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Sensitized photooxygenation: IV. Synthesis and singlet oxygenation of ethyl 6‐ethyl‐3, 4‐dihydro‐2 H ‐pyran‐5‐carboxylate and ethyl 6‐isopropyl‐3, 4‐dihydro‐2 H ‐pyran‐5‐carboxylate
Author(s) -
ZeEn Huang,
XiaoGuang HiuKwong Leung Liang,
Leung HiuKwong,
YukYee Chan
Publication year - 1990
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.19900080215
Subject(s) - photooxygenation , chemistry , singlet oxygen , dioxetane , dihydropyran , isopropyl , steric effects , singlet state , pyran , tetra , medicinal chemistry , substrate (aquarium) , stereochemistry , photochemistry , organic chemistry , oxygen , catalysis , chemiluminescence , physics , nuclear physics , excited state , oceanography , geology
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.