Abstract

An expeditious metal-free heteroannulation reaction for pyrido[1,2-a]pyrimidines/imidazo[1,2-a]pyridines was developed in green solvent under mild reaction conditions by using three-component reaction of 2-chloroquinoline-3-carbaldehyde, malononitrile and nitroketen aminals, which obtained from the reaction between 1,1-bis(methylthio)-2-nitroethylene and diamines in green solvent under EtOH reflux conditions. This one-pot strategy is very simple and occurs in two steps. The present sequence is visualized as an environmentally benign process with excellent purity and high yields.

Graphic abstract

An efficient, useful and general procedure for the synthesis of pyrido[1,2-a]pyrimidines/imidazo[1,2-a]pyridines via a one-pot three-component reaction of 2-chloroquinoline-3-carbaldehyde, malononitrile/ethyl 2-cyanoacetate and nitroketen aminals under mild and catalyst-free conditions in excellent yields is described. The major advantages of this protocol are high yields, mild and catalyst-free conditions, short reaction times and application of green solvent.

中文翻译：

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通过Knoevenagel反应/氮杂-烯加成/分子内环化，有效获得吡啶并[1,2-a]嘧啶和咪唑并[1,2-a]吡啶

摘要

通过2-氯喹啉-3-甲醛的三组分反应，在温和的反应条件下，在绿色溶剂中开发了吡啶[1,2- a ]嘧啶/咪唑并[1,2- a ]吡啶的快速无金属杂环反应。，丙二腈和亚硝基缩醛，它们是由1,1-双（甲硫基）-2-硝基乙烯与二胺在绿色溶剂中于EtOH回流条件下反应制得的。这种一锅法非常简单，分两个步骤进行。本序列可视为具有优良纯度和高收率的对环境有益的过程。

图形摘要

通过2-氯喹啉-3-甲醛，丙二腈/一锅三组分反应制备吡啶并[1,2- a ]嘧啶/咪唑并[1,2- a ]吡啶的有效，通用方法描述了在温和且无催化剂的条件下以优异的收率得到的2-氰基乙酸乙酯和亚硝基缩醛。该方案的主要优点是高产率，温和且无催化剂的条件，较短的反应时间和绿色溶剂的应用。