Imidazolidine-based enamines

Bicyclic 1,4-dihydropyridines were successfully synthesized by Li et al. by the reaction of imidazolidine-based enamines 148 with CH acids 146/112 and aldehydes 147/151 in the presence of a weak base (Scheme 13.38) [63]. Cyclization of those products under basic conditions afforded the tetracyclic 1,4-dihydropyildme derivatives 150/153. One year later, this reactions scope was extended... 

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