Regioselectivity in the Intramolecular Heck Reaction of a Series of Cyclic Sulfonamides: An Experimental and Computational Study

Regioselectivity in the intramolecular Heck reaction of a series of N‐sulfonyl‐2,5‐dihydro‐3‐substituted pyrroles was studied. These substrates are unbiased in terms of the formed ring size of the new heterocycle. Results indicate that high levels of regioselectivity are observed under a range of conditions, and that there is an underlying propensity for carbon–carbon bond formation at the most hindered end of the alkene. For two examples (3‐Me and 3‐tBu), DFT calculations were performed and indicate that in both cases, the modelled transition state for carbopalladation is energetically lower for the experimentally preferred isomer.