Yuusaku Yokoyama

Pd-Catalyzed Benzylic C–H Amidation with Benzyl Alcohols in Water: A Strategy To Construct Quinazolinones

A novel method for the synthesis of 4-phenylquinazolinones via a palladium-catalyzed domino reaction of o-aminobenzamides with benzyl alcohols is developed. This protocol involves N-benzylation, benzylic C-H amidation, and dehydrogenation in water, which may play an important role in the smooth generation of the (η(3)-benzyl)palladium species by activation of the hydroxyl group of the benzyl alcohol.

Syntheses without protection: a three-step synthesis of optically active clavicipitic acid by utilizing biomimetic synthesis of 4-bromotryptophan

Abstract The optically active clavicipitic acid ( 4 ), an ergot alkaloid, was synthesized by a three-step sequence from 4-bromoindole ( 1 ). The reaction of 1 with dl -serine ( 2 ) in the presence of Ac 2 O followed by enzymatic kinetic resolution gave ( S )-4-bromotryptophan ( 3 ). The Heck reaction of 3 with 1,1-dimethylallylalcohol in aqueous media gave clavicipitic acid in one-pot.

Palladium-catalyzed cross-coupling reaction: Direct allylation of aryl bromides with allyl acetate

Abstract Various aryl bromides underwent a palladium-catalyzed cross-coupling reaction with allyl acetate in the presence of hexa-n-butylditin to give the allylated products in very high yields.

Palladium-catalyzed mono-N-allylation of unprotected anthranilic acids with allylic alcohols in aqueous media.

Palladium-catalyzed N-allylation of anthranilic acids 1a-j with allyl alcohol 2a in the presence of Pd(OAc)(2), sodium diphenylphosphinobenzene-3-sulfonate (TPPMS) in THF-H(2)O at room temperature gave only mono-N-allylated anthranilic acids 3a-j in good yields (70-98%). The reactions of 4-bromoanthranilic acid 1i with 2-methyl-3-buten-2-ol 2b showed complete chemoselectivity in N-allylation (neutral conditions) and C-vinylation (basic conditions). In our catalytic system, the keys to success are use of an unprotected anthranilic acid as a starting material and the presence of water in the reaction medium. The carboxyl group of anthranilic acid and water may play important roles for the smooth generation of the π-allyl palladium species by activation of the hydroxyl group of the allylic alcohol.

Total synthesis of optically active chanoclavine-I

The total synthesis of optically active clianochvine-I, an ergot alkaloid, was accomplished using palladium-catalyzed intramoleeular cyclization (Heck reaction) as a key step. The conjugate ester (6) was obtained in 2 steps from optically active 4-bmmotryptophan (10), and the cyclization of 6 proceeded smoothly without racemization to give the key intermediate, trieyelie tetrahydrobenz(c,d)indole derivative (7), in high yield. Copyright

Pd-catalyzed C–H activation in water: synthesis of bis(indolyl)methanes from indoles and benzyl alcohols

A method for the synthesis of bis(indolyl)methanes via palladium-catalyzed domino reactions of indoles with benzyl alcohols was developed. This protocol involves C3-benzylation of indoles and benzylic C–H functionalization in water.

Palladium-Catalyzed Benzylation of Unprotected Anthranilic Acids with Benzyl Alcohols in Water

Palladium-catalyzed benzylation of unprotected anthranilic acids with benzyl alcohols in the presence of Pd(OAc)(2) (5 mol %) and sodium diphenylphosphinobenzene-3-sulfonate (TPPMS, 10 mol %) in water at 120 °C for 16 h gave only dibenzylated anthranilic acids in good yields. Water may play important roles for the smooth generation of the (η(3)-benzyl)palladium species by activation of the hydroxyl group of the benzyl alcohol.

The ortho-substituted N,N-diacetylaniline as a selective acetylating reagent

Abstract Selective acetylation of the less hindered amino group in the presence of the more hindered amino group with the use of 2-trifluoromethyl- N , N -diacetylaniline 2c is described. This acetylation with 2c yielded the corresponding less hindered monoacetamide exclusively, simply, conveniently, and in good yields.

Chemoselective Benzylation of Unprotected Anthranilic Acids with Benzhydryl Alcohols by Water-Soluble Au(III)/TPPMS in Water

A novel and efficient method for the benzylation of unprotected anthranilic acids with benzhydryl alcohols using water-soluble Au(III)/TPPMS in water is developed. Water plays an important role in our catalytic system. This new protocol could be used for not only N-benzylation, but also chemoselective C-benzylation by the Friedel-Crafts reaction.

Fischer indolization of 2-sulfonyloxyphenylhydrazones: A new and practical approach for preparing 7-oxygenated indoles and application to the first synthesis of eudistomidin-A. (Fischer indolization and its related compounds. Part 28)☆☆☆

Abstract An efficient method for synthesis of 7-oxygenated indoles was established by Fischer indolization of the phenylhydrazones ( 10 ) with a sulfonyloxy group at the ortho -position. This method was applied to the first synthesis of the calmodulin antagonist eudistomidin-A ( 2 ).