Copper-Catalyzed Borylstannylation of Alkynes with Tin Fluorides

Abstract

Tin fluorides were found to be suitable electrophiles for the copper-catalyzed borylstannylation of terminal alkynes with bis(pinacolato)diboron to afford cis-vic-boryl(stannyl)alkenes straightforwardly. A fluorine atom proved to play a pivotal role in generating a key catalytic intermediate, a borylcopper species, both in the induction period and in the s-bond metathesis step.

Copper‐Catalyzed Preparation of Alkenylboronates and Arylboronates

“…[144] Copper-catalyzed heteroboration involving the addition of tive for Cu-Bpin mediated borylstannylation (Scheme 25a). [145] The Xu Group have reported a copper-catalyzed regiodivergent cis-silaboration of different terminal alkylacetylenes to prepare both the two regioisomeric silyl bearing alkenylboronates selectively by tuning the Cu-sources (CuTC, copper isocaprylate) and P-ligands (PCy 3 , PPh t Bu 2 : L41) (Scheme 25b). [146] Unlike, the classical cis-selective 1,2-addition of silylboronic esters to alkynes, challenging trans-silaboration of internal aryl(alkyl) alkynes could be achieved recently by the contribution from Suginome Group to access tetra-substituted silyl-vinylboronates (Scheme 25b).…”

Borylation and Stannylation Reactions with Tuning of Lewis Acidity

“…Besides the insertion of unsaturated carbon linkages into a CÀ Sn bond of organostannanes, copper-catalyzed installation of a stannyl group was also achieved by employing a tin fluoride as a tin electrophile in three-component borylstannylation of alkynes. [31] We previously disclosed that this type of borylstannylation proceeded by use of a tin alkoxide, [32] albeit rather sluggish with terminal alkynes; a tin fluoride turned out to be effective for this purpose. We first carried out the reaction of diphenylacetylene with (pin)BÀ B(pin) using tributyltin fluoride as a tin electrophile in the presence of PCy 3 À CuCl catalyst to observe the stereoselective formation of a syn-borylstannylated product in 74 % yield (Scheme 31).…”

Halogenated salt assisted Cu-catalyzed asymmetric 1,4-borylstannation of 1,3-enynes: enantioselective synthesis of allenylstannes

“…Meanwhile, a tin reagent was demonstrated to be a suitable electrophile in Cu-catalyed borylstannylation of alkynes (by Takaki et al ) and alkenes (by our group). 13 …”