Carbamoyl Functionalized Bent para-Phenylenes via an Unexpected Reaction of the Burgess Reagent with α-Ketols.

The attempted dehydration of macrocyclic α-ketols with the Burgess reagent has resulted in the unexpected synthesis of carbamoylated, bent para-phenylene units. The same reaction with an acyclic analogue affords the intended dehydration product, indicating that the change in reactivity is conformationally controlled and a result of the bifunctional nature of the Burgess reagent.

Regioselective Synthesis of Unsymmetric Tetra- and Pentasubstituted Pyrenes with a Strategy for Primary C-Alkylation at the 2-Position.

The synthesis of 1,2,4,5- and 1,2,9,10-tetrasubstituted and 1,2,4,5,8-pentasubsutituted pyrenes has been achieved by initially functionalizing the K-region of pyrene. Bromination, acylation, and formylation reactions afford high to moderate levels of regioselectivity, which facilitate the controlled introduction of other functional groups about 4,5-dimethoxypyrene. Access to 4,5-dimethoxypyren-1-ol and 9,10-dimethoxypyren-1-ol enabled a rare, C-2 primary alkyl substitution of pyrene.