Rhodium-Catalyzed Asymmetric Hydroarylation of Diphenylphosphinylallenes with Arylboronic Acids

Abstract

Rhodium-catalyzed asymmetric hydroarylation of diphenylphosphinylallenes with arylboronic acids proceeded in high yields with high regio- and enantioselectivity to give chiral allylphosphine oxides of up to 98% ee. The structural determination of the key intermediate, a pi-allylrhodium complex, was successful to establish the catalytic cycle of the reaction.

Rhodium‐ and Palladium‐Catalyzed Asymmetric Conjugate Additions

“…Although the diastereoisomeric excesses are modest, this transformation can be applied on a range of di-and tripeptides [171]. The enantioselective protonation was also applied to the hydroarylation of diphenylphosphinylallenes [172]. Unlike the oxo-π-allylrhodium species in previous examples, the π-allylrhodium intermediate K can be protonated α or γ to the phosphorus center to give intermediates 121a and 121b, respectively.…”

Addition Reactions: Polar Addition

“…A π -allylrhodium ee complex has been identified as the key intermediate. 109 Rhodium(I)-catalysed inter-and intra-molecular addition of 3,4-dihydroquinazolines to unactivated alkenes has been reported. 110 The iridium-catalysed hydrosilylation of alkynes in the presence of 4,4 ,5,5 -tetramethylbiphosphinine (tmbp) has been explored and shown to proceed effectively to afford β-(E)-vinylsilanes with high selectivity in moderate to high yields, whereas de a similar hydrosilylation in the absence of tmbp produced β-(Z)-vinylsilanes.…”

Highly Regio- and Stereoselective Palladium(0)-Catalyzed Addition of Organoboronic Acids with 1,2-Allenic Sulfones, Sulfoxides, or Alkyl- or Aryl-Substituted Allenes in the Presence of Acetic Acid: An Efficient Synthesis of E-Alkenes

“…12 Under the catalysis of 10 mol% of tetrakis(triphenylphosphine)palladium, the reaction of phenyl propa-1,2-dienyl sulfone (2a) with phenylboronic acid (3a) in the presence of 100 mol% acetic acid failed to afford the addition products in dimethyl sulfoxide, dioxane, N,N-dimethylformamide, dimethylacetamide (DMA), or ethanol (Table 1, entries [1][2][3][4][5]. Fortunately, the same reaction afforded the hydroarylation product in solvents such as, acetone, acetonitrile, diethyl ether, toluene, dichloromethane, and tetrahydrofuran (Table 1, entries [6][7][8][9][10][11]. The best result was obtained in tetrahydrofuran, with product (E)-4aa forming in a regioselectivity of 91:9 (4aa/5aa) and a stereoselectivity of >99:1 [(E)-4aa/(Z)-4aa] ( Table 1, entry 11).…”

“…In the meantime, some palladium-catalyzed three-component coupling reactions involving boronic reagents and allenes have also been reported. 5 Very recently, Hayashi et al 6 reported the rhodium-catalyzed asymmetric addition of allenes with arylboronic acids affording (S)-2-aryl-3-(diphenylphosphinyl)alkenes in high yields and enantioselectivity. We wish to report here, as part of our research program on the chemistry of allenes, 7 the palladium-catalyzed addition of 1,2-allenic sulfones, sulfoxides, or alkyl-or aryl-substituted allenes with organoboronic acids in the presence of acetic acid.…”