131426-03-4Relevant articles and documents
Enantioselective synthesis of chromans for the preparation of enantiopure vitamin E and analogues
Tietze, Lutz F.,G?rlitzer, Jochen
, p. 877 - 885 (1997)
Coupling of the differently protected (hydroxymethyl)enynes 11 a-e and 12a-c with the iodoarene 7 in the presence of catalytic amounts of Pd(PPh3)4 afforded the arylenynes 5a-e and 6a-c which were transformed into the monoprotected chiral trihydroxy compounds 13 a-d and 14a,b by Sharpless bishydroxylation with >95% ee for 13 a-d, 91% ee for 14b, and 64% ee for 14a. A 5-step transformation of 13a led to the desired chroman derivative 3a which was cleaved to give the aldehyde 2 a known precursor for the enantioselective synthesis of vitamin E.
Stereoselective total synthesis method of (2R, 4 'R, 8' R)-alpha-tocopherol
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, (2022/03/02)
The invention discloses a stereoselective total synthesis method of (2R, 4 'R, 8' R)-alpha-tocopherol. The method comprises the following steps: performing iodination on trimethylhydroquinone serving as a raw material to generate aromatic halide, and performing Heck reaction and Pd/C hydrogenation on the aromatic halide and diester containing a terminal olefinic bond to form saturated aromatic diester; then diester is selectively hydrolyzed to generate monoester with high optical activity, and a chiral three-dimensional center is constructed; then carrying out methylsulfonyl chlorination and lithium aluminum hydride reduction to form a methyl-containing chiral compound; carrying out oxidation ring closing and hydrogenation reduction to construct a chiral chroman mother nucleus; then carrying out benzyl protection and Wittig reaction, and realizing carbon-carbon bond connection with C15 * fat long-chain phosphine salt; finally, double bonds are reduced to obtain (2R, 4 'R, 8' R)-alpha-tocopherol I. The method has the advantages that the raw materials are easy to obtain, the reaction condition is mild, the operation is simple and convenient, the used lipase has good stability, the catalytic form is green and environment-friendly, and the industrial application value is realized.
Highly stereoselective construction of the C2 stereocentre of α-tocopherol (Vitamin E) by asymmetric addition of Grignard reagents to ketones
Bieszczad, Bartosz,Gilheany, Declan G.
, p. 6483 - 6492 (2017/08/16)
Tertiary alcohol precursors of both C2 diastereoisomers of α-tocopherol were prepared in three ways by our recently reported asymmetric Grignard synthesis. The versatility of Grignard chemistry inherent in its three-way disconnection was exploited to allow the synthesis of three product grades: 77:23 dr (5 steps), 81:19 dr (5 steps) and 96:4 dr (7 steps, one gram scale) from readily available and abundant starting materials. The products were converted to their respective α-tocopherols in 3 steps, which allowed a definitive re-assignment of their absolute configurations.
Enantioselective synthesis of the chromane moiety of vitamin E
Tietze, Lutz F.,Goerlitzer, Jochen,Schuffenhauer, Ansgar,Huebner, Matthias
, p. 1075 - 1084 (2007/10/03)
Several new approaches for the enantioselective synthesis of the chromane moiety of vitamin E are described. Sonogashira coupling of 3a with the alkyne 4 and subsequent elimination gave 6, which was bis(hydroxylated) in 93% yield and with 85% ee. Recrystallization gave enantiopure 7a, which was hydrogenated and transformed into the vitamin E precursor 11. The bis(hydroxylation) of 18 and 21 to give 9 and 22, respectively, was less than satisfactory, proceeding with ee values of 28% and 18%. In contrast, stereoselective allylation of ketone 15 followed by removal of the protecting group or ozonolysis of the allyl moiety furnished the allyl alcohol 26 and the aldehyde 27, respectively, in almost enantiopure form, which again could be used as precursors for vitamin E. Partial hydrogenation of 5a gave the alkene 32a and that of 28 the alkene 30b, both of which show interesting atropisomerism.
