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Photolysis of α,β‐Epoxyketones: A Green Synthesis of β‐Hydroxyenones through Tandem H‐Abstraction, Ring Cleavage and Isomerisation
Author(s) -
Dalal Aarti,
Kumar Dinesh,
Kamboj Ramesh C
Publication year - 2015
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.201500201
Subject(s) - chemistry , photochemistry , photodissociation , hydrogen atom abstraction , isomerization , epoxide , moiety , ring (chemistry) , intramolecular force , hydrogen , stereochemistry , organic chemistry , catalysis
The photochemical behavior of various substituted epoxycarbonyl compounds consisting of more than one possible photo‐labile site (i.e. δ‐hydrogen, β‐hydrogen and epoxide ring) has been investigated. These compounds on photo‐irradiation produced the β‐hydroxyenones in an eco‐friendly green approach. Mechanistically, these photo‐transformations have been envisaged to occur via an intramolecular β‐hydrogen abstraction by the carbonyl group of benzoyl moiety to generate the 1,3‐biradical followed by epoxide ring opening that isomerizes into the photoproducts. The photolysis of the probed epoxy ketones didn’t furnish any photoproduct through δ‐hydrogen abstraction, whatsoever. This exclusive preference for β‐H abstraction over δ‐H abstraction by carbonyl group has been vindicated by the MM2 energy mini‐ mized program for the investigated photochemical substrates. The structures of these photoproducts were established from the analysis of their spectral parameters (IR, 1 H/ 13 C NMR and Mass) and single crystal X‐ray crystallography data.