- Benzotriazole: A novel synthetic auxiliary
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Benzotriazole and aldehydes react reversibly to give addition products: in the presence of amines and other NH-compounds water can be eliminated to form products of type Bt-CHR-NR′R″. The latter are versatile intermediates for the preparation of primary, secondary, and tertiary amines and in the alkylation of hydroxylamines, hydrazines, amides, thioamides, and sulfonamides. Polyfunctional amines and other polyfunctional compounds can also be prepared, and they enable significant extending of Mannich reaction. Similar oxygen compounds Bt-CRR′-OR″ enable new syntheses of ethers and esters. Reactions in which benzotriazole is eliminated rather than substituted open up new pathways to enamines, enol ethers, and nitrones. The methodology is capable of extension to a variety of vinylogous systems including benzenoid and heteroaromatic derivatives. In addition to acting as a versatile leaving group, benzotriazolyl residues activate neighboring CH bonds to proton loss and a variety of such applications is described.
- Katritzky, Alan R.,Rachwal, Stanislaw,Hitchings, Gregory J.
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p. 2683 - 2732
(2007/10/02)
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- A Novel and Versatile Synthesis of 1-Alkyl-, 1-Aryl-, 1-(Alkylamino)-, or 1-Amido-Substituted and of 1,2,6-Trisubstituted Piperidines from Glutaraldehyde and Primary Amines or Monosubstituted Hydrazines
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Various primary amines and 1-mono- and 1,1-disubstituted hydrazines were converted into the corresponding N-substituted piperidines in good to excellent yields via the products of double condensations with benzotriazole and glutaraldehyde.Reduction of the 2,6-bis(benzotriazolyl) N-substituted piperidines 4 and 7 with sodium borohydride in tetrahydrofuran afforded N-substituted piperidines.The benzotriazole moieties were also replaced by alkyl groups by reaction with Grignard reagents to produce 1,2,6-trisubstituted piperidines.
- Katritzky, Alan R.,Fan, Wei-Qiang
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p. 3205 - 3209
(2007/10/02)
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