Shigeki Matsunaga 교수

The design and application of linked-BINOLs investigated in our group are reviewed. Linked-BINOLs are a kind of semi-crown ether, thus they are flexible and applicable to metals having various ionic radii (Ga3+, Li+, Zn2+, In3+, La3+, and Y3+). The flexible linker segment, containing a coordinative heteroatom, has a crucial role in the construction of a unique and effective chiral environment that is not accessible from BINOL itself. Applications of linked-BINOLs to an epoxide opening reaction,

Abstract The synthesis of isoquinolines by site‐selective CH activation of O‐acyl oximes with a Cp*Co III catalyst is described. In the presence of this catalyst, the CH activation of various unsymmetrically substituted O‐acyl oximes selectively occurred at the sterically less hindered site, and reactions with terminal as well as internal alkynes afforded the corresponding products in up to 98 % yield. Whereas the reactions catalyzed by the Cp*Co III system proceeded with high site selectivity

The unique reactivity of [Cp*Co(III)] over [Cp*Rh(III)] was demonstrated. A cationic [Cp*Co(III)] catalyst promoted direct dehydrative C-H allylation with non-activated allyl alcohols, thus giving C2-allylated indoles, pyrrole, and phenyl-pyrazole in good yields, while analogous [Cp*Rh(III)] catalysts were not effective. The high γ-selectivity and C2-selectivity indicated that the reaction proceeded by directing-group-assisted C-H metalation. DFT calculations suggested that the γ-selective subst

No preactivation of the alcohol substrates is required in allylic, propargylic, and benzylic aminations catalyzed by a combination of commercially available Bi(OTf)3 and KPF6, mostly at room temperature (see scheme). The substitution reactions of readily accessible allylic, propargylic, and benzylic alcohols with sulfonamides, carbamates, and carboxamides give the desired amine products in up to 99 % yield.

Cooperative catalysis has proven to be a powerful strategy for realizing high reactivity and selectivity in asymmetric transformations. A variety of cooperative asymmetric catalysts have been developed over the last two decades. In this feature article, recent advances from our research on cooperative asymmetric catalysis, focusing on dinuclear Schiff base catalysis, are described. Design of dinuclear Schiff base catalysts and their applications in several asymmetric C-C and C-N bond-forming rea

An anti-selective direct catalytic asymmetric Mannich-type reaction is described. The Et(2)Zn/(S,S)-linked-BINOL 1 = 4/1 complex promoted a Mannich-type reaction of 2-hydroxy-2'-methoxyacetophenone (2) and N-diphenylphosphinoyl imines 3. Using as little as 0.25-1 mol % of the catalyst, we obtained Mannich adducts 4 in excellent yield (up to 99%), diastereoselectivity (anti/syn = up to >98/2), and enantiomeric excess (up to >99.5%). The anti-selectivity in the present system is complementary to t

The catalytic enantioselective meso-epoxide ring opening reaction with phenolic oxygen nucleophile (4-methoxyphenol) is described for the first time herein. This reaction was first found to be promoted by (R)-GaLB (Ga = gallium, L = lithium, B = (R)-BINOL), giving a variety of epoxide opening products in good to high ee (67−93% ee). However, chemical yield was only modest (yield 31−75%), despite the use of more than 20 mol % GaLB. This was due to the undesired ligand exchange between BINOL and 4

Full details of a direct catalytic asymmetric Mannich-type reaction of a hydroxyketone using a Et2Zn/(S,S)-linked-BINOL complex are described. By choosing the proper protective groups on imine nitrogen, either anti- or syn-beta-amino alcohol was obtained in good diastereomeric ratio, yield, and excellent enantiomeric excess using the same zinc catalysis. N-Diphenylphosphinoyl (Dpp) imine 3 gave anti-beta-amino alcohols in anti/syn = up to >98/2, up to >99% yield, and up to >99.5% ee, while Boc-i

Direct access: Sterically hindered vicinal quaternary carbon stereocenters were constructed by catalytic enantio- and diastereoselective double Michael reaction, providing straightforward access to dimeric hexahydropyrroloindole alkaloids. A Mn(4-fluorobenzoate)2/Schiff base complex and a Mg(OAc)2/benzoic acid system were used as catalysts. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typese

How pyridine got its tail: A new catalyst for the atom-economical C4-selective direct alkylation of pyridines is described. A combination of CoBr2 and LiBEt3H catalyzes the reaction of pyridines with 1-alkenes at 70 °C to give alkylation products with C4/C2 ratios of >20:1. Substrate/catalyst ratios of up to 4000, and a turnover number of 3440 were achieved.

Synthesis and application of alpha,beta-unsaturated N-acylpyrroles as highly reactive, monodentate ester surrogates in the catalytic asymmetric epoxidation and Michael reactions are described. alpha,beta-Unsaturated N-acylpyrroles with various functional groups were synthesized by the Wittig reaction using ylide 2. A Sm(O-i-Pr)(3)/H(8)-BINOL complex was the most effective catalyst for the epoxidation to afford pyrrolyl epoxides in up to 100% yield and >99% ee. Catalyst loading was successfully r

Now accessible: Sterically hindered vicinal tetrasubstituted carbon stereocenters, which are not accessible by asymmetric hydrogenation, were constructed by a catalytic asymmetric CC bond formation (see scheme; Dpp=diphenylphosphinoyl). By changing the Group 2 metal center, stereodivergent access to α,β-tetrasubstituted α,β-diamino esters was realized. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edi

Variabel: Sterisch gehinderte Produkte mit benachbarten tetrasubstituierten Kohlenstoffstereozentren, die nicht durch asymmetrische Hydrierung aufgebaut werden können, sind durch eine katalytische asymmetrische C-C-Verknüpfung zugänglich (siehe Schema; Dpp=Diphenylphosphinoyl). Der Wechsel des Gruppe-2-Metallzentrums ebnet einen stereodivergenten Weg zu α,β-tetrasubstituierten α,β-Diaminoestern. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such do

C2-selective indole C-H phosphoramidation was achieved through improved Cp*Co(III) catalysis. A cationic Co(III) species generated in situ from a Cp*CoI2-dimer showed the best catalytic activity, giving phosphoramidated indoles in 60-86% yield.