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2-Iodoxybenzenesulfonic Acid as an Extremely Active Catalyst for the Selective Oxidation of Alcohols to Aldehydes, Ketones, Carboxylic Acids, and Enones with Oxone 査読有り 国際誌

Uyanik, M; Akakura, M; Ishihara, K

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   131 巻 ( 1 ) 頁： 251 - 262   2009年1月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the American Chemical Society  

Electron-donating group-substituted 2-iodoxybenzoic acids (IBXs) such as 5-Me-IBX (1g), 5-MeO-IBX (1h), and 4,5-Me2-IBX were superior to IBX 1a as catalysts for the oxidation of alcohols with Oxone (a trademark of DuPont) under nonaqueous conditions, although Oxone was almost insoluble in most organic solvents. The catalytic oxidation proceeded more rapidly and cleanly in nitromethane. Furthermore, 2-iodoxybenzenesulfonic acid (IBS, 6a) was much more active than modified IBXs. Thus, we established a highly efficient and selective method for the oxidation of primary and secondary alcohols to carbonyl compounds such as aldehydes, carboxylic acids, and ketones with Oxone in nonaqueous nitromethane, acetonitrile, or ethyl acetate in the presence of 0.05-5mol%of 6a, which was generated in situ from 2-iodobenzenesulfonic acid (7a) or its sodium salt. Cycloalkanones could be further oxidized to α,β- cycloalkenones or lactones by controlling the amounts of Oxone under the same conditions as above. When Oxone was used under nonaqueous conditions, Oxone wastes could be removed by simple filtration. Based on theoretical calculations, we considered that the relatively ionic character of the intramolecular hypervalent iodine-OSO2 bond of IBS might lower the twisting barrier of the alkoxyperiodinane intermediate 16. © 2009 American Chemical Society.

DOI： 10.1021/ja807110n

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Catalytic Diastereoselective Polycyclization of Homo(polyprenyl)arene Analogues Bearing Terminal Siloxyvinyl Groups 査読有り

Muhammet Uyanik, Kazuaki Ishihara, Hisashi Yamamoto

Organic Letters   8 巻 ( 24 ) 頁： 5649 - 5652   2006年11月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

Highly diastereoselective polycyclization of homo(polyprenyl)arene analogues bearing terminal siloxyvinyl groups was catalyzed by tin(IV) chloride (10 mol %). The cyclizations of tert-butyldiphenylsilyl and triisopropylsilyl polyenol ethers gave 4(equatorial)- and 4(axial)-siloxypolycycles as major isomers, respectively. The strong nucleophilicity of pro-C(9), a (6E) geometry, and a bulky silyl group effectively favored the 4-preference, whereas the weak nucleophilicity of pro-C(9), a (6Z)-geometry, and less steric hindrance of a silyl group favored the 4-preference.

DOI： 10.1021/ol062378t

Biomimetic Synthesis of Acid-Sensitive (-)- and (+)-Caparrapi Oxides, (-)- and (+)-8-Epicaparrapi Oxides, and (+)-Dysifragin Induced by Artificial Cyclases 招待有り 査読有り

Muhammet Uyanik, Kazuaki Ishihara, Hisashi Yamamoto

Bioorg. Med. Chem.   13 巻 ( 17 ) 頁： 5055 - 5065   2005年5月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

Asymmetric total syntheses of acid-sensitive (-)- and (+)-caparrapi oxides (1) and (+)-8-epicaparrapi oxide (2) from farnesol (10) are achieved using Sharpless-Katsuki epoxidation and Lewis acid-assisted chiral Br?nsted acid (chiral LBA)-induced polyene cyclization as key steps. The relative configuration of (+)-dysifragin (4) is determined by a single-crystal X-ray diffraction and its total synthesis is accomplished by the diastereoselective epoxidation of (+)-1. Furthermore, (-)-1 can be directly synthesized from (S)-nerolidol (3) and (R)-LBA with 88% ds by reagent control, which overcame substrate control, while (-)-2 is obtained from (R)-3 and (R)-LBA with >99% ds by the double asymmetric induction.

DOI： 10.1016/j.bmc.2005.04.029

Biomimetic Synthesis of Acid-Sensitive (-)-Caparrapi Oxide and (+)-8-Epicaparrapi Oxide Induced by Artificial Cyclases 査読有り

Muhammet Uyanik, Hideaki Ishibashi, Kazuaki Ishihara, Hisashi Yamamoto

Organic Letters   7 巻 ( 8 ) 頁： 1601 - 1604   2005年3月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

Asymmetric total syntheses of acid-sensitive (-)-caparrapi oxide (1) and (+)-8-epicaparrapi oxide (2) from farnesol (9) were achieved using Sharpless-Katsuki epoxidation and Lewis acid-assisted chiral Brnsted acid (chiral LBA)-induced polyene cyclization as key steps. Furthermore, (-)-1 could be directly synthesized from (S)-nerolidol (3) and (R)-LBA with 88% ds by reagent control which overcame substrate control, while (-)-2 was obtained from (R)-3 and (R)-LBA with >99% ds by the double-asymmetric induction.

DOI： 10.1021/o1050295r