Keiichiro Fukumoto

Bio: Keiichiro Fukumoto is an academic researcher from Tohoku University. The author has contributed to research in topics: Total synthesis & Enantioselective synthesis. The author has an hindex of 19, co-authored 184 publications receiving 1278 citations.

Synthesis of Chiral Intermediates of Quinine Alkaloids and (+)‐ Dihydroantirhine.

Abstract: (4R,5R)-2-Ethoxy-5-ethyl-4-methoxycarbonylmeth yl-3,4,5,6-tetrahydro-2H-pyran 3, which has been enantioselectively prepared, is converted into the cis-substituted lactone 11 by treatment with propanedithiol in the presence of boron trifluoride–diethyl ether. The product 11 is converted into the synthetic intermediate 7 of quinine alkaloids and the synthetic precursor 19 of (+)-dihydroantirhine 10.

A Novel Approach to Optically Active Des-A C-13 Ethyl Steroids.

Abstract: Optically active des-A C-13 ethyl steroids 17∼20 have been synthesized by thermolysis of the optically active alkenic benzocyclobutene 14 as a key process.

Chiral Construction of the Estrane Ring System by an Intramolecular Double Michael Reaction.

Abstract: Construction of the estrane ring system was achieved by the Intramolecular double Michael reaction as the key step. Heating of the α,β-unsaturated enone ester (18), prepared from the optically active indanone (4), with chlorotrimethylsilane, triethylamine, and zinc chloride produced three estrane derivatives (19), (22), and (25).

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.

The Diels--Alder reaction in total synthesis.

Abstract: The Diels-Alder reaction has both enabled and shaped the art and science of total synthesis over the last few decades to an extent which, arguably, has yet to be eclipsed by any other transformation in the current synthetic repertoire. With myriad applications of this magnificent pericyclic reaction, often as a crucial element in elegant and programmed cascade sequences facilitating complex molecule construction, the Diels-Alder cycloaddition has afforded numerous and unparalleled solutions to a diverse range of synthetic puzzles provided by nature in the form of natural products. In celebration of the 100th anniversary of Alder's birth, selected examples of the awesome power of the reaction he helped to discover are discussed in this review in the context of total synthesis to illustrate its overall versatility and underscore its vast potential which has yet to be fully realized.

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