Abstract
In this study, the synthesis of a series of novel four-fused-ring chromeno-benzoxepinones is described. The reaction of 1-benzoxepin-5-ones with salicylaldehydes mediated by 1,4diazabicyclo[2,2,2]octane (DABCO) involves domino reactions including an oxa-Michael reaction, an aldol condensation and dehydration in a one-pot sequence to yield the target compounds in fairly good yields.
Highlights
The reactions of salicylaldehydes with α,β-unsaturated cyclic carbonyl compounds catalyzed by base to undergo the domino oxa-Michael and aldol condensation to provide an easy access to a variety of chromene derivatives have been documented in the literature
Our synthetic strategy is based on the reaction of the key intermediate 1-benzoxepin-5-ones, with further salicylaldehydes, mediated by 1,4-diazabicyclo[2,2,2]octane (DABCO) (Scheme 2)
All title compounds have been fully characterized by spectral data such as 1H-NMR, 13C-NMR and HRMS
Summary
The oxa-Michael reaction has become a useful, concise and efficient tool for the synthesis of oxycyclic compounds, and was recently reviewed by Nising et al.1 the reactions of salicylaldehydes with α,β-unsaturated cyclic carbonyl compounds catalyzed by base to undergo the domino oxa-Michael and aldol condensation to provide an easy access to a variety of chromene derivatives have been documented in the literature.
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