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US 8,912,345 B2Granted
Method for preparing optically pure (−)-clausenamide compound
AssigneeInstitute of Chemistry, Chinese Academy of Sciences
InventorsYian Shi, Xianyou Peng, Peijun Li
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Abstract
Disclosed in the present invention is a method for preparing a (−)-clausenamide compound of formula (I), comprising: firstly, catalyzing the asymmetrical epoxidation of trans-cinnamate using a chiral ketone derived from fructose or a hydrate thereof as a catalyst, and then subjecting the product to amidation, oxidation, cyclization and reduction successively to finally obtain the optically pure (−)-clausenamide compound of formula (I).
Claims10
A method for preparing a (−)-clausenamide compound represented by formula (I), comprising the following steps:
- (1) in the presence of an oxidant and a catalyst, trans-cinnamate represented by formula (II) is converted to (2S,3R)-epoxy cinnamate represented by formula (III) through asymmetric epoxidation reaction;
- the catalyst is fructose-derived chiral ketone represented by formula (IV) or a hydrate of fructose-derived chiral ketone represented by formula (V);
- wherein, both R1 and R2 are any one selected from the group consisting of phenyl, o-methoxyphenyl, m-methoxyphenyl, p-methoxyphenyl, o-methylphenyl, m-methylphenyl, p-methylphenyl, p-fluorophenyl, p-chlorophenyl, p-bromophenyl, o-fluorophenyl, o-chlorophenyl, o-bromophenyl, 3,4,5-trimethoxyphenyl, p-nitrophenyl, and α-naphthyl;
- R3 is any one selected from the group consisting of hydrogen, methyl, benzyl, p-methoxybenzyl, and hydroxymethyl;
- R4 is any one selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, cyclohexyl, and benzyl;
- and Ac is acetyl;
- (2) in the presence of an alkaline compound, amidation reaction takes place between (2S,3R)-epoxy cinnamate represented by formula (III) and a compound represented by formula (VI), to obtain a compound represented by formula (VII);
- wherein, the definitions of R1, R2 and R3 are the same as those in formula (I);
- (3) in the presence of ruthenium trichloride and the oxidant, the compound represented by formula (VII) is converted to a compound represented by formula (VIII) through oxidation reaction;
- wherein, the definitions of R1, R2 and R3 are the same as those in formula (I);
- (4) in the presence of an alkaline compound, the compound represented by formula (VIII) is converted to (−)-clausenamidone represented by formula (IX) through cyclization reaction;
- wherein, the definitions of R1, R2 and R3 are the same as those in formula (I);
- (5) the (−)-clausenamidone represented by formula (IX) is converted to the (−)-clausenamide represented by the formula (I) through reduction reaction.
10 more elements
Dependencies are inferred from the claim text.