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Effect of secondary MO interaction on the regiospecificity in the reactions of tf‐ionones with singlet oxygen
Author(s) -
Wu GuoSheng,
Tao Tao,
Hu Jun,
Zha ZhenChuan,
Wu BiQi
Publication year - 1993
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.19930110408
Subject(s) - chemistry , steric effects , singlet state , singlet oxygen , mndo , photochemistry , hydrogen atom abstraction , oxygen , hydrogen bond , hydrogen atom , hydrogen , oxygen atom , computational chemistry , stereochemistry , molecule , organic chemistry , atomic physics , excited state , physics , alkyl
The ene reactions of a‐ionones with singlet oxygen were examined to ascertain the effect of secondary MO interaction between the reactants on the reaction regiospecificity. Exclusive formation of 3‐hydroxy‐V‐ionones found in the reactions reveals favorable interaction of singlet oxygen with the acyclic fl‐hydrogen atom. On the other hand, no formation of 3‐hydroxy‐0‐ionones implies that the steric requirement was not met for the bond formation between zwitterionic perepoxide with Ci‐hydrogen in the process. The MMP21 and MNDO calculations indicate minus value of the secondary interaction energy for the acyclic a‐hydrogen abstraction and a repulsion between the oxygen with C 1 ‐hydrogen atom. Twisting tilting of the double bond may account for favorable attack of singlet oxygen on C3. An explanation of the excellent regiospecificity was addressed and placed in proper mechanic prospective.