Premium
Peri‐selective photocycloadditions of methyl 2‐pyrone‐5‐carboxylate with unsaturated cyclic ethers
Author(s) -
Shimo Tetsuro,
Iwakiri Tsuneaki,
Somekawa Kenichi,
Suishu Takaaki
Publication year - 1992
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570290136
Subject(s) - chemistry , cycloaddition , mndo , carboxylate , adduct , medicinal chemistry , excited state , stereochemistry , organic chemistry , molecule , catalysis , physics , nuclear physics
Photosensitized cycloaddition reaction of methyl 2‐pyrone‐5‐carboxylate ( 1 ) with 2,3‐dihydrofuran gave cis‐ exo‐ and cis ‐endo‐[2 + 2] cycloadducts across the C 3 ‐C 4 double bond in 1 , and a [4 + 2] cycloadduct which was different in addition‐orientation from the Diels‐Alder adducts. Each [2 + 2] cycloadduct was obtained by the use of sensitizers having different triplet energies. Photosensitized reactions of 1 with 3,4‐dihydro‐2 H ‐pyrans afforded cis ‐endo‐[2 + 2] cycloadducts, respectively. The photocycloaddition mechanism was also explained from the excited state of 1 calculated by means of MNDO‐Cl method.