Nobuaki Taniguchi

Bio: Nobuaki Taniguchi is an academic researcher from Tohoku University. The author has contributed to research in topics: Enantioselective synthesis & Michael reaction. The author has an hindex of 15, co-authored 64 publications receiving 539 citations. Previous affiliations of Nobuaki Taniguchi include Yale University & Baylor University.

Enantioselective synthesis of monofluorinated chiral building blocks from malonic acid

Abstract: A general method for the preparation of monofluorinated chiral building blocks has been developed by fluorination of methyl phenylmenthyl monoalkylmalonates using lithium hexamethyldisilazide and 1-fluoro-2,4,6-trimethylpyridinium triflate.

Stereoselective alkylation of dianions derived from chiral half-esters of monosubstituted malonic acids: asymmetric synthesis of α-alkyl α-amino acids and key synthetic intermediates for Hunteria and Aspidosperma indole alkaloids

Abstract: Substitution of the chiral half-esters of monosubstituted malonic acids with halides leads to the formations of mixtures of the diastereoisomeric alkyl- or benzyl-malonic half-esters. The (R)-isomers (13A and 15A–22A) were obtained from the phenylmenthyl half-ester 14 of methylmalonic acid in high diastereoisomeric excess. The same stereoisomers were also produced by reaction of the half-esters 9, 23 and 24 with methyl iodide. Their absolute configurations were determined by transforming the major products into the known α-alkyl α-amino acid derivatives 30, 33 and 35. The major product 43, prepared by allylation of the half-ester 9, was converted into two lactones 41 and 42, key intermediates for synthesis of indole alkaloids of the Hunteria and Aspidosperma types. The mechanism of the above alkylation is discussed.

Total synthesis of hydrocinchonidine and hydrocinchonine via photo-oxygenation of an indole derivative

Abstract: 3-Ethylpiperidin-4-one (9) has been stereoselectively converted into (±)-2-{2-[(3RS,4SR)-N-benzyloxycarbonyl-3-ethyl-4-piperidyl]ethyl}-3-formylmethylindole (20), whose ring transformation via photo-oxygenation produced the 4-acylquinoline (23). Optical resolution of (±)-hydrocinchotoxine (24), derived from (23), led to a formal total synthesis of (+)-hydrocinchonine (25) and (–)-hydrocinchonidine (26).

A stereoselective total synthesis of (±)-Δ9(12)-capnellene via the intramolecular Diels–Alder approach

Abstract: A formal total synthesis of (±)-Δ9(12)-capnellene 1 was achieved by the intramolecular Diels–Alder reaction of the triene 4

Deconjugation of α,β-unsaturated esters and an intramolecular Michael reaction of bis-α,β-unsaturated esters with trialkylsilyl trifluoromethanesulfonate in the presence of tertiary amine: synthesis of (±)-ricciocarpin A

Abstract: Treatment of the α,β-unsaturated esters 1, 6 and 8 with trialkylsilyl trifluoromethanesulfonate in the presence of a tertiary amine gave, via silyl dienol ethers, the corresponding deconjugated esters 3, 7 and 9 as the major products, respectively. Reaction of bis-α,β-unsaturated esters 12a and 12b with a trialkylsilyl trifluoromethansulfonate in the presence of a tertiary amine caused an intramolecular Michael reaction to produce the cyclopentanes 14a and 20a and the cyclohexanes 14b and 20b. Bicyclic compounds 21a and 21b formed by tandem Michael–Dieckmann or intramolecular Diels–Alder reaction were concurrently obtained. The cyclohexane derivative 14b was converted into the racemate of a sesquiterpene, (±)-ricciocarpin A 22.

Domino Reactions in Organic Synthesis

Abstract: Introduction Cationic domino reactions Anionic domino reactions Radical domino reactions Pericyclic domino reactions Photochemically induced domino processes Transition metal catalysis Domino reactions initiated by oxidation or reduction Enzymes in domino reactions Multicomponent reactions Special techniques in domino reactions