- Enzymatic Preparation of Chiral 4-Hydroxy-2,2-dimethyl-1-cyclohexanone as a Chiral Building Block
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(S)-4-Hydroxy-2,2-dimethyl-1-cyclohexanone (1a) was prepared by two enzymatic methods. 1,4-Cyclohexanediol was converted to monoacetal (11) via (+/-)-1a.Enzymatic reduction of 11 by baker's yeast gave (S)-1 of almost 100 percent e.e.Direct hydroxylation of 2,2-dimethyl-1-cyclohexanone (14) by P-450 camphor monooxygenase of the cloned genes of Pseudomonas putida PpG1 gave (S)-1a of almost 100 percent e.e., too.According to Mitsunobu's method, SN-2 inversion of (S)-1 gave (R)-1.
- Yamamoto, Hiroshi,Oritani, Takayuki,Koga, Hideo,Horiuchi, Tadao,Yamashita, Kyohei
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p. 1915 - 1921
(2007/10/02)
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- Syntheses of Chiral 4'-Hydroxy and 1',4'-Dihydroxy-γ-ionylideneacetic Acids, Fungal Biosynthetic Intermediates of Abscisic Acid
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Both chiral 4'-hydroxy and 1',4'-dihydroxy-γ-ionylideneacetic acids (3, 4 and 5), biosynthetic intermediates of abscisic acid produced by Cercospora cruenta, were synthesized from a chiral starting material, (R)- or (S)-4-hydroxy-2,2-dimethyl-1-cyclohexanone (7). -Sigmatropic rearrangement of (S)-1-chloromethyl-3,3-dimethyl-5-tetrahydropyranyl(THP)oxy-1-cyclohexene (8), followed by the Reformatsky reaction with 4-bromo-3-methyl-2-butenoate (10) gave (1'R,4'S)-4.The diastereomeric isomer, (1'R,4'R)-3, was synthesized in the same manner.The reaction of (S)-2,2-dimethyl-5-methylene-4-THPoxy-1-cyclohexanone (14) with a Grignard reagent prepared from (Z)-3-methyl-2-penten-4-ynyl THP ether (15) and subsequent conversion of the side chain gave (1'S,4'S)-5.These synthetic compounds confirmed the stereochemistry of natural 3, 4 and 5.
- Yamamoto, Hiroshi,Oritani, Takayuki,Yamashita, Kyohei
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p. 1923 - 1929
(2007/10/02)
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