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.

Introducing Savie: A Biodegradable Surfactant Enabling Chemo- and Biocatalysis and Related Reactions in Recyclable Water

“…To demonstrate that the polyamide (i.e., PSar) of Savie does not interfere with various transition metal catalysts, reactions (shown in Scheme ) were performed using catalysts containing gold (e.g., Au-catalyzed alkyne hydration of a precursor to the antiviral drug pleconaril to afford ketone 21 ), ruthenium (e.g., Ru-catalyzed olefin metathesis to afford enone 22 ), nickel (e.g., Ni-catalyzed reduction of a gem -dibromocyclopropane to afford ester 23 ), and copper (e.g., asymmetric CuH-catalyzed reduction of a ketone to afford alcohol 24 , an intermediate toward fluoxetine) . In all cases, Savie performed as well as TPGS-750-M.…”

Towards a sustainable tomorrow: advancing green practices in organic chemistry

“…176 Lipshutz and coworkers harnessed the unique selectivity of Ni NPs for the selective mono-and di-hydrodehalogenative reductions of gem-dibromocyclopropanes. 282 Employing 5 mol% Ni(OAc) 2 with 3,4,7,8-(Me) 4 -1,10-phenthroline as a ligand, NaBH 4 as the hydrogen source, and pyridine as a base, resulted in selective dehalogenation of dibromocyclopropanes with good functional group tolerance. Furthermore, reducing the loading of Ni(OAc) 2 to 0.5 mol% ligated with 2,2′-bipyridine resulted in highly selective debromination, affording mono-brominated cyclopropanes as the sole product (Scheme 28).…”

“…Furthermore, reducing the loading of Ni(OAc) 2 to 0.5 mol% ligated with 2,2′-bipyridine resulted in highly selective debromination, affording mono-brominated cyclopropanes as the sole product (Scheme 28). 282…”

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

“…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. With water being the common denominator associated with chemoand bio-catalysis, virtually unlimited opportunities are available for combining each in 1-pot sequences.…”