Diastereoselective construction of tetrahydropyridine fused bicyclic structures via three-component domino reaction
Jie-Ping Wan1, Yunfang Lin, Qing Huang
1College of Chemistry and Chemical Engineering, Jiangxi Normal University , Nanchang 330022, PR China.
Abstract:
The three-component reactions of enals, electron-deficient alkynes, and hydroxyl-functionalized primary amines for the highly diastereoselective construction of dihydro-3H-benzo[4,5]oxazolo[3,2-a]pyridines, hexahydropyrido[2,1-b][1,3]oxazines, and tetrahydro-2H-oxazolo[3,2-a]pyridines have been achieved. Domino formation of one C-C, two C-N, and one C-O bonds are furnished in these reactions. This bis-annulation protocol allows for the synthesis of fused heterocyclic products of high structural diversity with variation not only of appended fragments but also the ring size of the central backbone.
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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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