Shinobu Takizawa

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.