Diastereodivergent and Enantioselective 4 2 Annulations of γ-Butenolides with Cyclic 1-AzadienesReportar como inadecuado




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1

College of Pharmacy, Third Military Medical University, Chongqing 400038, China

2

Key Laboratory of Drug-Targeting and Drug Delivery System of the Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu 610041, China





*

Authors to whom correspondence should be addressed.



Academic Editor: Choon-Hong Tan

Abstract An asymmetric annulation reaction of γ-butenolides and cyclic 1-azadienes containing a 1,2-benzoisothiazole-1,1-dioxide motif has been studied, proceeding in a tandem Michael addition-aza-Michael addition sequence. Endo-type cycloadducts bearing fused tetracyclic skeletons were isolated in fair yields and with high enantioselectivity up to >99% ee under the catalysis of modified cinchona alkaloid DHQD2PHAL. Besides, exo-type diastereomers could be produced using β-isocupreidine β-ICD as the catalyst, though with moderate enantioselectivity. View Full-Text

Keywords: asymmetric organocatalysis; Brønsted base; cinchona alkaloids; butenolides; 1-azadienes; diastereodivergence asymmetric organocatalysis; Brønsted base; cinchona alkaloids; butenolides; 1-azadienes; diastereodivergence





Autor: Chao Li 1, Kun Jiang 1,* and Ying-Chun Chen 1,2,*

Fuente: http://mdpi.com/



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