53713-36-3Relevant articles and documents
Enantioselective Halo-oxy- and Halo-azacyclizations Induced by Chiral Amidophosphate Catalysts and Halo-Lewis Acids
Lu, Yanhui,Nakatsuji, Hidefumi,Okumura, Yukimasa,Yao, Lu,Ishihara, Kazuaki
supporting information, p. 6039 - 6043 (2018/05/14)
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.
Enantioselective palladium-catalyzed total synthesis of vitamin E by employing a domino Wacker-Heck reaction
Tietze, Lutz F.,Stecker, Florian,Zinngrebe, Julia,Sommer, Konrad M.
, p. 8770 - 8776 (2007/10/03)
An enantioselective total synthesis of vitamin E in which a novel palladium-catalyzed domino reaction was employed as the key step is described. This reaction allows the formation of the chiral chroman framework and the concurrent introduction of part of the side chain of vitamin E. The sequence comprises an enantioselective Wacker cyclization and a subsequent Heck reaction. Accordingly, reaction of alkenylphenol 12 with methyl vinyl ketone (13) in the presence of catalytic amounts of Pd(OTFA)2 (TFA = trifluoroacetate), the enantiopure ligand (S,S)-Bn-BOXAX (8b; Bn = benzyl, BOXAX = 2,2′-bis(oxazolyl)-1,1′-binaphthyl, and p-benzoquinone (9) as an oxidant gives access to chiral chroman 10 with an enantioselectivity of 97% ee in 84% yield. Chroman 10 is then converted into 24 by an aldol condensation reaction with (3R)-3,7-dimethyloctanal (11). Subsequent 1,2-addition of methyllithium, elimination of water, and hydrogenation yields vitamin E.
Antioxidant chroman compounds
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, (2008/06/13)
The (6-hydroxy-chroman-2-yl) acetic or carboxylic acid derivatives useful as antioxidants and a method for preparing these derivatives from hydroquinones and intermediates in this synthesis as well as the use of these derivatives as intermediates in the preparation of optically active alpha-tocopherol.
