[3+2] Cycloadditions of α-acyl ketene dithioacetals with propargylamines: pyrrole synthesis in water

A series of 2,3,4-trisubstituted and 1,2,3,4-tetrasubstituted pyrroles were synthesized via [3+2] cycloaddition of α-acyl ketene dithioacetals (or related substrates) with commercially available propargylamines as 1,3-dipoles in water. Most of the reactions can be performed in the absence of an external base. The reaction of secondary amine (N-methylprop-2-yn-1-amine) with α-acyl ketene dithioacetals showed different reaction behaviours depending on the addition or absence of an external base.