Unexpected isocyanide-based three-component bicyclization for the stereoselective synthesis of densely functionalized
Qian Gao1, Wen-Juan Hao1, Feng Liu1
1School of Chemistry and Chemical Engineering, Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, Jiangsu Normal University, Xuzhou 221116, P. R. China. laotu@jsnu.edu.cn jiangchem@jsnu.edu.cn.
Abstract:
A novel three-component bicyclization strategy for the efficient synthesis of densely functionalized pyrano[3,4-c]pyrroles has been established from readily accessible 3-aroylacrylic acids, dialkyl acetylenedicarboxylates and isocyanides. The reaction pathway involves Huisgen 1,3-dipole formation, Passerini-type reaction, Mumm rearrangement and an oxo-Diels-Alder reaction sequence, resulting in continuous multiple bond-forming events including C-N, C-O and C-H bonds to rapidly build up molecular complexity.
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Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.

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