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Berberine and coptisine free bases
Abstract The free bases of protoberberine alkaloids berberine and coptisine and related compounds have been examined. The 1H and 13C NMR data of 8-hydroxy-7,8-dihydroberberine (2a),Expand
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Synthesis of the anti-HIV agent (-)-hyperolactone C by using oxonium ylide formation-rearrangement.
Starting from readily available (S)-styrene oxide an asymmetric synthesis is described of the naturally occurring anti-HIV spirolactone (-)-hyperolactone C, which possesses adjacent fully substitutedExpand
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Fused Tetracyclic Heterocycles by Thermally Initiated Intramolecular Criss-Cross Cycloaddition of 3-Substituted Homoallenylaldazines
A thermally initiated intramolecular criss-cross cycloaddition of 3-substituted symmetrical homoallenyl azines (5) was searched. Their cyclization led to interesting new fused heterocyclic systemsExpand
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Molecular and Crystal Structures of Three Berberine Derivatives
Berberine azide, berberine thiocyanate, and 8-cyano-8H-berberine were prepared from berberine chloride, a quaternary protoberberine alkaloid. The molecular and crystal structures of all compounds areExpand
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Rearrangement of fused tetracyclic heterocycles induced by alkyl halides and formation of a new type of ‘proton sponge’
Abstract Intramolecular criss-cross cycloaddition of 3-substituted symmetrical homoallenyl azines 2 by heating in xylene lead to interesting fused heterocyclic systems consisting of fourExpand
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The Synthesis of Two Regioisomeric Aldehydes with a Tetrahydrobenzo[b]thiophene Scaffold and Their Application in Solvent-Free Intramolecular 1,3-Dipolar Cycloaddition Reactions
The paper describes the synthesis of two regioisomeric 2-amino-3-formyl- and 3-amino-2-formyl-substituted derivatives of tetrahydrobenzo[ b ]thiophene and their subsequent thermally initiatedExpand
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A new and facile synthesis of methyl 3-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-2-carboxylate
A four-step synthesis of methyl 3-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-2-carboxylate from commercially available starting materials is presented.
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Unexpected Heterocyclic Products from Cycloaddition Reactions of Nonsymmetrical Allenyl Aldoketazines with Substituted Alkynes
Thermally initiated cycloaddition reactions of nonsymmetrical allenyl azines 1 with alkynes or other dipolarophiles usually lead to compounds with three fused, five-membered heterocyclic rings. WithExpand
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Dihydropyrrolo[1,2-b]pyrazoles: withasomnine and related compounds
In the paper we indicate the increasing importance of derivatives containing a dihydropyrrolo[1,2-b]pyrazole (DPP) core. We try to show our synthetic approach based on an improved Kulinkovich methodExpand
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Cyclization of β-allenyloximes as a novel method for nitrone preparation
Two different procedures for β-allenyloxime cyclization are described. One leads to substituted 1-hydroxypyrrolidines and the other represents a new route to pyrroline-N-oxides.
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