Acid, silver, and solvent-free gold-catalyzed hydrophenoxylation of internal alkynes.

A range of arylgold compounds have been synthesized and investigated as single-component catalysts for the hydrophenoxylation of unactivated internal alkynes. Both carbene and phosphine-ligated compounds were screened as part of this work, and the most efficient catalysts contained either JohnPhos or IPr/SIPr. Phenols bearing either electron-withdrawing or electron-donating groups were efficiently added using these catalysts.

Phospha-Michael additions to activated internal alkenes: steric and electronic effects.

The addition of P(O)-H bonds to internal alkenes has been accomplished under solvent-free conditions without the addition of a catalyst or radical initiator. Using a prototypical secondary phosphine oxide, a range of substrates including cinnamates, crotonates, coumarins, sulfones, and chalcones were successfully functionalized. Highly activated acceptors such as isopropylidenemalononitrile and ethyl 2-cyano-3-methyl-2-butenoate underwent the phospha-Michael reaction upon simple trituration of the reagents at room temperature, whereas less activated substrates such as ethyl cinnamate and methyl crotonate required heating (>150 °C) in a microwave reactor to achieve significant consumption of the starting alkenes.