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Scott D. Rychnovsky - One of the best experts on this subject based on the ideXlab platform.
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Silyl Enol Ether Prins Cyclization: Diastereoselective Formation of Substituted Tetrahydropyran-4-ones
2016Co-Authors: Gidget C. Tay, Chloe Y Huang, Scott D. RychnovskyAbstract:ABSTRACT: A diastereoselective synthesis of cis-2,6-disubstituted Tetrahydropyran-4-ones was developed. The key step of this methodology, a silyl enol ether Prins cyclization, was promoted by a condensation reaction between a hydroxy silyl enol ether and an aldehyde to afford substituted Tetrahydropyran-4-ones. The cyclization was tolerant of many functional groups, and the modular synthesis of the hydroxy silyl enol ether allowed for the formation of more than 30 new Tetrahydropyran-4-ones with up to 97 % yield and>95:5 dr. The cyclization step forms new carbon−carbon and carbon−oxygen bonds, as well as a quaternary center with good diastereoselectivity. The method provides a versatile route for the synthesis of substituted Tetrahydropyrans. Substituted Tetrahydropyrans and Tetrahydropyranones are a common motif in numerous biologically active natural products (Figure 1).1 Synthesis of Tetrahydropyran-4-ones (THPOs), followed by reduction of the ketone, has been used to form 4
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Symmetric Macrocycles by a Prins Dimerization and Macrocyclization Strategy
2015Co-Authors: Michael R. Gesinski, Kwanruthai Tadpetch, Scott D. RychnovskyAbstract:A tandem dimerization/macrocyclization reaction utilizing the Prins cyclization has been developed. This reaction develops molecular complexity through the formation of highly substituted dimeric Tetrahydropyran macrocycles. Mild conditions utilizing rhenium(VII) catalysts were explored for aromatic substrates while harsher Lewis acidic conditions were used for aliphatic substrates. Both aldehydes and acetals are shown to be viable substrates for this reaction. Oxacyclic macrodimers are an important class of natural products that offer a wide array of structural complexity and bioactivity.1 These macrolides have become popular targets for synthetic chemists.2 The most direct way to construct these molecules is through the union of two monomeric species in a tandem dimerization and macrocyclization reaction. The most common version of this strategy utilizes two esterification reactions between an activated acid and an alcohol, the initial dimerization followed by a macrolactonization.3 While often successful, this approach does not greatly enhance the complexity of the intermediate through the formation of carbon-carbon bonds. Alternative bond-forming reactions, such as Suzuki coupling and olefin metathesis have been used with occasional success in dimerization and macrocyclization strategies.4,5 Herein we describe a new dimerization and macrocyclization strategy based on the Prins cyclization reaction. The Prins cyclization is a powerful reaction that forms cis-2,6-disubstituted Tetrahydropyrans (THPs) through the addition of an olefin to an oxocarbenium ion generated from the condensation of an aldehyde with a homoallylic alcohol.6 Recently, intramolecular Prins cyclizations have been utilized as key macrocyclization steps in the synthesis of several THP containing natural products (Figure 1 A).7 We report the extension of this methodology to the formation of oxacyclic macrodimers through sequential Prins dimerization and macrocyclization reactions (Figure 1 B). This synthetic strategy has been applied to a model for the marine macrodiolide clavosolide A
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Silyl Enol Ether Prins Cyclization: Diastereoselective Formation of Substituted Tetrahydropyran-4-ones
2015Co-Authors: Gidget C. Tay, Chloe Y Huang, Scott D. RychnovskyAbstract:A diastereoselective synthesis of cis-2,6-disubstituted Tetrahydropyran-4-ones was developed. The key step of this methodology, a silyl enol ether Prins cyclization, was promoted by a condensation reaction between a hydroxy silyl enol ether and an aldehyde to afford substituted Tetrahydropyran-4-ones. The cyclization was tolerant of many functional groups, and the modular synthesis of the hydroxy silyl enol ether allowed for the formation of more than 30 new Tetrahydropyran-4-ones with up to 97% yield and >95:5 dr. The cyclization step forms new carbon–carbon and carbon–oxygen bonds, as well as a quaternary center with good diastereoselectivity. The method provides a versatile route for the synthesis of substituted Tetrahydropyrans
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silyl enol ether prins cyclization diastereoselective formation of substituted Tetrahydropyran 4 ones
Journal of Organic Chemistry, 2014Co-Authors: Chloe Y Huang, Scott D. RychnovskyAbstract:A diastereoselective synthesis of cis-2,6-disubstituted Tetrahydropyran-4-ones was developed. The key step of this methodology, a silyl enol ether Prins cyclization, was promoted by a condensation reaction between a hydroxy silyl enol ether and an aldehyde to afford substituted Tetrahydropyran-4-ones. The cyclization was tolerant of many functional groups, and the modular synthesis of the hydroxy silyl enol ether allowed for the formation of more than 30 new Tetrahydropyran-4-ones with up to 97% yield and >95:5 dr. The cyclization step forms new carbon–carbon and carbon–oxygen bonds, as well as a quaternary center with good diastereoselectivity. The method provides a versatile route for the synthesis of substituted Tetrahydropyrans.
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Solvolysis of a Tetrahydropyranyl mesylate: mechanistic implications for the Prins cyclization, 2-oxonia-cope rearrangement, and Grob fragmentation.
Organic letters, 2006Co-Authors: Ramesh Jasti, Scott D. RychnovskyAbstract:A solvolysis reaction is used to demonstrate that a Tetrahydropyranyl cation is a common intermediate for Prins cyclizations, 2-oxonia Cope rearrangements, and Grob fragmentations of Tetrahydropyran rings.
Chloe Y Huang - One of the best experts on this subject based on the ideXlab platform.
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Silyl Enol Ether Prins Cyclization: Diastereoselective Formation of Substituted Tetrahydropyran-4-ones
2016Co-Authors: Gidget C. Tay, Chloe Y Huang, Scott D. RychnovskyAbstract:ABSTRACT: A diastereoselective synthesis of cis-2,6-disubstituted Tetrahydropyran-4-ones was developed. The key step of this methodology, a silyl enol ether Prins cyclization, was promoted by a condensation reaction between a hydroxy silyl enol ether and an aldehyde to afford substituted Tetrahydropyran-4-ones. The cyclization was tolerant of many functional groups, and the modular synthesis of the hydroxy silyl enol ether allowed for the formation of more than 30 new Tetrahydropyran-4-ones with up to 97 % yield and>95:5 dr. The cyclization step forms new carbon−carbon and carbon−oxygen bonds, as well as a quaternary center with good diastereoselectivity. The method provides a versatile route for the synthesis of substituted Tetrahydropyrans. Substituted Tetrahydropyrans and Tetrahydropyranones are a common motif in numerous biologically active natural products (Figure 1).1 Synthesis of Tetrahydropyran-4-ones (THPOs), followed by reduction of the ketone, has been used to form 4
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Silyl Enol Ether Prins Cyclization: Diastereoselective Formation of Substituted Tetrahydropyran-4-ones
2015Co-Authors: Gidget C. Tay, Chloe Y Huang, Scott D. RychnovskyAbstract:A diastereoselective synthesis of cis-2,6-disubstituted Tetrahydropyran-4-ones was developed. The key step of this methodology, a silyl enol ether Prins cyclization, was promoted by a condensation reaction between a hydroxy silyl enol ether and an aldehyde to afford substituted Tetrahydropyran-4-ones. The cyclization was tolerant of many functional groups, and the modular synthesis of the hydroxy silyl enol ether allowed for the formation of more than 30 new Tetrahydropyran-4-ones with up to 97% yield and >95:5 dr. The cyclization step forms new carbon–carbon and carbon–oxygen bonds, as well as a quaternary center with good diastereoselectivity. The method provides a versatile route for the synthesis of substituted Tetrahydropyrans
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silyl enol ether prins cyclization diastereoselective formation of substituted Tetrahydropyran 4 ones
Journal of Organic Chemistry, 2014Co-Authors: Chloe Y Huang, Scott D. RychnovskyAbstract:A diastereoselective synthesis of cis-2,6-disubstituted Tetrahydropyran-4-ones was developed. The key step of this methodology, a silyl enol ether Prins cyclization, was promoted by a condensation reaction between a hydroxy silyl enol ether and an aldehyde to afford substituted Tetrahydropyran-4-ones. The cyclization was tolerant of many functional groups, and the modular synthesis of the hydroxy silyl enol ether allowed for the formation of more than 30 new Tetrahydropyran-4-ones with up to 97% yield and >95:5 dr. The cyclization step forms new carbon–carbon and carbon–oxygen bonds, as well as a quaternary center with good diastereoselectivity. The method provides a versatile route for the synthesis of substituted Tetrahydropyrans.
J S Yadav - One of the best experts on this subject based on the ideXlab platform.
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synthesis of the spiroketal fragment of ushikulide a
ChemInform, 2015Co-Authors: J S Yadav, Mallikarjuna N Reddy, Md Ataur Rahman, A R PrasadAbstract:The synthesis of the title fragment (I) involves the use of TosMIC as alkylating reagent and a Prins cyclization to construct the functionalized Tetrahydropyran ring.
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formation of substituted Tetrahydropyrans through oxetane ring opening application to the synthesis of c1 c17 fragment of salinomycin
Organic Letters, 2014Co-Authors: J S Yadav, Vinay K Singh, P SrihariAbstract:The stereoselective synthesis of C1–C17 fragment of salinomycin is achieved. The strategy employs a desymmetrization approach and utilizes an intramolecular oxetane opening reaction with O-nucleophile to result in the Tetrahydropyran skeleton as the key step.
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thermodynamic investigations of ternary o toluidine Tetrahydropyran n n dimethylformamide mixture and its binaries at 298 15 303 15 and 308 15 k
Journal of Molecular Liquids, 2011Co-Authors: Sunil K Jangra, J S Yadav, V K SharmaAbstract:Abstract The densities ρ, speed of sound u, data of o-toluidine (i) + Tetrahydropyran (j) + N,N-dimethylformamide (k) and its {Tetrahydropyran (j) + N,N-dimethylformamide (k); o-toluidine (i) + N,N-dimethylformamide (k)} binaries have been measured as a function of composition at 298.15, 303.15 and 308.15 K. The excess molar enthalpies, HE data of same set of binary mixtures have also been measured over entire composition at 308.15 K. The densities and speeds of sound data of binary and ternary mixtures have been utilized to determine their excess molar volumes, VE and excess isentropic compressibilities, κSE. The observed thermodynamic properties of binary and ternary mixtures have been analyzed in terms of Graph theory. It has been observed that Graph theory correctly predicts the sign as well as magnitude of thermodynamic properties.
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a novel prins alkynylation reaction for the synthesis of 4 phenacyl Tetrahydropyrans
Tetrahedron Letters, 2010Co-Authors: J S Yadav, B Subba V Reddy, Jayasudhan Y Reddy, Bh Phaneendra Reddy, Adi Narayana P ReddyAbstract:Abstract Aldehyde, homoallylic alcohol, and alkyne undergo smooth Prins-type cyclization in the presence of BF 3 ·OEt 2 /CuCl (10 mol % each) in dichloromethane under mild reaction conditions to afford 4-phenacyl Tetrahydropyran derivatives in good yields. This method is highly stereoselective, affording cis -Tetrahydropyrans exclusively. The salient features of this method are high conversions, mild reaction conditions, short reaction times, high selectivity, and operational simplicity.
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cecl3 7h2o accl catalyzed prins ritter reaction sequence a novel synthesis of 4 amido Tetrahydropyran derivatives
Tetrahedron Letters, 2007Co-Authors: J S Yadav, B Subba V Reddy, G Narayana G K S Kumar, Madhusudhan G ReddyAbstract:Homoallylic alcohols, carbonyl compounds and nitriles undergo a smooth tandem Prins–Ritter type cyclization in the presence of CeCl3·7H2O/AcCl at ambient temperature to produce 4-amido Tetrahydropyrans in high yields with all cis-selectivity. Spirocyclic 4-amido Tetrahydropyrans are obtained in the case of cyclic ketones.
Lauri Vares - One of the best experts on this subject based on the ideXlab platform.
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an efficient and highly stereoselective approach to trans 2 5 disubstituted tetrahydrofuran and trans 2 6 disubstituted Tetrahydropyran derivatives
Tetrahedron Letters, 2014Co-Authors: Indrek Veidenberg, Lauri Toom, Piret Villo, Lauri VaresAbstract:Abstract Bis-epoxides were converted into trans -2,5-disubstituted-tetrahydrofuran and trans -2,6-disubstituted-Tetrahydropyran derivatives using a kinetic resolution followed by cyclization, in an efficient and highly enantio- and diastereoselective manner.
K. N. Houk - One of the best experts on this subject based on the ideXlab platform.
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Mechanism of the Manolikakes Enamide-Based Domino Reaction for the Stereospecific Construction of Tetrahydropyrans.
The Journal of organic chemistry, 2020Co-Authors: Shuming Chen, Jonathan J. Wong, K. N. HoukAbstract:The mechanism and stereoselectivity of the BF3-catalyzed, enamide-based domino reaction developed by Manolikakes et al. for Tetrahydropyran synthesis have been studied using density functional theo...
