The Experts below are selected from a list of 90 Experts worldwide ranked by ideXlab platform
Robert A. Batey - One of the best experts on this subject based on the ideXlab platform.
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Organoboron-Based Allylation Approach to the Total Synthesis of the Medium-Ring Dilactone (+)-Antimycin A1b
The Journal of organic chemistry, 2014Co-Authors: John Janetzko, Robert A. BateyAbstract:The stereoselective synthesis of (+)-antimycin A1b has been accomplished in 12 linear steps and 18% overall yield from (−)-ethyl lactate. A robust, scalable, and highly diastereoselective montmorillonite K10-promoted allylation reaction between an α-silyloxy aldehyde and a substituted potassium allyltrifluoroborate salt provides a general approach to the core stereochemical triad of the antimycin A family. The requisite (Z)-substituted potassium allyltrifluoroborate salt was synthesized using a syn-selective hydroboration/protodeboration of an alkynylboronate ester, followed by a Matteson Homologation reaction. The total synthesis leverages an MNBA (Shiina’s reagent)-mediated macrolactonization to generate the 9-membered dilactone ring and a late-stage PyBOP-mediated amide coupling employing an unprotected 3-formamidosalicylic acid fragment, thereby shortening the longest linear sequence and, perhaps most notably, generating the antimycin A C7–C8–C9 stereotriad in a single step using a single chiral pool-...
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Organoboron-Based Allylation Approach to the Total Synthesis of the Medium-Ring Dilactone (+)-Antimycin A1b
2014Co-Authors: John Janetzko, Robert A. BateyAbstract:The stereoselective synthesis of (+)-antimycin A1b has been accomplished in 12 linear steps and 18% overall yield from (−)-ethyl lactate. A robust, scalable, and highly diastereoselective montmorillonite K10-promoted allylation reaction between an α-silyloxy aldehyde and a substituted potassium allyltrifluoroborate salt provides a general approach to the core stereochemical triad of the antimycin A family. The requisite (Z)-substituted potassium allyltrifluoroborate salt was synthesized using a syn-selective hydroboration/protodeboration of an alkynylboronate ester, followed by a Matteson Homologation reaction. The total synthesis leverages an MNBA (Shiina’s reagent)-mediated macrolactonization to generate the 9-membered dilactone ring and a late-stage PyBOP-mediated amide coupling employing an unprotected 3-formamidosalicylic acid fragment, thereby shortening the longest linear sequence and, perhaps most notably, generating the antimycin A C7–C8–C9 stereotriad in a single step using a single chiral pool-derived stereocenter
Varinder K. Aggarwal - One of the best experts on this subject based on the ideXlab platform.
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(-)-Cytisine: Access to a stereochemically defined and functionally flexible piperidine scaffold.
Organic & biomolecular chemistry, 2018Co-Authors: Worawat Niwetmarin, Varinder K. Aggarwal, Hugo Rego Campello, Hazel A. Sparkes, Timothy GallagherAbstract:N-Benzyl cytisine undergoes an efficient C(6)-N(7) cleavage via directed C(6) lithiation, borylation and oxidation to provide a "privileged" heterocyclic core unit comprising a highly functionalised, cis-3,5-disubstituted piperidine in enantiomerically pure form. The potential offered by this unit as a means to explore chemical space has been evaluated and methods have been defined (and illustrated) that allow for selective manipulation of N(1), C(3'), and the pyridone N. The pyridone core can also be diversified via bromination (at C(3'') and C(5'')) which is complementary to direct C-H activation based on Ir-catalyzed borylation to provide access to C(4''). The use of a boronate-based 1,2-migration as an alternative trigger to mediate C(6)-N(7) cleavage of cytisine was evaluated but failed. However, the stability of the intermediate boronate opens a new pathway for the elaboration of cytisine itself using both Matteson Homologation and Zweifel olefination.
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Short Enantioselective Total Synthesis of Tatanan A and 3‐epi‐Tatanan A Using Assembly‐Line Synthesis
Angewandte Chemie (International ed. in English), 2016Co-Authors: Adam Noble, Stefan Roesner, Varinder K. AggarwalAbstract:Short and highly stereoselective total syntheses of the sesquilignan natural product tatanan A and its C3 epimer are described. An assembly-line synthesis approach, using iterative lithiation–borylation reactions, was applied to install the three contiguous stereocenters with high enantio- and diastereoselectivity. One of the stereocenters was installed using a configurationally labile lithiated primary benzyl benzoate, resulting in high levels of substrate-controlled (undesired) diastereoselectivity. However, reversal of selectivity was achieved by using a novel diastereoselective Matteson Homologation. Stereospecific alkynylation of a hindered secondary benzylic boronic ester enabled completion of the synthesis in a total of eight steps.
Uli Kazmaier - One of the best experts on this subject based on the ideXlab platform.
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A Straightforward Synthesis of Polyketides via Ester Dienolate Matteson Homologation
Chemistry (Weinheim an der Bergstrasse Germany), 2020Co-Authors: Oliver Andler, Uli KazmaierAbstract:Application of ester dienolates as nucleophiles in Matteson Homologations allows for the stereoselective synthesis of highly substituted α,β-unsaturated δ-hydroxy carboxyl acids, structural motifs widespread found in polyketide natural products. The protocol is rather flexible and permits the introduction of substituents and functionalities also at those positions which are not accessible by the commonly used aldol reaction. Therefore, this ester dienolate Matteson approach is an interesting alternative to the "classical" polyketide syntheses.
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Matteson Homologation-Based Total Synthesis of Lagunamide A.
Organic letters, 2018Co-Authors: Jan Gorges, Uli KazmaierAbstract:Matteson Homologation was found to be an excellent tool for the synthesis of the polyketide fragment of lagunamide A. Starting from a chiral boronic ester, a central building block containing all stereogenic centers of the polyketide chain was synthesized via six iterative Matteson Homologation steps.
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Matteson Homologation-Based Total Synthesis of Lagunamide A
2018Co-Authors: Jan Gorges, Uli KazmaierAbstract:Matteson Homologation was found to be an excellent tool for the synthesis of the polyketide fragment of lagunamide A. Starting from a chiral boronic ester, a central building block containing all stereogenic centers of the polyketide chain was synthesized via six iterative Matteson Homologation steps
John Janetzko - One of the best experts on this subject based on the ideXlab platform.
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Organoboron-Based Allylation Approach to the Total Synthesis of the Medium-Ring Dilactone (+)-Antimycin A1b
The Journal of organic chemistry, 2014Co-Authors: John Janetzko, Robert A. BateyAbstract:The stereoselective synthesis of (+)-antimycin A1b has been accomplished in 12 linear steps and 18% overall yield from (−)-ethyl lactate. A robust, scalable, and highly diastereoselective montmorillonite K10-promoted allylation reaction between an α-silyloxy aldehyde and a substituted potassium allyltrifluoroborate salt provides a general approach to the core stereochemical triad of the antimycin A family. The requisite (Z)-substituted potassium allyltrifluoroborate salt was synthesized using a syn-selective hydroboration/protodeboration of an alkynylboronate ester, followed by a Matteson Homologation reaction. The total synthesis leverages an MNBA (Shiina’s reagent)-mediated macrolactonization to generate the 9-membered dilactone ring and a late-stage PyBOP-mediated amide coupling employing an unprotected 3-formamidosalicylic acid fragment, thereby shortening the longest linear sequence and, perhaps most notably, generating the antimycin A C7–C8–C9 stereotriad in a single step using a single chiral pool-...
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Organoboron-Based Allylation Approach to the Total Synthesis of the Medium-Ring Dilactone (+)-Antimycin A1b
2014Co-Authors: John Janetzko, Robert A. BateyAbstract:The stereoselective synthesis of (+)-antimycin A1b has been accomplished in 12 linear steps and 18% overall yield from (−)-ethyl lactate. A robust, scalable, and highly diastereoselective montmorillonite K10-promoted allylation reaction between an α-silyloxy aldehyde and a substituted potassium allyltrifluoroborate salt provides a general approach to the core stereochemical triad of the antimycin A family. The requisite (Z)-substituted potassium allyltrifluoroborate salt was synthesized using a syn-selective hydroboration/protodeboration of an alkynylboronate ester, followed by a Matteson Homologation reaction. The total synthesis leverages an MNBA (Shiina’s reagent)-mediated macrolactonization to generate the 9-membered dilactone ring and a late-stage PyBOP-mediated amide coupling employing an unprotected 3-formamidosalicylic acid fragment, thereby shortening the longest linear sequence and, perhaps most notably, generating the antimycin A C7–C8–C9 stereotriad in a single step using a single chiral pool-derived stereocenter
Yian Guo - One of the best experts on this subject based on the ideXlab platform.
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Total Synthesis of Dysoxylactam A.
Organic letters, 2020Co-Authors: Mingze Yang, Peng Wenquan, Yian GuoAbstract:The total synthesis of a potent multi-drug-resistant reverser, dysoxylacatam A (1), was achieved in a highly efficient and stereocontrolled fashion. The highlights of the strategy enlisted an iterative combination of lithiation-borylation tactics including Aggarwal Homologation and Matteson Homologation, Brown crotylation, Krische allylation, and ring-closing metathesis to forge the macrocycle.