- A dihydro maltol and dihydro ethyl maltol synthetic method
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The invention discloses a dihydro maltol and dihydro ethyl maltol synthesis method. The method includes A, according to a formula II, allowing 2-methyl-5, 6-dihydro-2H-pyran and hydrogen peroxide to perform dihydroxylation under the effect of strong acid ion exchange resin, and obtaining a 2-methyl-3 and 4-dihydro-tetrahydropyrane intermediates of a formula III; B, according to the formula III, oxidizing the 2-methyl-3 and 4-dihydro-tetrahydropyrane intermediates through oxidation agent, and obtaining a compound of a formula IV. When R = ethyl, the compound of the formula IV is dihydro ethyl maltol; when R = methyl, the compound of the formula IV is dihydro maltol. The method adopts conventional chemical raw materials, and the reaction condition is mild.
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Paragraph 0021; 0022; 0023
(2017/08/25)
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- Catalytic asymmetric [4+2]-cycloaddition of dienes with aldehydes
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Despite its significant potential, a general catalytic asymmetric [4+2]-cycloaddition of simple and electronically unbiased dienes with any type of aldehyde has long been unknown. Previously developed methodologies invariably require activated, electronically engineered substrates. We now provide a general solution to this problem. We show that highly acidic and confined imidodiphosphorimidates (IDPis) are extremely effective Br?nsted acid catalysts of the hetero-Diels-Alder reaction of a wide variety of aldehydes and dienes to give enantiomerically enriched dihydropyrans. Excellent stereoselectivity is generally observed and a variety of scents and natural products can be easily accessed.
- Liu, Luping,Kim, Hyejin,Xie, Youwei,Fares, Christophe,Kaib, Philip S.J.,Goddard, Richard,List, Benjamin
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supporting information
p. 13656 - 13659
(2017/11/06)
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- Regioselective Ni(II)-assisted alkylation of 2-methoxy-5,6- dihydro-2H-pyran: A new route to 2-n.alkyl-5,6-dihydro-2H-pyrans
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In the presence of a catalytic amount of NidppeCl2, 2-methoxy- 5,6-dihydro-2H-pyran reacts with primary Grignard reagents to give the corresponding 2-n.alkyl-5,6-dihydro-2H-pyrans in satisfactory yields.
- Guagnano, Vito,Lardicci, Luciano,Malanga, Corrado,Menicagli, Rita
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p. 2025 - 2026
(2007/10/03)
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