Výsledky vyhledávání - "Takayuki Karakasa"

A facile and efficient one-pot synthesis of thiochromans from bis(2-formylphenyl) disulfide and alkenols via iodine-promoted generation and subsequent intramolecular cycloaddition of ortho-thiobenzoquinone methides

Autor: Yosuke Matsuda, Takahiro Horikoshi, Takayuki Karakasa, Takao Saito, Takashi Otani

Publikováno v: Tetrahedron Letters. 44:6513-6517

Stereoselective synthesis of tetrahydrofuro- and tetrahydropyrano[3,2- c ]benzothiopyrans was achieved by intramolecular [4+2]cycloaddition of o -thiobenzoquinone methides that were generated in situ from bis(2-formylphenyl) disulfide and alkenols in

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::9c5630014149f761e929a0eb5c149c29
https://doi.org/10.1016/s0040-4039(03)01510-7

Zobrazit plný text záznamu

Thermal or Lewis acid-promoted electrocyclisation and hetero Diels–Alder cycloaddition of α,β-unsaturated (conjugated) carbodiimides: a facile synthesis of nitrogen-containing heterocycles

Autor: Takahiro Ohkubo, Masayuki Maeda, Takao Saito, Sadayoshi Satsumabayashi, Hideki Kuboki, Kensaku Tsuda, Takayuki Karakasa

Publikováno v: Journal of the Chemical Society, Perkin Transactions 1. :3065-3080

α,β-Diarylvinyl- and α-styryl-carbodiimides, prepared by the aza-Wittig reaction of iminophosphoranes with isocyanates, underwent either 6π-electrocyclisation upon heating or a Diels–Alder reaction under thermal or Lewis acid-promoted condition

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::33265a6dd7ab1f373bed1501097cfa6e
https://doi.org/10.1039/a805574b

Zobrazit plný text záznamu

Thermal and Lewis acid-promoted asymmetric hetero Diels–Alder reaction of a 1-thiabuta-1,3-diene system (thiochalcone) with chiral acrylic esters and N-acryloyl- and N-crotonyl-carboximides

Autor: Takayuki Karakasa, Eiji Furuno, Hiroya Fujii, Hirofumi Suda, Takao Saito, Kimiko Kobayashi

Publikováno v: J. Chem. Soc., Perkin Trans. 1. :1359-1362

Thermal and Lewis acid-promoted asymmetric hetero Diels–Alder reactions of the thiabutadiene 1 with the chiral dienophiles 2–5 derived from (–)-menthol, (+)-borneol and (–)-4-benzyloxazolidinone affords the optically active dihydrothiopyran d

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::e04143ffb8abc317dbb382afea563081
https://doi.org/10.1039/p19940001359

Zobrazit plný text záznamu

Kinetic Stability as Monomeric Forms of 2-Alkyl-5,6-dihydro-3-thioacetyl-2H-naphtho[1,2-b]thiopyrans

Autor: Satoshi Moriyama, Takayuki Karakasa, Takao Saito, Shinichi Motoki

Publikováno v: Bulletin of the Chemical Society of Japan. 66:2124-2127

2-Alkyl-5,6-dihydro-3-thioacetyl-2H-naphtho[1,2-b]thiopyrans (2) exist stably in the form of monomers at room temperature, whereas unsubstituented ones at the 2-position are apt to dimerize. Based on the X-ray analysis of (2g), UV spectral study of (

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::5744e3aafa768cda972dec4b58cea98f
https://doi.org/10.1246/bcsj.66.2124

Zobrazit plný text záznamu

ChemInform Abstract: Syntheses and Reactions of Conjugated Dienic Thioketones

Autor: Shinichi Motoki, Takayuki Karakasa, Satoshi Moriyama

Publikováno v: ChemInform. 22

5,6-Dihydro-2-phenyl-3-thiobenzoyl-2H-naphtho[1,2-b]thiin (8a) and the related dienic thioketones were synthesized in 3 steps starting from 2-(phenylthio)methylenetetralin-1-thione with chalcone, 4′-chrolochalcone, 4′-methoxychalcone, 2-cinnamoyl

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::d7dae1c9b544292b52809cba34579a37
https://doi.org/10.1002/chin.199105210

Zobrazit plný text záznamu

ChemInform Abstract: Intramolecular Hetero-Diels-Alder Reaction of 1-Thiabutadienes, 1-Aryl- 3-(2-(alkenyloxy)phenyl)propene-1-thiones and 2-(2-(Alkenyloxy) benzylidene)-3,4-dihydronaphthalene-1(2H)-thiones

Autor: Takao Saito, Shinichi Motoki, Takayuki Karakasa, Masumi Nagashima

Publikováno v: ChemInform. 22

α,β-Unsaturated thioketones 4, 5 and 9, which are formed in situ by thionation of the corresponding ketones, undergo intramolecular hetero Diels–Alder reactions with high regio- and diastereo-selectivities (trans/cis) to give dihydrothiopyran-fus

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::836a21296bae7396a402c2b11a0a9397
https://doi.org/10.1002/chin.199119179

Zobrazit plný text záznamu

ChemInform Abstract: Thermal and Lewis Acid Promoted Novel Asymmetric Hetero Diels-Alder Reactions of a 1-Thiabuta-1,3-diene System (Thiochalcones) with (-)- Dimenthyl Fumarate

Autor: Satoshi Hayashibe, Takayuki Karakasa, Shinichi Motoki, Hideo Kato, Teruki Matsushita, Takao Saito

Publikováno v: ChemInform. 22

Thermal and Lewis acid-promoted reactions of thiochalcones with (–)-dimenthyl fumarate gave two 3,4-cis-cycloadducts, 4 and 5, in good yields with 100%endo-diastereoselectivity and with a high level of diastereofacial selectivity. The major product

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::d647e870ea3784d1e5ebcc4df748c452
https://doi.org/10.1002/chin.199149173

Zobrazit plný text záznamu

ChemInform Abstract: Lewis Acid Promoted Hetero Diels-Alder Reaction of α,β- Unsaturated Thioketones

Autor: Takayuki Karakasa, Shinichi Motoki, Eiji Furuno, Teruki Matsushita, Takao Saito

Publikováno v: ChemInform. 24

α,β-Unsaturated thioketones 1 were regenerated from their precursors, the dithiine-type dimers 3, and readily underwent the Lewis acid-promoted hetero Diels–Alder reactions with a variety of carbonyl-activated dienophiles such as methyl acrylate

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::4fea632da144dff211112954c9427a1c
https://doi.org/10.1002/chin.199310210

Zobrazit plný text záznamu

Vyhledávací nástroje:

Upřesnit hledání