大阪大学 · Chemistry
Shinobu Takizawa 교수의 연구실은 주로 수소결합 및 금속-유기 촉매를 활용한 고등차원적인 입체선택성 반응 개발에 초점을 맞추고 있습니다. 특히, 티타늄, 알루미늄, 바나듐을 포함한 전이금속을 이용한 다핵 촉매 시스템을 통해 축합 반응, 아자-Morita-Baylis-Hillman 반응, 산화적 결합 반응 등에서 높은 대칭성 파괴 효율을 달성하고 있습니다. 또한 축합된 축방향성 구조를 갖는 생합성물과 기능성 물질의 효능적인 합성 전략을 개발하고 있습니다. 이는 자연물 합성, 의약품 합성, 기능성 고분자 개발 등 응용 분야로 이어집니다.
표시된 성과는 수집된 데이터 기준으로 산출되며, 일부 차이가 있을 수 있습니다.
Immobile without support: The first synthesis of chiral Al-bridged and Ti-bridged polymers by a metal-mediated self-assembly of (R,R)-6,6′-bi(binol) (binol=1,1′-bi-2-naphthol), which bears two pairs of phenolic hydroxy groups at the opposite sides in the molecule, is described (see scheme, X=OH or O). The polymers are found to promote asymmetric Michael reaction and carbonyl–ene reaction with high enantioselectivity and can be reused. Supporting information for this article is available on the W
The P-chirogenic organocatalysts were found to promote the enantioselective aza-Morita-Baylis-Hillman reaction of ketimines derived from acyclic α-keto esters. In the P-chirogenic organocatalyzed aza-MBH reactions, α,α-disubstituted α-amino acid derivatives were obtained in high yields with high enantioselectivities (up to 97% ee).
An enantioselective organocatalyzed aza-MBH-type reaction of ketimines and allenoates has been developed. The present formal [2 + 2] cycloaddition produces highly functionalized azetidines with a chiral tetrasubstituted carbon stereogenic center in good to excellent yields and high enantioselectivities.
Teambildung: Die Titelreaktion bietet diastereoselektiven Zugang zu α-Alkyliden-γ-butyrolactonen mit bis zu 98 % ee (siehe Schema; Ts=4-Toluolsulfonyl). Der enantioselektive Prozess wird durch den Organokatalysator 1 katalysiert, der sowohl Lewis-basische als auch Brønsted-saure Einheiten enthält.
Preparation and structural analysis of chiral dinuclear vanadium(v) catalysts with high catalytic activity for the oxidative coupling of 2-naphthols are described.
Axially chiral compounds with rotationally constrained σ-bonds that exhibit atropisomerism are lucrative synthetic targets because of their ubiquity in functional materials and natural products. The metal complex-catalyzed enantioselective fabrication of axially chiral scaffolds has been widely investigated, and thus far, considerable progress has been made. Over the past two decades, we have developed a highly efficient strategy for constructing axially chiral biarenol derivatives using chiral
Abstract Enantioselective organocatalytic synthesis of tetrahydropyridines bearing a chiral tetrasubstituted carbon stereogenic center has been achieved. The spiro‐type monoaryl phosphine catalyst, ( R )‐SITCP, was found to promote the formal [4+2] cycloaddition of saccharin‐derived ketimines and α‐methyl allenoate to afford the corresponding six‐membered N‐heterocycles in high yields and excellent regioselectivities with up to 93% ee .
A unique spiro-type Brønsted acid-Lewis base organocatalyst has been developed. The new bifunctional organocatalyst promoted aza-Morita-Baylis-Hillman reactions to yield adducts with up to 98% ee.
Mixing of acryloylchloride, dienone 2, N,N-diisopropylethylamine with chiral organocatalyst 5a, which could simultaneously act as Brønsted and Lewis base catalysts, led to a one-pot amidation/Rauhut-Currier sequence, affording α-methylidene-γ-lactams 4. Catalyst 5a could be recovered and reused by acid/base extraction without any loss of catalytic activity in the stepwise protocol.
In recent years vanadium catalysis has been extended to a range of different and even complementary directions in asymmetric synthesis. Inspired by nature's way to activate both substrate and reagent in many cases, the design of efficient bifunctional and dinuclear vanadium catalysts has been achieved. Furthermore, vanadium catalysis has been an early field in which "hybrid catalysts" have been studied in detail by incorporation of oxovanadium complexes into proteins, thus giving artificial enzy
Vanadium-mediated enantioselective Friedel-Crafts (FC)-type reactions were established using the dinuclear vanadium complex (R(a),S,S)-1a. The vanadium complex promoted the FC-type reaction of imines with 2-naphthols or indoles to give corresponding adducts with high enantioselectivities.
A highly atom-economical, chemoselective, and stereoselective Lewis base (LB)-catalyzed dual umpolung domino Michael reaction between cyclohexadienones and alkynyl esters has been developed. PPh3, as a LB catalyst, afforded either the hydroindole-2-carboxylates or hydrobenzofuran-2-carboxylates 3 as a single diastereomer in high yields (up to 89%). An obtained product could be easily transformed to a (S*,S*,R*)-octahydroindole-2-carboxylic acid ((S*,S*,R*)-Oic) analogue.
