Kiyofumi Inamoto

Palladium-Catalyzed Synthesis of 2-Substituted Benzothiazoles via a C−H Functionalization/Intramolecular C−S Bond Formation Process

Catalytic synthesis of 2-substituted benzothiazoles from thiobenzanilides was achieved in the presence of a palladium catalyst through C-H functionalization/C-S bond formation. This method features the use of a novel catalytic system consisting of 10 mol % of Pd(II), 50 mol % of Cu(I), and 2 equiv of Bu4NBr that produced variously substituted benzothiazoles in high yields with good functional group tolerance.

Palladium-Catalyzed Intramolecular Amidation of C(sp2)−H Bonds: Synthesis of 4-Aryl-2-quinolinones

A catalytic synthetic approach for the synthesis of 2-quinolinone compounds through a Pd-catalyzed C(sp(2))-H functionalization/intramolecular amidation sequence is described. The cyclization process efficiently proceeds in the presence of a catalytic amount of PdCl(2) and Cu(OAc)(2) under an O(2) atmosphere, providing practical access to a range of variously substituted 4-aryl-2-quinolinones.

Ruthenium-catalyzed carbonylative C-H cyclization of 2-arylphenols: a novel synthetic route to 6H-dibenzo[b,d]pyran-6-ones.

Catalytic carbonylative C-H cyclization of 2-arylphenols can be achieved in the presence of a ruthenium-based catalytic system. The process proceeds efficiently under balloon pressure of CO and produces variously substituted 6H-dibenzo[b,d]pyran-6-one compounds, typically in good to high yields. Functional groups such as the alkoxycarbonyl and acetyl groups as well as halogen atoms (F, Cl, and Br) are well tolerated during the reaction.

A copper-based catalytic system for carboxylation of terminal alkynes: synthesis of alkyl 2-alkynoates.

An efficient coupling of terminal alkynes and CO(2) in the presence of alkyl halides can be achieved under ambient conditions using a copper/phosphine catalyst system, providing facile access to a variety of functionalised alkyl 2-alkynoates.

Synthesis of 3-Carboxylated Indoles through a Tandem Process Involving Cyclization of 2-Ethynylanilines Followed by CO2 Fixation in the Absence of Transition Metal Catalysts

In this study, a facile synthesis of 3-carboxylated indoles involving a tandem-type cyclization of 2-ethynylanilines and subsequent CO2 fixation at the 3-position of the indole ring is realized. The reaction proceeds efficiently at 65 °C under 10 atm of CO2, giving rise to variously substituted 3-carboxylated indoles, generally in high yields. An inorganic base, such as K2CO3, is the only reagent required, and the addition of transition metal catalysts is not necessary. The method provides a novel, simple, and promising strategy for CO2 fixation in the research field of heterocyclic chemistry.

Total Synthesis of Optically Active Lycopladine A by Utilizing Diastereoselective Protection of Carbonyl Group in a 1,3-Cyclohexanedione Derivative

We successfully synthesized two enantiomers of bicyclic enones, (7R,7aR)- and (7S,7aS)-9, from the hemiacetal 2a, which we first synthesized from the symmetrical diketone 1a via diastereoselective carbon-oxygen bond formation between one of the carbonyl groups and the chiral alcohol on the C2 side chain in a 2,2-disubstituted 1,3-cycloalkanedione derivative. We also report the total synthesis of natural (+)-lycopladine A [(+)-6] from (7R,7aR)-9 and the formal synthesis of unnatural (-)-lycopladine A [(-)-6] from (7S,7aS)-9.

Rhodium-Catalyzed Cyclization of 2-Ethynylanilines in the Presence of Isocyanates: Approach toward Indole-3-carboxamides

Catalytic synthesis of indole-3-carboxamides from 2-ethynylanilines and isocyanates was achieved in the presence of a rhodium catalyst through a tandem-type, cyclization-addition sequence. This tandem-type process can be performed under mild reaction conditions, affording 2,3-disubstituted indoles in a one-pot manner generally in good to excellent yields. The broad substrate scope and good functional group compatibility make the method highly efficient and widely applicable, providing a facile and entirely novel route toward variously substituted indole-3-carboxamides.

Development of Diastereoselective Birch Reduction-Alkylation Reactions of Bi- and Tricyclic β-Alkoxy-α,β-unsaturated Ketones

Diastereoselective Birch reduction-alkylation reactions of bicyclic beta-alkoxy-alpha,beta-unsaturated carbonyl compounds and tricyclic analogues were investigated. Although the relative configuration of the product was altered according to the structure of the starting material, stereoselectivity of the reaction could be accounted for by similar reaction pathways. The product from the tricyclic beta-alkoxy-alpha,beta-unsaturated carbonyl compound corresponded to the trichothecene skeleton.

Palladium-Catalyzed Highly Chemoselective Intramolecular C-H Aminocarbonylation of Phenethylamines to Six-Membered Benzolactams.

A palladium-catalyzed highly selective intramolecular C-H aminocarbonylation of Br-functionalized phenethylamines in the presence of CO was achieved while leaving the C-Br bond unreacted to afford six-membered benzolactams with good to high yields. The remaining C-Br group in the cyclized product was successfully used as a reactive center for further functionalization through various palladium-catalyzed coupling reactions.

Palladium catalyzed arylation of malonate accompanying in situ dealkoxycarbonylation

One-pot conversion of aryl halides into aryl acetates was achieved by the palladium catalyzed arylation of malonate accompanying in situ dealkoxycarbonylation of aryl malonates using Cs2CO3 as a base and as a catalyst.