title: Chemistry of heterocyclic ketene aminals: construction of imidazo(pyrido)[1,2-a]pyridines and imidazo(pyrido)[3,2,1-ij][1,8]naphthyridines via DABCO-catalyzed tandem annulations.
abstract: 2-(2-Chloroaroyl)methyleneimidazolidines with four reactive sites show fascinating structural features and could be used as a new strategy for the synthesis of novel heterocycles. This paper presents our new findings in the reaction of 2-(2-chloroaroyl)methyleneimidazolidines with allenic esters affording functionalized imidazo(pyrido)[1,2-a]pyridines via DABCO-catalyzed tandem annulations. Of particular significance is the incorporation of an o-halo group into the aryl ring of 2-benzoylmethylene-imidazolidines to set up a convenient and general way for constructing unusual imidazo(pyrido)[3,2,1-ij][1,8]naphthyridines.
authors: State Key Laboratory Base of Eco-Chemical Engineering, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, PR China. liming928@qust.edu.cn
authors: Ming
authors: M
authors: Li
authors: Zhong-Min
authors: ZM
authors: Zhou
authors: Li-Rong
authors: LR
authors: Wen
authors: Zhong-Xuan
authors: ZX
authors: Qiu