Ryo Yazaki 교수

Direct catalytic asymmetric conjugate addition of terminal alkynes to alpha,beta-unsaturated thioamides under proton transfer conditions is described. Soft Lewis acid/hard Brønsted base cooperative catalysis is crucial for simultaneous activation of terminal alkynes and thioamides, affording the beta-alkynylthioamides in a highly enantioselective manner. Control experiments suggested that the intermediate copper thioamide enolate can work as Brønsted base to drive the catalytic cycle via proton

A direct catalytic asymmetric addition of allyl cyanide to ketones with a bimetallic catalytic system comprising (R,R)-Ph-BPE/[Cu(CH(3)CN)(4)]ClO(4)/LiOAr is described. Exclusive gamma-addition of allyl cyanide was observed, affording optically enriched tertiary alcohols bearing Z-configured alpha,beta-unsaturated nitriles. The reaction proceeded under proton-transfer conditions, utilizing soft Lewis acid/hard Brønsted base bifunctional catalysis. The applicability of the reaction to aromatic, h

We report that a hard Lewis base substantially affects the reaction efficiency of direct catalytic asymmetric gamma-addition of allyl cyanide (1a) to ketones promoted by a soft Lewis acid/hard Brønsted base catalyst. Mechanistic studies have revealed that Cu/(R,R)-Ph-BPE and Li(OC(6)H(4)-p-OMe) serve as a soft Lewis acid and a hard Brønsted base, respectively, allowing for deprotonative activation of 1a as the rate-determining step. A ternary catalytic system comprising a soft Lewis acid/hard Br

Direct catalytic asymmetric addition of allylic cyanides to N-diphenylphosphinoyl ketoimines with a bimetallic catalytic system comprising Ph-BPE/[Cu(CH3CN)4]ClO4/LiOAr is described. Intermediary alpha-adducts readily isomerized to afford synthetically useful alpha,beta-unsaturated nitriles bearing an optically active tetrasubstituted carbon. Applicability to aromatic, heteroaromatic, and aliphatic ketoimines exemplifies wide substrate generality. Transformation of the product into densely funct

Unnatural α-amino acids are invaluable building blocks in synthetic organic chemistry and could upgrade the function of peptides. We developed a new mode for catalytic activation of amino acid Schiff bases, serving as a platform for highly congested unnatural α-amino acid synthesis. The redox active copper catalyst enabled efficient cross-coupling to construct contiguous tetrasubstituted carbon centers. The broad functional group compatibility highlights the mildness of the present catalysis. No

Abstract A synthetic route to trans ‐configured tetrahydrothiophenes (THTs) through Fe(OTf) 3 ‐promoted [3+2] cycloaddition of donor–acceptor cyclopropanes with thionoesters was developed. The cycloaddition proceeded in high yield with high diastereoselectivity, affording transient α‐alkoxy THTs. Not only aromatic and aliphatic thionoesters, but also thionolactone were applicable to the present iron catalysis. Further transformation of the S,O‐ketal functionality of the product was achieved in a

Chemoselective iron-catalyzed dehydrogenative cross-coupling using 2-acylimidazoles is described. The addition of a phosphine oxide ligand substantially facilitated the generation of tert-butoxy radicals from di-tert-butyl peroxide, allowing for efficient benzylic C–H bond cleavage under mild conditions. Extensive mechanistic studies revealed that the enolization of 2-acylimidazole proceeded through dual iron catalyst activation, followed by subsequent chemoselective cross-coupling with a benzyl

A highly chemoselective conjugate addition of alcohols in the presence of amines is described. The cooperative nature of the catalyst enabled chemoselective activation of alcohols over amines, allowing the conjugate addition to soft Lewis basic α,β-unsaturated nitriles. Divergent transformation of the nitrile functionality highlights the utility of the present catalysis.

We developed a chemoselective catalytic activation of carboxylic acid for a 1e^- radical process. α-Oxidation of a variety of carboxylic acids, which preferentially undergo undesired decarboxylation under radical conditions, proceeded efficiently under the optimized conditions. Chemoselective enolization of carboxylic acid was also achieved even in the presence of more acidic carbonyls. Extensive mechanistic studies revealed that the cooperative actions of iron species and alkali metal

A detailed study of the direct catalytic asymmetric conjugate addition of terminal alkynes to α,β-unsaturated thioamides is described. A soft Lewis acid/hard Brønsted base cooperative catalyst, comprising [Cu(CH(3)CN)(4)]PF(6), bisphosphine ligand, and Li(OC(6)H(4)-p-OMe) simultaneously activated both substrates to compensate for the low reactivity of copper alkynylide. A series of control experiments revealed that the intermediate copper-thioamide enolate functioned as a Brønsted base to genera

A concise enantioselective synthetic route to a potent GPR40 agonist AMG 837 is described. The crucial catalytic asymmetric conjugate addition of terminal alkyne was promoted by a soft Lewis acid/hard Brønsted base cooperative catalyst, allowing efficient construction of the requisite stereogenic center. The thioamide functional group is key to both activation in asymmetric alkynylation and facile transformation into carboxylic acid.

A new strategy, a transient homocoupling dimer strategy, for direct catalytic oxidative cross-enolate coupling reactions is developed. Cross-enolate coupling products bearing a (contiguous) tetrasubstituted carbon center were obtained chemoselectively without the need for stoichiometric amounts of strong bases/metal oxidants, and thus, the present catalysis provides a general method for the synthesis of unnatural α,α-disubstituted amino acid motifs. The distinct transformation of azlactone and 2

We developed a catalytic aerobic method to synthesize α,α-disubstituted α-amino acids through cross-dehydrogenative coupling of azlactones. Combining an iron catalyst with a bisoxazolidine ligand resulted in high catalytic performance, and cross-coupling with an indole proceeded smoothly under aerobic conditions. A wide variety of α-aryl and aliphatic amino acid derived azlactones were applied to the present catalysis. In addition, a quaternary carbon could be constructed using oxindole and benz

Abstract A highly chemoselective conjugate addition of alcohols in the presence of amines is described. The cooperative nature of the catalyst enabled chemoselective activation of alcohols over amines, allowing the conjugate addition to soft Lewis basic α,β‐unsaturated nitriles. Divergent transformation of the nitrile functionality highlights the utility of the present catalysis.