A natural light induced regioselective 6pi-electrocyclisation-oxidative aromatisation reaction: experimental and theoretical insights.
Stoichiometric intermolecular Pauson-Khand reactions of 4-(phenylethynyl)-6-methyl-2-pyrones with norbornene and dicobalt(0)octacarbonyl provide cyclopentenone products that undergo a facile 6pi-electrocyclisation-oxidative aromatisation transformation in the presence of natural light and oxygen, affording functionalised benzo[h]indeno[1,2-f]isochromene type products. The results are rationalised by theoretical studies, which confirm that the electrocyclisation process is favoured at C3 in the 2-pyrone ring system. The identity and precise arrangement of the 'trienyl' substituents control whether the electrocyclisation occurs in natural light.
Moulton
Benjamin E
BE
Department of Chemistry, University of York, Heslington, York, UK.
Dong
Hao
H
O'Brien
Ciara T
CT
Duckett
Simon B
SB
Lin
Zhenyang
Z
Fairlamb
Ian J S
IJ