Stereoselective Tandem Bis-Electrophile Couplings of Diborylmethane

Abstract

A copper-catalyzed three-component linchpin coupling method for the stereoselective union of readily available epoxides and allyl electrophiles is disclosed. Transformations employ [B(pin)]2-methane as a conjunctive reagent, resulting in the formation of two C–C bonds at a single carbon center bearing a C(sp3) organoboron functional group. Products are obtained in 42–99% yield, and up to >20:1 dr. The utility of the approach is highlighted by stereospecific transformations entailing allylation, tandem cross coupling, and application to the synthesis 1,3-polyol motifs.

Cobalt-catalyzed deoxygenative triborylation of allylic ethers to access 1,1,3-triborylalkanes

“…The relative stereochemistry of 14 was assigned anti by oxidizing 14 to a 1,3-diol and comparing the stereochemistry of the 1,3-diol with the reported data (see Supplementary Fig. 7 for a plausible explanation of this obtained diastereoselectivity) 41 . The benzylic boronate in 14 selectively underwent palladium-catalyzed cross-coupling with 4-iodoanisole to afford alkylboronate 15 , which could further react with 2-thienyllithium to produce compound 16 in high isolated yield (Fig.…”

Selective C−C Coupling of Vinyl Epoxides with Diborylmethide Lithium Salts

“…The reactivity explored with diborylmethide lithium salts for C−C bond formation involves alkylation reactions with aryl‐ or alkyl halides (Scheme a) as well as boron‐Witting reactions with carbonyl compounds (Scheme b). The reactivity of diborylmethide lithium salts with electrophiles other than aldehydes/ketones or RX has not been explored, except for an attempt to contribute to the copper‐catalyzed one‐pot three‐component stereoselective coupling of epoxides with allyl electrophiles and bis[(pinacolato)boryl]methane (Scheme c) or palladium‐catalyzed coupling/dehydroboration (Scheme c)…”

Stereoselective Multicomponent Reactions in the Synthesis or Transformations of Epoxides and Aziridines

“…According to mechanistic studies the step of formation of the organocopper species determines the anti -selectivity of the product. The 1,3-hydroxy-homoallylboronates 26 obtained were proven to be very useful for further functionalization, such as the stereoselective synthesis of a key intermediate of the alkaloid (+)-allo-sedamine; this methodology was also successfully extended to a sequential four-step process to obtain 1,3-polyol motifs [39].…”