Cobalt‐Catalyzed Regiodivergent Ring‐Opening Dihydroboration of Arylidenecyclopropanes to Access Skipped Diboronates

Abstract

Ligand‐controlled regiodivergent cobalt‐catalyzed ring‐opening dihydroboration of arylidenecyclopropanes is developed to access synthetically versatile skipped diboronates with catalysts generated in situ from Co(acac)2 and dpephos or xantphos. A variety of arylidenecyclopropanes reacted with pinacolborane (HBpin) to form the corresponding 1,3‐ or 1,4‐diboronates in high isolated yields and with high regioselectivity. Skipped diboronate products from these reactions can undergo various transformations to allow selective installation of two different functional groups along alkyl chains. Mechanistic studies suggest that these reactions combine cobalt‐catalyzed ring‐opening hydroboration of arylidenecyclopropanes and hydroboration of homoallylic or allylic boronate intermediates.

Enantioselective Copper-Catalyzed Ring-Opening Diboration of Arylidenecyclopropanes to Access Chiral Skipped 1,4- and 1,3-Diboronates

“…Nevertheless, there are only a limited number of enantioselective ring-opening functionalization reactions of arylidenecyclopropanes, such as hydrocyanation, hydroamination, hydroformylation, hydrophosphinylation, and aminoalkylation . Recently, we reported ligand-controlled cobalt-catalyzed regiodivergent ring-opening dihydroboration of arylidenecyclopropanes with HBpin to synthesize 1,3- and 1,4-diboronates (Scheme C), but attempts to identify chiral cobalt catalysts for the asymmetric version of these reactions have been fruitless thus far. Therefore, we have turned our attention to other transition-metal catalysts for asymmetric ring-opening diboration reactions of arylidenecyclopropanes to access enantioenriched skipped diboronates.…”

Regioselective 1,n-Diborylation of Alkylidenecyclopropanes Enabled by Catalysis with a Spirocyclic NHC IrIII Pincer Complex

“…Alkylidenecyclopropanes (ACPs) are commonly used as valuable building blocks in transition metal-catalyzed ring-opening reactions owing to their unique structure and high reactivity . Although very rare examples of the cleavage of a proximal or a distal C–C single bond of the cyclopropane ring accompanied by the addition of a B–B bond to give 1,3-diborylated products have been reported (Scheme d), − the ring-opening 1,1-diborylation of ACPs has not been reported.…”

Solvent-free copper-catalyzed trisilylation of alkynes: a practical and atom-economical approach for accessing 1,1,1-trisilylalkanes

“…In continuation of our efforts in developing selective base-metal catalyzed synthesis of multi-organometallic compounds from readily accessible unsaturated hydrocarbons, 46–53 we became interested in identifying selective base metal catalysts for trisilylation of alkynes to access 1,1,1-trisilylalkane compounds. We envisioned that copper complexes would be potential catalysts to promote 1,1,1-trisilylation reactions of terminal alkynes because copper acetylide and copper hydride species could be formed in the reactions of terminal alkynes with hydrosilanes.…”