Pyrroles Larock indole synthesis

A type Ilac synthesis of functionalized pyrroles was developed that adapted the Larock indole synthesis <06OL5837>. For example, treatment of iodoacrylate 19 and trimethylsilylphenylacetylene 20 with palladium acetate led to the formation of pyrrole-2-carboxylate 21 with excellent regioselectivity. 19 was prepared by iodinating (N-iodosuccinimide) the corresponding commercially available dehydroamino ester. 

To make tryptophan analogs, Gronowitz and coworkers conducted a pyrrole annulation from an aminoiodopyrimidine utilizing the Larock indole synthesis conditions (see Section 1.10.) [80]. They prepared heterocondensed pyrrole 115 by treating 4-amino-5-iodopyrimidine 114 with trimethylsilyl propargyl alcohol under the influence of a palladium catalyst The regiochemical outcome was governed by steric effects. 

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