Three-component synthesis of N-Boc-4-iodopyrroles and sequential one-pot alkynylation.

(Hetero)aryl-, alkenyl-, and selected alkyl-substituted acid chlorides can be efficiently coupled with N-Boc-protected propargylamine to produce ynones which are converted in a one-pot fashion to 2-substituted N-Boc-4-iodopyrroles. Upon addition of a further alkyne, another Sonogashira coupling can be carried out in a one-pot fashion. This sequentially Pd/Cu-catalyzed process represents a very mild and efficient entry to 2,4-disubstituted N-Boc-pyrroles.