Alkynes and nitriles participate as electrophiles in numerous heterocycle synthesis reactions, being attacked by a wide variety of nucleophiles.

A) The nucleophilic-electrophilic character of propanedinitrile and alpha-aminoketones allows the preparation of pyrroles , let's see an example.

pyrrole cyclization sp synthesis


pyrrole synthesis cyclization sp mechanism

B) In this second example we put into play thiourea, which reacts with alphabromonitrile yielding thiazole.

synthesis thiazole cyclization sp

thiazole synthesis sp cyclization mechanism

C) Intramolecular cyclization in which the alcohol acts as a nucleophile and the alkyne as an electrophile.

furan synthesis sp cyclization


furan synthesis sp cyclization mechanism

No thoughts on “Cyclization on sp carbons”