Boration of an α,β-enone using a diboron promoted by a copper(I)–phosphine mixture catalyst

Creation of Nucleophilic Boryl Anions and Their Properties

“…33 On the other hand, Miyaura and Ishiyama suggested that mixing 32 and CuCl in the presence of LiCl and KOAc gave borylcopper species 33, where the resulting 33 could undergo ¢-borylation of ¡,¢-unsaturated carbonyls, monoborylation of alkynes, and substitution of allyl chloride (Scheme 9).…”

Highly Diastereo‐ and Enantioselective Cu‐Catalyzed Borylative Coupling of 1,3‐Dienes and Aldimines

“…Branched homoallylic amines are readily prepared in as yn-selective manner with high regio-, diastereo-and enantioselectivity.M oreover,t hese three-component coupling reactions feature good functional-group compatibility and easy access to the substrates and catalyst.Asymmetric allylation reactions [1] of imines have received increasing interests from the synthesis community [2] because enantioenriched homoallylic amine products are useful building blocks in organic synthesis and medicinal chemistry.[3] Copper catalysis is an efficient approach to promote the enantioselective addition of terminal allyl transmetalation reagents (e.g., with B, Si, and Sn) to imines, [4] however,C ucatalyzed asymmetric, nucleophilic addition to imines with functionalized (e.g., g-substituted) allyl metal reagents remain challenging.T his is probably due to inefficiencyo f the transmetalation event arising from increased steric hindrance,t he weak electrophilicity/reactivity of imines, and/or difficulties in predicting the regio-and stereochemical outcome of additions.N ew and efficient approaches to generating and utilizing functionalized allyl metal reagents in the presence of acopper catalyst hold promise for accessing complex homoallylic amines,a nd these methods will expand the application of catalytic asymmetric allylation chemistry.Since the seminal work of borylcopper catalysis reported by the Ito [5] and the Miyaura [6] groups,C u-catalyzed borylative coupling reactions have been recognized as an important method for generating boron-containing organocopper species in situ from an unsaturated hydrocarbon. [7] In this context, Hoveyda pioneered the use of boron-functional allylcopper intermediates in enantioselective allylation of aldehydes/ketones, [7f] allyllic esters, [7i] and enoates.…”

Highly Diastereo‐ and Enantioselective Cu‐Catalyzed Borylative Coupling of 1,3‐Dienes and Aldimines

“…Branched homoallylic amines are readily prepared in as yn-selective manner with high regio-, diastereo-and enantioselectivity.M oreover,t hese three-component coupling reactions feature good functional-group compatibility and easy access to the substrates and catalyst.Asymmetric allylation reactions [1] of imines have received increasing interests from the synthesis community [2] because enantioenriched homoallylic amine products are useful building blocks in organic synthesis and medicinal chemistry.[3] Copper catalysis is an efficient approach to promote the enantioselective addition of terminal allyl transmetalation reagents (e.g., with B, Si, and Sn) to imines, [4] however,C ucatalyzed asymmetric, nucleophilic addition to imines with functionalized (e.g., g-substituted) allyl metal reagents remain challenging.T his is probably due to inefficiencyo f the transmetalation event arising from increased steric hindrance,t he weak electrophilicity/reactivity of imines, and/or difficulties in predicting the regio-and stereochemical outcome of additions.N ew and efficient approaches to generating and utilizing functionalized allyl metal reagents in the presence of acopper catalyst hold promise for accessing complex homoallylic amines,a nd these methods will expand the application of catalytic asymmetric allylation chemistry.Since the seminal work of borylcopper catalysis reported by the Ito [5] and the Miyaura [6] groups,C u-catalyzed borylative coupling reactions have been recognized as an important method for generating boron-containing organocopper species in situ from an unsaturated hydrocarbon. [7] In this context, Hoveyda pioneered the use of boron-functional allylcopper intermediates in enantioselective allylation of aldehydes/ketones, [7f] allyllic esters, [7i] and enoates.…”