Author
Y. Tokunaga
Bio: Y. Tokunaga is an academic researcher from Tohoku University. The author has contributed to research in topics: Intramolecular force & 1,3-Dipolar cycloaddition. The author has an hindex of 12, co-authored 50 publications receiving 394 citations.
Papers
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TL;DR: The electrolysis of the bromoacetates gave the debrominated compounds in good yields and the synthetic intermediate 49 of Ipecac and Corynanthe alkaloids was obtained in 88% yield in a highly stereoselective manner.
Abstract: [Ni(cyclam)](ClO(4))(2)-catalyzed indirect electroreduction of olefinic bromides produced six-membered compounds in low to high yields. The synthetic intermediate 49 of Ipecac and Corynanthe alkaloids was obtained in 88% yield in a highly stereoselective manner. Lactam 66, the synthetic precursor of tacamonine, was prepared in 49% yield as a mixture of two diastereoisomers. The electrolysis of the bromoacetates gave the debrominated compounds in good yields.
58 citations
TL;DR: In this article, the reaction of β-hydroxy or acetoxy sulfones with Sml2 in the presence of HMPA caused effectively reductive elimination to provide olefins.
55 citations
TL;DR: The radical cyclization of (±)-(E)-3-((2-(bromomethyl)butoxy)carbonyl)-prop-2-enoates (11) and (12) were carried out with (TMS) 3 SiH or Bu 3 SnH in the presence of AIBN.
Abstract: The radical cyclizations of (±)-(E)-3-((2-(bromomethyl)butoxy)carbonyl)- prop-2-enoates (11) and (12) and (±)-ethyl (E)-3-{N-[2-(bromomethyl)- butyl]-N-[2-(3-indolyl)ethyl]carbamoyl}prop-2-enoate (25) were carried out with (TMS) 3 SiH or Bu 3 SnH in the presence of AIBN. (-)-(2S)-2- ((tert-Butyldimethylsilyloxy)methyl)butan-1-ol (6), which was prepared by two different methods, was converted into (+)-25. The radical cycli- zation of(+)-25 produced piperidinone (18) as a diastereomeric mixture, which was transformed into tacamonine (1)
36 citations
TL;DR: A new synthetic methodology for construction of the A/B ring system of steroids was developed consisting of a 1,3-dipolar cycloaddition, followed by incorporation of a three-carbon unit; a facile total synthesis of (+)-testosterone was achieved via this strategy.
Abstract: A new synthetic methodology for construction of the A/B ring system of steroids was developed consisting of a 1,3-dipolar cycloaddition, followed by incorporation of a three-carbon unit; a facile total synthesis of (+)-testosterone was achieved via this strategy
30 citations
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11 Sep 2006TL;DR: It is shown that domino reactions initiated by oxidation or reduction or reduction, as well as other mechanisms, can be inhibited by various materials, such as Na6(CO3)(SO4), Na2SO4, Na2CO3, and so on.
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
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