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Bertrand Carboni - One of the best experts on this subject based on the ideXlab platform.
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a diastereoselective route to trans 2 aryl 2 3 dihydrobenzofurans through sequential cross metathesis isomerization Allylboration reactions synthesis of bioactive neolignans
European Journal of Organic Chemistry, 2015Co-Authors: Rémy Hemelaere, François Carreaux, Bertrand CarboniAbstract:A new highly diastereoselective synthetic route to trans-2,3-dihydrobenzofuran systems, in particular those bearing an aryl substituent at the C2 position, is described. The cornerstone of our strategy is the implementation of a cross-metathesis/isomerization/Allylboration sequence starting from 2-allyl-substituted phenols and aldehydes. After an intramolecular Mitsunobu cyclization step, the anti-homoallylic alcohols allow the synthesis of the desired skeleton in a stereoselective fashion. As an illustration, we used this strategy for the preparation of the dihydrodehydrodiconiferyl alcohol (1a), a natural dihydrobenzofuran neolignan, as well as for a formal synthesis of its O-demethylated derivative 1b. An enantioselective version of this approach employing a chiral phosphoric acid in the Allylboration step is also studied.
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cross metathesis isomerization Allylboration sequence for a diastereoselective synthesis of anti homoallylic alcohols from allylbenzene derivatives and aldehydes
ChemInform, 2015Co-Authors: Rémy Hemelaere, François Carreaux, Bertrand CarboniAbstract:A reaction sequence consisting of cross-metathesis of allylarenes with vinylboronic acid, Ir-catalyzed isomerization and Allylboration to give homoallylic alcohols (IV) with excellent diastereoselectivity.
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Cross‐Metathesis/Isomerization/Allylboration Sequence for a Diastereoselective Synthesis of anti‐Homoallylic Alcohols from Allylbenzene Derivatives and Aldehydes.
ChemInform, 2015Co-Authors: Rémy Hemelaere, François Carreaux, Bertrand CarboniAbstract:A reaction sequence consisting of cross-metathesis of allylarenes with vinylboronic acid, Ir-catalyzed isomerization and Allylboration to give homoallylic alcohols (IV) with excellent diastereoselectivity.
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A Diastereoselective Route to trans‐2‐Aryl‐2,3‐dihydrobenzofurans through Sequential Cross‐Metathesis/Isomerization/Allylboration Reactions: Synthesis of Bioactive Neolignans
European Journal of Organic Chemistry, 2015Co-Authors: Rémy Hemelaere, François Carreaux, Bertrand CarboniAbstract:A new highly diastereoselective synthetic route to trans-2,3-dihydrobenzofuran systems, in particular those bearing an aryl substituent at the C2 position, is described. The cornerstone of our strategy is the implementation of a cross-metathesis/isomerization/Allylboration sequence starting from 2-allyl-substituted phenols and aldehydes. After an intramolecular Mitsunobu cyclization step, the anti-homoallylic alcohols allow the synthesis of the desired skeleton in a stereoselective fashion. As an illustration, we used this strategy for the preparation of the dihydrodehydrodiconiferyl alcohol (1a), a natural dihydrobenzofuran neolignan, as well as for a formal synthesis of its O-demethylated derivative 1b. An enantioselective version of this approach employing a chiral phosphoric acid in the Allylboration step is also studied.
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A Diastereoselective Route to trans-2-Aryl-2,3-dihydrobenzofurans through Sequential Cross-Metathesis/Isomerization/Allylboration Reactions: Synthesis of Bioactive Neolignans
European Journal of Organic Chemistry, 2015Co-Authors: Rémy Hemelaere, François Carreaux, Bertrand CarboniAbstract:A new highly diastereoselective synthetic route to trans-2,3-dihydrobenzofuran systems, in particular those bearing an aryl substituent at the C2 position, is described. The cornerstone of our strategy is the implementation of a cross-metathesis/isomerization/Allylboration sequence starting from 2-allyl-substituted phenols and aldehydes. After an intramolecular Mitsunobu cyclization step, the anti-homoallylic alcohols allow the synthesis of the desired skeleton in a stereoselective fashion. As an illustration, we used this strategy for the preparation of the dihydrodehydrodiconiferyl alcohol (1a), a natural dihydrobenzofuran neolignan, as well as for a formal synthesis of its O-demethylated derivative 1b. An enantioselective version of this approach employing a chiral phosphoric acid in the Allylboration step is also studied.
Dennis G. Hall - One of the best experts on this subject based on the ideXlab platform.
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Allylboration of Carbonyl Compounds
2012Co-Authors: Hugo Lachance, Dennis G. HallAbstract:Allylic boron compounds have gained a prominent status in organic synthesis for their ability to add with high stereoselectivity to carbonyl compounds such as aldehydes, making them a methodology of choice for the preparation of acetate and propionate units found in several classes of natural products. This remarkable reaction process was discovered in 1964, only to become popular in the 1980s. Using either the dialkylborane or boronate reagents, both the thermal uncatalyzed reaction and the more recent acid-catalyzed procedures can provide homoallylic alcohol products in high enantioselectivity. The wide of range of possibilities for substitution on the reagent's allylic unit has led to the development of numerous reagents, and the residual alkene unit in the products confers to Allylboration chemistry a unique versatility. This chapter presents an exhaustive survey of the useful reagents and their associated carbonyl substrates employed in organic synthesis. The mechanisms and parameters of the reaction are discussed, along with an overview of the different preparative methods for allylic boron reagents. The scope and limitations of these reagents in enantioselective additions, doubly diastereoselective additions, tandem reactions, and other variants is emphasized in the context of applications in natural product synthesis. The literature is covered through early 2006. Keywords: aldehydes; allylation; boron reagents; homoallylic alcohols; nucleophilic additions; organoboron chemistry; stereoselectivity
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Rationally improved chiral Brønsted acid for catalytic enantioselective Allylboration of aldehydes with an expanded reagent scope.
The Journal of organic chemistry, 2009Co-Authors: Vivek Rauniyar, Dennis G. HallAbstract:One of the most useful reactions in organic synthesis, the stereocontrolled addition of allylic metal reagents to carbonyl compounds, provides access to enantiomerically enriched homoallylic alcohols related to the acetate, propionate, and other oxygen-containing functionalities present in a large number of biologically active natural products and pharmaceutical drugs. In the search for an ideal carbonyl allylation methodology, the catalytic enantioselective Allylboration presents numerous advantages such as a high chemo-, diastereo-, and enantiocontrol with stable and nontoxic pinacol allylic boronates. This article reports a rationally improved diol x SnCl(4) complex as chiral protic acid catalyst, which provides unprecedented levels of enantioselectivity in the catalytic allylation, methallylation, crotylation, and 2-bromoallylation of aliphatic aldehydes. The new diol, p-F-Vivol (4b), enables a more active diol x SnCl(4) catalyst that can compete more effectively with the background uncatalyzed Allylboration. The usefulness of this optimized catalytic Allylboration methodology was demonstrated with an efficient synthesis of the naturally occurring pyranone (+)-dodoneine and to the preparation of biologically important exomethylene-gamma-lactones.
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New preparative methods for allylic boronates and their application in stereoselective catalytic Allylborations
Pure and Applied Chemistry, 2008Co-Authors: Dennis G. HallAbstract:Stereocontrolled additions of allylic metal reagents to carbonyl compounds consti- tute one of the most useful classes of transformations in organic synthesis. The recent devel- opment of Lewis and Bronsted acid-catalyzed manifolds for the Allylboration of carbonyl compounds has opened doors toward an ideal carbonyl allylation methodology using stable and nontoxic allylic boronates as reagents. This paper describes the development of acid-cat- alyzed Allylborations, mechanistic investigations of these new processes, and ongoing efforts toward general catalytic enantioselective Allylboration methodologies. The preparation of op- tically enriched α-substituted allylic boronate reagents is discussed, as well as their applica- tions in Lewis acid-catalyzed additions to afford skeletally diverse products like propionate units, polysubstituted furans, vinylcyclopropanes, and larger ring systems.
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Lewis and Brønsted Acid Catalyzed Allylboration of Carbonyl Compounds: From Discovery to Mechanism and Applications
Synlett, 2007Co-Authors: Dennis G. HallAbstract:The recent development of Lewis and Bronsted acid -catalyzed manifolds for the Allylboration of carbonyl compounds has opened doors towards an ideal carbonyl allylation methodology using stable and nontoxic allylic boronates as reagents. This -Account relates our laboratory’s discovery of acid-catalyzed allyl-borations, mechanistic investigations of these new processes, and ongoing efforts by our group and others towards a general catalytic enantioselective Allylboration methodology. 1 Introduction 2 Discovery and Development of Catalyzed Allylborations with 2-Alkoxycarbonyl Allylic Boronates 2.1 Lewis Acid Catalyzed Allylboration 2.2 Bronsted Acid Catalyzed Allylboration 3 Mechanistic Considerations 4 Stoichiometric Approaches to Enantiocontrolled -Allylboration of Aldehydes 5 Catalytic Methods for Enantioselective Allylborations 6 Lewis Acid Catalyzed Additions of α-Substituted Allylic Boronates 7 Conclusion
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Preparation of a C2-Symmetric Binol-Derived Diol and Its Application in the Catalytic Enantioselective and Catalyst-Controlled Diastereoselective Allylboration of Aldehydes
Synthesis, 2007Co-Authors: Vivek Rauniyar, Dennis G. HallAbstract:A novel C 2 -symmetric Binol-derived diol is described. It is readily applicable towards combined acid catalysis for the asym-metric Allylboration of aldehydes to provide homoallylic alcohols in high enantioselectivities, and dictates the diastereoselectivity in the reaction of an achiral allylboronate with chiral aldehydes.
Yuri N. Bubnov - One of the best experts on this subject based on the ideXlab platform.
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Design of bicyclic and cage boron compounds based on Allylboration of acetylenes with allyldichloroboranes.
Organic letters, 2009Co-Authors: Sergey Yu Erdyakov, Mikhail E. Gurskii, Konstantin A Lyssenko, Anatolii V. Ignatenko, T. V. Potapova, Yuri N. BubnovAbstract:Allylboration of acetylenes with allyldichloroboranes has been proposed as a first step of allylboron−acetylene condensation and a way to design condensation products from stage to stage. The chemistry has been applied to the synthesis of isomeric 3-borabicyclo[3.3.1]non-6-enes transformed into 3-methyl-1-boraadamantane and [5-D]-3-methyl-1-boraadamantane derivatives.
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First Allylboration of organic compounds with the NN double bond. Synthesis of N-allylpyrazolidines and allyl-1,2-diphenylhydrazine
Journal of Organometallic Chemistry, 2009Co-Authors: Ivan P. Klimenko, Andrey Medvedev, Victor A. Korolev, G. D. Kolomnikova, Yury V. Tomilov, Yuri N. BubnovAbstract:Abstract Triallylborane adds to the N N double bond of pyrazolines 1 and 2 at 0 °C giving after deboronation the corresponding N -allylpyrazolidines 4 and 5 . Further transformations of allylpyrazolidine 4 including the cyclopropane ring opening were studied. Allylboration of azobenzene with triallylborane gives rise to 1-allyl-1,2-diphenylhydrazine.
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synthesis of nitrogen containing spiro compounds from lactams by Allylboration and subsequent ring closing metathesis
European Journal of Organic Chemistry, 2004Co-Authors: Piotr Nieczypor, Johannes C. Mol, Natalia B. Bespalova, Yuri N. BubnovAbstract:A series of nitrogen-containing spiro[4.n]alkenes was prepared with excellent yields starting from lactams in two steps: Allylboration on the carbonyl carbon and subsequent ring-closing metathesis of the 2,2-diallyl N-heterocycles. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
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Synthesis of Nitrogen‐Containing Spiro Compounds from Lactams by Allylboration and Subsequent Ring‐Closing Metathesis
European Journal of Organic Chemistry, 2004Co-Authors: Piotr Nieczypor, Johannes C. Mol, Natalia B. Bespalova, Yuri N. BubnovAbstract:A series of nitrogen-containing spiro[4.n]alkenes was prepared with excellent yields starting from lactams in two steps: Allylboration on the carbonyl carbon and subsequent ring-closing metathesis of the 2,2-diallyl N-heterocycles. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
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Reaction of 1-alkynylsilanes with triallylborane—competition between 1,1- and 1,2-Allylboration
Journal of Organometallic Chemistry, 1999Co-Authors: Bernd Wrackmeyer, Oleg L. Tok, Yuri N. BubnovAbstract:Abstract The reaction of triallylborane (All 3 B, 1) with various 1-alkynylsilanes of the type Me 3 Si–CCR 1 [R 1 =H ( 2a ), Me ( 2b ), Ph ( 2c ), CC–SiMe 3 ( 2d ), SiMe 3 ( 2e )], Ph 3 Si–CCPh ( 3 ) MeCC–SiMe 2 SiMe 2 –CCMe ( 4 ) and Me 2 Si(Cl)–CCPh ( 5 ) was studied. Triallylborane 1 turned out to be much more reactive than other triorganoboranes R 3 B (e.g. R=Et, Ph). In the cases of 2 and 5 , the products are organometallic-substituted alkenes 6 and 11 , respectively, with the boryl and silyl group in cis -positions as the result of selective 1,1-Allylboration (via cleavage of the Si–C bond) or mixtures of such and other alkenes 7 or 8 because of competition between 1,1- and 1,2-Allylboration (the composition of these mixtures depends on the polarity of the solvent). In the case of 4 , the 1,2-dihydro-1,2-disilaborepine derivative 12 is formed selectively (twofold 1,1-Allylboration). The alkyne 3 did not react with 1 . The products were characterised by 1 H-, 11 B-, 13 C- and 29 Si-NMR spectroscopy.
Monica Bassous - One of the best experts on this subject based on the ideXlab platform.
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asymmetric Allylboration of aldehydes with pinacol allylboronates catalyzed by 1 1 spirobiindane 7 7 diol spinol based phosphoric acids
European Journal of Organic Chemistry, 2012Co-Authors: Chun-hui Xing, Yimei Zhang, Darya Sabarova, Yuanxi Liao, Monica BassousAbstract:The asymmetric Allylboration of aldehydes with pinacolallylboronates catalyzed by 1,1′-spirobiindane-7,7′-diol (SPINOL) based phosphoric acids is described. 6,6′-Bis(2,4,6-triisopropylphenyl)SPINOL-based phosphoric acid was found to be a general, highly enantioselective catalyst for such Allylboration reactions and excellent enantioselectivities were obtained for different types of aldehydes including aromatic aldehydes, α,β-unsaturated aldehydes, propargylic aldehydes, and aliphatic aldehydes.
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Asymmetric Allylboration of Aldehydes with Pinacol Allylboronates Catalyzed by 1,1′‐Spirobiindane‐7,7′‐diol (SPINOL) Based Phosphoric Acids
European Journal of Organic Chemistry, 2012Co-Authors: Chun-hui Xing, Yuan‐xi Liao, Yimei Zhang, Darya Sabarova, Monica BassousAbstract:The asymmetric Allylboration of aldehydes with pinacolallylboronates catalyzed by 1,1′-spirobiindane-7,7′-diol (SPINOL) based phosphoric acids is described. 6,6′-Bis(2,4,6-triisopropylphenyl)SPINOL-based phosphoric acid was found to be a general, highly enantioselective catalyst for such Allylboration reactions and excellent enantioselectivities were obtained for different types of aldehydes including aromatic aldehydes, α,β-unsaturated aldehydes, propargylic aldehydes, and aliphatic aldehydes.
François Carreaux - One of the best experts on this subject based on the ideXlab platform.
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a diastereoselective route to trans 2 aryl 2 3 dihydrobenzofurans through sequential cross metathesis isomerization Allylboration reactions synthesis of bioactive neolignans
European Journal of Organic Chemistry, 2015Co-Authors: Rémy Hemelaere, François Carreaux, Bertrand CarboniAbstract:A new highly diastereoselective synthetic route to trans-2,3-dihydrobenzofuran systems, in particular those bearing an aryl substituent at the C2 position, is described. The cornerstone of our strategy is the implementation of a cross-metathesis/isomerization/Allylboration sequence starting from 2-allyl-substituted phenols and aldehydes. After an intramolecular Mitsunobu cyclization step, the anti-homoallylic alcohols allow the synthesis of the desired skeleton in a stereoselective fashion. As an illustration, we used this strategy for the preparation of the dihydrodehydrodiconiferyl alcohol (1a), a natural dihydrobenzofuran neolignan, as well as for a formal synthesis of its O-demethylated derivative 1b. An enantioselective version of this approach employing a chiral phosphoric acid in the Allylboration step is also studied.
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cross metathesis isomerization Allylboration sequence for a diastereoselective synthesis of anti homoallylic alcohols from allylbenzene derivatives and aldehydes
ChemInform, 2015Co-Authors: Rémy Hemelaere, François Carreaux, Bertrand CarboniAbstract:A reaction sequence consisting of cross-metathesis of allylarenes with vinylboronic acid, Ir-catalyzed isomerization and Allylboration to give homoallylic alcohols (IV) with excellent diastereoselectivity.
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Cross‐Metathesis/Isomerization/Allylboration Sequence for a Diastereoselective Synthesis of anti‐Homoallylic Alcohols from Allylbenzene Derivatives and Aldehydes.
ChemInform, 2015Co-Authors: Rémy Hemelaere, François Carreaux, Bertrand CarboniAbstract:A reaction sequence consisting of cross-metathesis of allylarenes with vinylboronic acid, Ir-catalyzed isomerization and Allylboration to give homoallylic alcohols (IV) with excellent diastereoselectivity.
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A Diastereoselective Route to trans‐2‐Aryl‐2,3‐dihydrobenzofurans through Sequential Cross‐Metathesis/Isomerization/Allylboration Reactions: Synthesis of Bioactive Neolignans
European Journal of Organic Chemistry, 2015Co-Authors: Rémy Hemelaere, François Carreaux, Bertrand CarboniAbstract:A new highly diastereoselective synthetic route to trans-2,3-dihydrobenzofuran systems, in particular those bearing an aryl substituent at the C2 position, is described. The cornerstone of our strategy is the implementation of a cross-metathesis/isomerization/Allylboration sequence starting from 2-allyl-substituted phenols and aldehydes. After an intramolecular Mitsunobu cyclization step, the anti-homoallylic alcohols allow the synthesis of the desired skeleton in a stereoselective fashion. As an illustration, we used this strategy for the preparation of the dihydrodehydrodiconiferyl alcohol (1a), a natural dihydrobenzofuran neolignan, as well as for a formal synthesis of its O-demethylated derivative 1b. An enantioselective version of this approach employing a chiral phosphoric acid in the Allylboration step is also studied.
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A Diastereoselective Route to trans-2-Aryl-2,3-dihydrobenzofurans through Sequential Cross-Metathesis/Isomerization/Allylboration Reactions: Synthesis of Bioactive Neolignans
European Journal of Organic Chemistry, 2015Co-Authors: Rémy Hemelaere, François Carreaux, Bertrand CarboniAbstract:A new highly diastereoselective synthetic route to trans-2,3-dihydrobenzofuran systems, in particular those bearing an aryl substituent at the C2 position, is described. The cornerstone of our strategy is the implementation of a cross-metathesis/isomerization/Allylboration sequence starting from 2-allyl-substituted phenols and aldehydes. After an intramolecular Mitsunobu cyclization step, the anti-homoallylic alcohols allow the synthesis of the desired skeleton in a stereoselective fashion. As an illustration, we used this strategy for the preparation of the dihydrodehydrodiconiferyl alcohol (1a), a natural dihydrobenzofuran neolignan, as well as for a formal synthesis of its O-demethylated derivative 1b. An enantioselective version of this approach employing a chiral phosphoric acid in the Allylboration step is also studied.
