Enantioselective palladium-catalyzed diboration of 1,1-disubstituted allenes

Abstract

Enantioselective palladium-catalyzed diboration of 1,1-disubstituted allenes is developed for the first time by employing a P-chiral monophosphorus ligand, BI-DIME.

Alkenyl Boronates: Synthesis and Applications

“…Hoveyda et al described the asymmetric protoboration of these substrates catalyzed by chiral NHCcopper complexes. [66] With the appropriate choice of reagents, boraformylation, [67] boroacylation, [68,69] boraalkoxyoxalylation, [69] or asymmetric diboration [70] have been reported with different copper(I)-phosphine catalytic systems.…”

Guanidine–Copper Complex Catalyzed Allylic Borylation for the Enantioconvergent Synthesis of Tertiary Cyclic Allylboronates

“…By using enantioenriched secondary alcohols, the corresponding vinyl‐substituted tertiary allylboronates can be prepared through a lithiation/borylation approach (Scheme a) . Alternatively, tertiary allylboronates can be obtained through conjugate borylation of dienones or dienoates, in a process catalyzed by a chiral copper complex (Scheme b), or through a palladium‐catalyzed diboration of allenes (Scheme c) . Remarkably, linear tertiary allylboronates have also been generated enantioselectively by allylic borylation of trisubstituted allylic carbonates using a Cu‐NHC catalyst (Scheme d) …”

Efficient Synthesis of (−)‐Corynoline by Enantioselective Palladium‐Catalyzed α‐Arylation with Sterically Hindered Substrates

“…Zuschriften very mild conditions. [11] Thee nantioselective palladium-catalyzed a-arylation [12] has provided one of the most attractive methods for constructing chiral compounds bearing benzylic all-carbon quaternary carbon centers.D espite its synthetic relevance, limitations remain. Most known catalytic systems only work well for non-hindered aryl halides,a nd only few efficient examples have been reported for aryl halides containing ortho substituents.F or example,h igh enantioselectivities were observed by Buchwald and co-workers [12m] for arange of nonhindered aryl halides in palladium-catalyzed arylations of ketone enolates when either BINAP or ac hiral dialkylphosphinobinaphthyl ligand was employed.…”

“…Among various palladium pre-cursors screened, Pd(OAc) 2 was the best in terms of yield (entries 3a nd [8][9][10]. Further screening of solvent and base demonstrated that toluene and NaOtBu were ag ood combination for ah igh yield and good enantioselectivity ( Table 1, entries [11][12][13][14][15][16][17][18][19][20]. Theb ase exerted as ignificant effect on the yield.…”