- Enantioselective Halo-oxy- and Halo-azacyclizations Induced by Chiral Amidophosphate Catalysts and Halo-Lewis Acids
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Catalytic enantioselective halocyclization of 2-alkenylphenols and enamides have been achieved through the use of chiral amidophosphate catalysts and halo-Lewis acids. Density functional theory calculations suggested that the Lewis basicity of the catalyst played an important role in the reactivity and enantioselectivity. The resulting chiral halogenated chromans can be transformed to α-Tocopherol, α-Tocotrienol, Daedalin A and Englitazone in short steps. Furthermore, a halogenated product with an unsaturated side chain may provide polycyclic adducts under radical cyclization conditions.
- Lu, Yanhui,Nakatsuji, Hidefumi,Okumura, Yukimasa,Yao, Lu,Ishihara, Kazuaki
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p. 6039 - 6043
(2018/05/14)
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- New possibilities in a synthesis of (2R,4'R,8'R)-α-tocopherol (natural vitamin E)
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New methods for the synthesis of homochiral C14 and C 15-terpenoids desired as building blocks for phytilic side chain of natural α-tocopherol have been developed. A natural phytone resulted from the proposed effective method of chlo
- Spivak, Anna Yu,Shafikov, Ruslan V.,Odinokov, Victor N.
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- Enantioselective transesterification of (±)-6-benzyloxy-2,5,7,8- tetramethyl-3,4-dihydro-2H-1-benzopyran-2-ylmethanol catalyzed by the Amano PS lipase in the ionic liquid [bmim]PF6
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(S)-(-)-6-Benzyloxy-2,5,7,8-tetramethyl-3,4-dihydro-2H-1-benzopyran-2- ylmethanol, a synthon for the design of natural α-tocopherol, was obtained by kinetically selective acetylation of the corresponding racemic alcohol in the presence of the Amano PS lipase from Burkholderia cepacia in the ionic liquid 1-butyl-3-methylimidazolinium hexafluorophosphate ([bmim]PF6).
- Shafikov,Spivak, A. Yu.,Odinokov
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p. 2129 - 2132
(2011/07/30)
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- Enantioselective synthesis of (2R,4'R,8'R)-α-tocopherol (Vitamin E) based on enzymatic function
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Syntheses of (S)-chroman-2-carboxaldehyde congener 1 and (S)-chiral isoprene unit 3 were achieved based on the enzymatic acetylation of (±)- chroman-2-methanol 6 and (±)-(2,3)-anti-2-methyl-3-(p-methoxyphenyl)-1,3- propane diol 12, respectively. Synthesis of the side-chain part corresponding to (3R,7R)-3,7,11-trimethyldodecan-1-ol 27 was achieved by the coupling reaction of (S)-3 and (R)-3,7-dimethyloctyl iodide 4. The Wittig reaction of (3R,7R)-phosphonium salt 2 derived from (3R,7R)-27 and (S)-1 gave the olefin 28 which was subjected to catalytic hydrogenation to afford (2R,4'R,8'R)-α- tocopherol.
- Nozawa, Masako,Takahashi, Keiko,Kato, Keisuke,Akita, Hiroyuki
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p. 272 - 277
(2007/10/03)
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