621-06-7Relevant articles and documents
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Watanabe et al.
, p. 1869 (1979)
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Photocatalyzed Triplet Sensitization of Oximes Using Visible Light Provides a Route to Nonclassical Beckmann Rearrangement Products
Zhang, Xiao,Rovis, Tomislav
, p. 21211 - 21217 (2021/12/27)
Oximes are valuable synthetic intermediates for the preparation of a variety of functional groups. To date, the stereoselective synthesis of oximes remains a major challenge, as most current synthetic methods either provide mixtures of E and Z isomers or furnish the thermodynamically preferred E isomer. Herein we report a mild and general method to achieve Z isomers of aryl oximes by photoisomerization of oximes via visible-light-mediated energy transfer (EnT) catalysis. Facile access to (Z)-oximes provides opportunities to achieve regio- and chemoselectivity complementary to those of widely used transformations employing oxime starting materials. We show an enhanced one-pot protocol for photocatalyzed oxime isomerization and subsequent Beckmann rearrangement that enables novel reactivity with alkyl groups migrating preferentially over aryl groups, reversing the regioselectivity of the traditional Beckmann reaction. Chemodivergent N- or O- cyclizations of alkenyl oximes are also demonstrated, leading to nitrones or cyclic oxime ethers, respectively.
Alpha-carbonyl alkenyl ester compound as well as preparation method and application thereof
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Paragraph 0492-0497, (2021/08/25)
The invention provides an alpha-carbonyl alkenyl ester compound and a preparation method thereof. The alpha-carbonyl alkenyl ester compound is also used for reacting with primary or secondary amine to prepare an amide compound. Two steps of reactions are combined to develop an amido bond and peptide bond forming method which takes carboxylic acid and amine as starting raw materials and allene ketone as a condensing agent. Meanwhile, the alpha-carbonyl alkenyl ester compound of the alpha-amino acid is used as a polypeptide synthesis building block for solid-phase synthesis of polypeptide. The method is mild in reaction condition, simple to operate and high in yield. Compared with an existing amido bond condensation reagent, allene ketone has the advantages of being easy and convenient to prepare, good in stability, small in molecular weight and free of racemization when alpha-chiral carboxylic acid is activated and the like. The compound is a novel amido bond and peptide bond condensation reagent.
