New preparations of crystalline Vilsmeier reagent (VR) and dichloromethyl propyl or butyl ether were developed. The methods are environmentally benign and applicable to large-scale synthesis. Formylations of 1H-pyrrole-2-carboxylates were achieved with these reagents, regioselectively affording the 4-formyl and 5-formyl derivatives in nearly quantitative yields.

中文翻译：

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吡咯-2-羧酸的区域选择性甲酰化：结晶维尔斯迈尔试剂与二氯甲基烷基醚

开发了结晶维尔斯迈尔试剂（VR）和二氯甲基丙基或丁基醚的新制剂。该方法对环境无害，可用于大规模合成。用这些试剂实现1 H-吡咯-2-羧酸酯的甲酰化，区域选择性地以接近定量的产率提供4-甲酰基和5-甲酰基衍生物。