IV. Synthesis and singlet oxygenation of ethyl 6-ethyl-3, 4-dihydro-2H-pyran-5-carboxylate and ethyl 6-isopropyl-3, 4-dihydro-2H-pyran-5-carboxylate

Abstract

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