Nickel Nanoparticle Catalyzed Mono‐ and Di‐Reductions of gem‐Dibromocyclopropanes Under Mild, Aqueous Micellar Conditions

Abstract

Mild mono‐ and di‐hydrodehalogenative reductions of gem‐dibromocyclopropanes are described, providing an easy and green approach towards the synthesis of cyclopropanes. The methodology utilizes 0.5–5 mol % TMPhen‐nickel as the catalyst, which, when activated with a hydride source such as sodium borohydride, cleanly and selectively dehalogenates dibromocyclopropanes. Double reduction proceeds in a single operation at temperatures between 20–45 °C and at atmospheric pressure in an aqueous designer surfactant medium. At lower loading and either in the absence of ligand or in the presence of 2,2′‐bipyridine, this new technology can also be used to gain access to not only monobrominated cyclopropanes, interesting building blocks for further use in synthesis, but also mono‐ or di‐deuterated analogues. Taken together, this base‐metal‐catalyzed process provides access to cyclopropyl‐containing products and is achieved under environmentally responsible conditions.

Lipase-catalyzed esterification in water enabled by nanomicelles. Applications to 1-pot multi-step sequences

“…As shown in Scheme 5 , catalytic hydrogenation of cinnamic acid 44 in water in the presence of the Pd/C 27 led to intermediate acid 20. Subsequent lipase-catalyzed esterification with alcohol 45 gave gem -dibromocyclopropane 46, which was then reduced by nickel nanoparticles 28 to give product 47 in 65% overall isolated yield, all done, sequentially, in water.…”

Cascade Processes with Micellar Reaction Media: Recent Advances and Future Directions

“…The resulting cyclopropane containing biaryl was recovered by extraction with ethyl acetate, filtration, and flash chromatography. An isolated yield of 86% was achieved [ 117 ]. Using commercially available Pd-based catalysts, allylic substitution reactions (“Tsuji–Trost couplings”) have also been performed in aqueous TPGS-750-M micelles (1000 ppm of commercially available catalyst).…”