- Photocatalyzed Triplet Sensitization of Oximes Using Visible Light Provides a Route to Nonclassical Beckmann Rearrangement Products
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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.
- Zhang, Xiao,Rovis, Tomislav
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p. 21211 - 21217
(2021/12/27)
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- 2,2-Diazido-1,2-diarylethanones: Synthesis and Reactivity with Primary Amines
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We describe the synthesis and reactivity of a new class of diazidated compounds: the 2,2-diazido-1,2-diarylethanones. The diazides are easily accessible from 1,2-diarylethanones through a mild and simple protocol for the direct oxidative diazidation, using iodine and sodium azide in DMSO at room temperature. In studies towards their reactivity with amine nucleophiles under basic conditions, the diazides are shown to undergo a controlled fragmentation reaction that provides a straightforward access to the corresponding amides. In stark contrast to our previous results on the amine-triggered fragmentation of diazidated compounds, aromatic nitriles are found to be by-products of synthetic value. The net reaction consisting of diazidation and subsequent fragmentation, thus, provides a simple way to convert 1,2-diarylethanones into both aromatic amides and nitriles.
- Holzschneider, Kristina,H?ring, Andreas P.,Kirsch, Stefan F.
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p. 2824 - 2831
(2019/04/30)
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- Co2(CO)8 as a convenient in situ CO source for the direct synthesis of benzamides from aryl halides (Br/I) via aminocarbonylation
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A fast, mild, and functional group tolerant method for the direct synthesis of benzamides from aryl halides (Br, I) via aminocarbonylation, using solid Co2(CO)8 as a convenient CO source, has been demonstrated. The developed method is applicable to a wide variety of 1° and cyclic and acyclic 2°amines. Nitro substituted (o, m and p) aryl halides have easily been converted to the corresponding benzamides, without the reduction of the nitro group, in high yields using this in situ carbonylation methodology under microwave irradiation.
- Baburajan, Poongavanam,Elango, Kuppanagounder P.
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supporting information
p. 1006 - 1010
(2015/02/19)
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- Co2(CO)8 as a convenient in situ CO source for the direct synthesis of benzamides from aryl halides (Br/I) via aminocarbonylation
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A fast, mild, and functional group tolerant method for the direct synthesis of benzamides from aryl halides (Br, I) via aminocarbonylation, using solid Co2(CO)8 as a convenient CO source, has been demonstrated. The developed method is applicable to a wide variety of 1 and cyclic and acyclic 2 amines. Nitro substituted (o, m and p) aryl halides have easily been converted to the corresponding benzamides, without the reduction of the nitro group, in high yields using this in situ carbonylation methodology under microwave irradiation.
- Baburajan, Poongavanam,Elango, Kuppanagounder P.
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supporting information
p. 1006 - 1010
(2014/02/14)
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- The First ZnII-Catalyzed Oxidative Amidation of Benzyl Alcohols with Amines under Solvent-Free Conditions
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The first zinc-catalyzed oxidative amidation of benzyl alcohols has been developed. Both aliphatic and aromatic amines can be tolerated and applied in this reaction. Various amides were prepared in good yields under solvent-free and mild conditions. Copyright
- Wu, Xiao-Feng,Sharif, Muhammad,Pews-Davtyan, Anahit,Langer, Peter,Ayub, Khurshid,Beller, Matthias
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supporting information
p. 2783 - 2787
(2013/06/26)
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- Esters and amides from activated alcohols using manganese(IV) dioxide: Tandem oxidation processes
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Manganese(IV) dioxide can be used in conjunction with sodium cyanide in THF-methanol or in methanol alone for the direct conversion of activated alcohols into methyl esters. Ethyl and isopropyl esters can also be prepared. Similarly, use of manganese(IV) dioxide and sodium cyanide in THF containing ammonia or primary amines can be used to convert alcohols into the corresponding amides. Several activated alcohols and one non-activated alcohol example are reported.
- Foot, Jonathan S.,Kanno, Hisashi,Giblin, Gerard M. P.,Taylor, Richard J. K.
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p. 1055 - 1064
(2007/10/03)
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- Tandem oxidation processes: The direct conversion of activated alcohols into esters and amides
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The direct conversion of primary alcohols into methyl esters and amides using manganese dioxide and sodium cyanide with methanol or the appropriate amine is reported. These transformations, which proceed via an in situ four step, double oxidation sequence, have been applied to a range of benzylic, heterocyclic, allylic and propargylic alcohols.
- Foot, Jonathan S.,Kanno, Hisashi,Giblin, Gerard M. P.,Taylor, Richard J. K.
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p. 1293 - 1295
(2007/10/03)
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- In Situ Oxidation-Imine Formation-Reduction Routes from Alcohols to Amines
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(matrix presented) Manganese dioxide is employed as an in situ oxidant for the one-pot conversion of alcohols into imines. In combination with polymer-supported cyanoborohydride (PSCBH), a one-pot oxidation-imine formation-reduction sequence is reported. This procedure enables alcohols to be converted directly into both secondary and tertiary amines.
- Blackburn, Leonie,Taylor, Richard J. K.
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p. 1637 - 1639
(2007/10/03)
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- Potential Central Nervous System Active Agents. 4. Synthesis of N-Isobutylbenzamides
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The preparation and spectral properties (IR, 1HNMR) are given for 11 N-isobutylbenzamides, variously substituted on the acyl part with halo, methoxyl, methyl, or nitro groups, including two new ones.The amides were synthesized by the Schotten-Baumann meth
- Agwada, Vincent C.,Beak, Peter
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p. 235 - 237
(2007/10/02)
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