The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Daniel L. Comins - One of the best experts on this subject based on the ideXlab platform.
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Dihydropyridine Preparation and Application in the Synthesis of Pyridine Derivatives
Advances in Heterocyclic Chemistry, 2013Co-Authors: Daniel L. Comins, Kazuhiro Higuchi, Damian W. YoungAbstract:Abstract The preparation and application of Dihydropyridines continue to attract considerable interest in organic synthesis and medicinal chemistry. The biological activities and synthetic utility of these heterocycles have prompted the development of new routes to their construction. The Hantzsch synthesis of Dihydropyridines and pyridines has been well-studied and is now a very reliable method for preparing numerous symmetrical and asymmetrical derivatives. A widely used method to prepare 1,2- and 1,4-Dihydropyridines involves the addition of nucleophiles to N -activated pyridines. The regioselectivity of this reaction has been shown to be dependent upon the pyridine-activating reagent and the nucleophile. Numerous catalytic methods for the construction of Dihydropyridines have been developed. This review covers recent contributions to the preparation of Dihydropyridines and pyridines via acyclic and cyclic precursors, the conversion of dihydropyridine intermediates to pyridines, and the synthetic utility of Dihydropyridines as synthetic intermediates in organic synthesis.
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conversion of n acyl 2 3 dihydro 4 pyridones to 4 chloro 1 2 Dihydropyridines using the vilsmeier reagent synthesis of coniine and lupinine
Journal of Organic Chemistry, 1993Co-Authors: Rima S Alawar, Sajan P. Joseph, Daniel L. CominsAbstract:The full details are given of a study on the conversion of dihydropyridones of the type 3 to 4-chloro-1,2-Dihydropyridines 4 using a Vilsmeier reagent. The use of 1 equiv of Vilsmeier reagent under mild conditions (CICHCCl 2 , rt) transformed several racemic N-acyl-2,3-dihydro-4-pyridones 3 to Dihydropyridines 4 in very good to excellent yields (83-96%). A C-3 methyl group can be tolerated as was demonstrated in the preparation of 4-chloro-3-methyl-1,2-dihydropyridine 7 from dihydropyridone 6 in 90% yield. The utility of this conversion was demonstrated in the synthesis of the piperidine alkaloid, (-)-coniine. The synthesis of (-)-coniine was completed in five steps from 4-methoxy-3(triisopropylsilyl)pyridine in 54% overall yield. When 2,3-dihydro-4-pyridones are treated with excess Vilsmeier reagent, good yields of 4-chloro-3-formyl-1,2-Dihydropyridines result. These heterocycles are useful intermediates for alkaloid preparation, as shown by two syntheses of the quinolizidines alkaloid, (±)-lupinine, carried out in three and five steps, respectively
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Conversion of N-acyl-2,3-dihydro-4-pyridones to 4-chloro-1,2-Dihydropyridines using the Vilsmeier reagent. Synthesis of (-)-coniine and (±)-lupinine
The Journal of Organic Chemistry, 1993Co-Authors: Rima S. Al-awar, Sajan P. Joseph, Daniel L. CominsAbstract:The full details are given of a study on the conversion of dihydropyridones of the type 3 to 4-chloro-1,2-Dihydropyridines 4 using a Vilsmeier reagent. The use of 1 equiv of Vilsmeier reagent under mild conditions (CICHCCl 2 , rt) transformed several racemic N-acyl-2,3-dihydro-4-pyridones 3 to Dihydropyridines 4 in very good to excellent yields (83-96%). A C-3 methyl group can be tolerated as was demonstrated in the preparation of 4-chloro-3-methyl-1,2-dihydropyridine 7 from dihydropyridone 6 in 90% yield. The utility of this conversion was demonstrated in the synthesis of the piperidine alkaloid, (-)-coniine. The synthesis of (-)-coniine was completed in five steps from 4-methoxy-3(triisopropylsilyl)pyridine in 54% overall yield. When 2,3-dihydro-4-pyridones are treated with excess Vilsmeier reagent, good yields of 4-chloro-3-formyl-1,2-Dihydropyridines result. These heterocycles are useful intermediates for alkaloid preparation, as shown by two syntheses of the quinolizidines alkaloid, (±)-lupinine, carried out in three and five steps, respectively
Sajan P. Joseph - One of the best experts on this subject based on the ideXlab platform.
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conversion of n acyl 2 3 dihydro 4 pyridones to 4 chloro 1 2 Dihydropyridines using the vilsmeier reagent synthesis of coniine and lupinine
Journal of Organic Chemistry, 1993Co-Authors: Rima S Alawar, Sajan P. Joseph, Daniel L. CominsAbstract:The full details are given of a study on the conversion of dihydropyridones of the type 3 to 4-chloro-1,2-Dihydropyridines 4 using a Vilsmeier reagent. The use of 1 equiv of Vilsmeier reagent under mild conditions (CICHCCl 2 , rt) transformed several racemic N-acyl-2,3-dihydro-4-pyridones 3 to Dihydropyridines 4 in very good to excellent yields (83-96%). A C-3 methyl group can be tolerated as was demonstrated in the preparation of 4-chloro-3-methyl-1,2-dihydropyridine 7 from dihydropyridone 6 in 90% yield. The utility of this conversion was demonstrated in the synthesis of the piperidine alkaloid, (-)-coniine. The synthesis of (-)-coniine was completed in five steps from 4-methoxy-3(triisopropylsilyl)pyridine in 54% overall yield. When 2,3-dihydro-4-pyridones are treated with excess Vilsmeier reagent, good yields of 4-chloro-3-formyl-1,2-Dihydropyridines result. These heterocycles are useful intermediates for alkaloid preparation, as shown by two syntheses of the quinolizidines alkaloid, (±)-lupinine, carried out in three and five steps, respectively
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Conversion of N-acyl-2,3-dihydro-4-pyridones to 4-chloro-1,2-Dihydropyridines using the Vilsmeier reagent. Synthesis of (-)-coniine and (±)-lupinine
The Journal of Organic Chemistry, 1993Co-Authors: Rima S. Al-awar, Sajan P. Joseph, Daniel L. CominsAbstract:The full details are given of a study on the conversion of dihydropyridones of the type 3 to 4-chloro-1,2-Dihydropyridines 4 using a Vilsmeier reagent. The use of 1 equiv of Vilsmeier reagent under mild conditions (CICHCCl 2 , rt) transformed several racemic N-acyl-2,3-dihydro-4-pyridones 3 to Dihydropyridines 4 in very good to excellent yields (83-96%). A C-3 methyl group can be tolerated as was demonstrated in the preparation of 4-chloro-3-methyl-1,2-dihydropyridine 7 from dihydropyridone 6 in 90% yield. The utility of this conversion was demonstrated in the synthesis of the piperidine alkaloid, (-)-coniine. The synthesis of (-)-coniine was completed in five steps from 4-methoxy-3(triisopropylsilyl)pyridine in 54% overall yield. When 2,3-dihydro-4-pyridones are treated with excess Vilsmeier reagent, good yields of 4-chloro-3-formyl-1,2-Dihydropyridines result. These heterocycles are useful intermediates for alkaloid preparation, as shown by two syntheses of the quinolizidines alkaloid, (±)-lupinine, carried out in three and five steps, respectively
Rodolfo Lavilla - One of the best experts on this subject based on the ideXlab platform.
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Dihydropyridines in MCRs. Tandem processes leading to modular tetrahydroquinoline systems with up to 6 diversity elements
Molecular Diversity, 2003Co-Authors: Rodolfo Lavilla, M. Carmen Bernabeu, José Luis Díaz, Inés Carranco, Guillermo De La RosaAbstract:An efficient, modular method for the synthesis of highly substituted tetrahydroquinoline systems is described. The Lewis acid catalyzed interaction of Dihydropyridines with glyoxalate and anilines affords the heterocyclic parent systems in good yields. Tandem one-pot processes allow the incorporation of additional components: a preliminary nucleophilic attack on pyridinium salts generates the reactive dihydropyridine in situ , and subsequent electrophilic reactions on the secondary amine complete the assembly of the final targets, which have up to 6 diversity points.
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Dihydropyridine-based multicomponent reactions. Efficient entry into new tetrahydroquinoline systems through Lewis acid-catalyzed formal [4 + 2] cycloadditions.
Organic letters, 2003Co-Authors: Rodolfo Lavilla, M. Carmen Bernabeu, And Inés Carranco, José Luis DíazAbstract:The three-component reaction of Dihydropyridines, aldehydes, and p-methylaniline efficiently forms highly substituted tetrahydroquinolines in a stereoselective manner through a Lewis acid-catalyzed formal [4 + 2] cycloaddition. InCl3 and Sc(OTf)3 are the catalysts of choice for this process. The in situ generation of a reactive 1,4-dihydropyridine through the regioselective nucleophilic addition of cyanide to pyridinium salts allows a one-pot four-component transformation.
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Oxidative Diphosphonylation of 1,4-Dihydropyridines and Pyridinium Salts
Organic letters, 2000Co-Authors: Rodolfo Lavilla, Alessandro Spada, Joan BoschAbstract:An oxidative double phosphonylation of Dihydropyridines 1 and pyridinium salts 2 is achieved through the use of dialkyl phosphites, DDQ, and triethylamine. Acceptable to good yields of 2, 6-diphosphonylated-1,2-Dihydropyridines 3 are obtained in a one-pot reaction involving tandem nucleophilic addition/oxidation processes. Isomerization of 3 to the more stable 2,4-diphosphonylated-1, 4-dihydropyridine 4 was observed in some cases.
Rima S. Al-awar - One of the best experts on this subject based on the ideXlab platform.
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Conversion of N-acyl-2,3-dihydro-4-pyridones to 4-chloro-1,2-Dihydropyridines using the Vilsmeier reagent. Synthesis of (-)-coniine and (±)-lupinine
The Journal of Organic Chemistry, 1993Co-Authors: Rima S. Al-awar, Sajan P. Joseph, Daniel L. CominsAbstract:The full details are given of a study on the conversion of dihydropyridones of the type 3 to 4-chloro-1,2-Dihydropyridines 4 using a Vilsmeier reagent. The use of 1 equiv of Vilsmeier reagent under mild conditions (CICHCCl 2 , rt) transformed several racemic N-acyl-2,3-dihydro-4-pyridones 3 to Dihydropyridines 4 in very good to excellent yields (83-96%). A C-3 methyl group can be tolerated as was demonstrated in the preparation of 4-chloro-3-methyl-1,2-dihydropyridine 7 from dihydropyridone 6 in 90% yield. The utility of this conversion was demonstrated in the synthesis of the piperidine alkaloid, (-)-coniine. The synthesis of (-)-coniine was completed in five steps from 4-methoxy-3(triisopropylsilyl)pyridine in 54% overall yield. When 2,3-dihydro-4-pyridones are treated with excess Vilsmeier reagent, good yields of 4-chloro-3-formyl-1,2-Dihydropyridines result. These heterocycles are useful intermediates for alkaloid preparation, as shown by two syntheses of the quinolizidines alkaloid, (±)-lupinine, carried out in three and five steps, respectively
Rima S Alawar - One of the best experts on this subject based on the ideXlab platform.
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conversion of n acyl 2 3 dihydro 4 pyridones to 4 chloro 1 2 Dihydropyridines using the vilsmeier reagent synthesis of coniine and lupinine
Journal of Organic Chemistry, 1993Co-Authors: Rima S Alawar, Sajan P. Joseph, Daniel L. CominsAbstract:The full details are given of a study on the conversion of dihydropyridones of the type 3 to 4-chloro-1,2-Dihydropyridines 4 using a Vilsmeier reagent. The use of 1 equiv of Vilsmeier reagent under mild conditions (CICHCCl 2 , rt) transformed several racemic N-acyl-2,3-dihydro-4-pyridones 3 to Dihydropyridines 4 in very good to excellent yields (83-96%). A C-3 methyl group can be tolerated as was demonstrated in the preparation of 4-chloro-3-methyl-1,2-dihydropyridine 7 from dihydropyridone 6 in 90% yield. The utility of this conversion was demonstrated in the synthesis of the piperidine alkaloid, (-)-coniine. The synthesis of (-)-coniine was completed in five steps from 4-methoxy-3(triisopropylsilyl)pyridine in 54% overall yield. When 2,3-dihydro-4-pyridones are treated with excess Vilsmeier reagent, good yields of 4-chloro-3-formyl-1,2-Dihydropyridines result. These heterocycles are useful intermediates for alkaloid preparation, as shown by two syntheses of the quinolizidines alkaloid, (±)-lupinine, carried out in three and five steps, respectively
