Selective Synthesis of the Aminobutadiene Intermediate and Mechanistic Analysis of 1,4-Dihydropyridine Formation Reaction in Water

Effect of Water in the Trimer‐Cyclisation of Alkynyl Ketone

“…In the synthesis of 1,4-DHP (1), trimethyl 1,3,5-benzenetricarboxylate (2) was identified as a side product. [8] As 2 did not contain nitrogen atoms derived from ammonium acetate, it was concluded that 2 was formed via a different cyclisation route that probably involved the elimination of amine. Therefore, we conducted the reaction in the absence of ammonium acetate by heating methyl propiolate with a morpholine-acetic acid salt (0.33 eq) in water.…”

“…In the synthesis of 1,4‐DHP ( 1 ), trimethyl 1,3,5‐benzenetricarboxylate ( 2 ) was identified as a side product [8] . As 2 did not contain nitrogen atoms derived from ammonium acetate, it was concluded that 2 was formed via a different cyclisation route that probably involved the elimination of amine.…”

“…Using water as a solvent in organic synthesis is important from the view of green chemistry, which intends to reduce environmental deterioration and the economic costs of reactions. We previously reported the synthesis of 1,4‐dihydropyridine (1,4‐DHP) compounds from propiolate esters and amine salts in water [6–8] . Here, we report a trimer‐cyclisation reaction that proceeded selectively in water.…”

“…We previously reported the synthesis of 1,4-dihydropyridine (1,4-DHP) compounds from propiolate esters and amine salts in water. [6][7][8] Here, we report a trimer-cyclisation reaction that proceeded selectively in water.…”