- Vinyl-allenes as dienes in the Lewis acid-mediated hetero Diels-Alder reaction with aldehydes
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The Lewis acid-mediated, hetero Diels-Alder reaction of a vinyl-allene system with aldehydes as heterodienophiles has been carried out. In the cases studied, only two cycloadducts have been obtained, which correspond to the endo (major compound) and exo (minor compound) approach of the aldehyde through the less hindered face of the dienic system. (C) 2000 Elsevier Science Ltd.
- Regas,Afonso,Galindo,Palenzuela
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- Synthesis of Highly Substituted Pyridines via [4 + 2] Cycloadditions of Vinylallenes and Sulfonyl Cyanides
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A convergent strategy for the synthesis of multisubstituted pyridines is described. Vinylallenes combine with commercially available arylsulfonyl cyanides in Diels-Alder cycloadditions to generate isopyridine cycloadducts that are converted to pyridines upon further heating or addition of a base. The 2-sulfonylpyridine products undergo nucleophilic aromatic substitution reactions with oxygen and carbon nucleophiles to provide access to a variety of highly substituted pyridines.
- Bartko, Samuel G.,Hamzik, Phillip J.,Espindola, Leandro,Gomez, Christian,Danheiser, Rick L.
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supporting information
p. 548 - 563
(2019/12/27)
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- One-Pot Access to 1,7a-Dihydro-1,3a-ethano-indene and 1,8a-Dihydro-1,3a-ethano-azulene Skeletons by a Sequential Gold(I)-Catalyzed Propargyl Claisen Rearrangement/Nazarov Cyclization/[4+2] Cycloaddition Reaction
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An efficient synthetic approach to the tricyclic 1,7a-dihydro-1,3a-ethano-indene and 1,8a-dihydro-1,3a-ethano-azulene skeletons from suitable propargyl vinyl ethers is based on a one-pot, multistep process entailing a gold(I)-catalyzed propargyl Claisen rearrangement/Nazarov cyclization, a [4+2] cycloaddition of the formed six-or seven-membered ring-fused cyclopentadiene system, and a final protection step for the easy isolation and purification of the products by chromatography.
- Langé, Vittoria,Occhiato, Ernesto G.,Rinaldi, Antonia,Scarpi, Dina
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p. 5078 - 5086
(2020/05/01)
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- Lipase-catalyzed asymmetric synthesis of naphtho[2,3-c]furan-1(3H)-one derivatives by a one-pot dynamic kinetic resolution/intramolecular Diels–Alder reaction: Total synthesis of (?)-himbacine
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One-pot sequential reactions using the acyl moieties installed by enzymatic dynamic kinetic resolution of alcohols have been little investigated. In this work, the acryloyl moiety installed via the lipase/oxovanadium combo-catalyzed dynamic kinetic resolution of a racemic dienol [4-(cyclohex-1-en-1-yl)but-3-en-2-ol or 1-(cyclohex-1-en-1-yl)but-2-en-1-ol] with a (Z)-3-(phenylsulfonyl)acrylate underwent an intramolecular Diels–Alder reaction in a one-pot procedure to produce an optically active naphtho[2,3-c]furan-1(3H)-one derivative (98% ee). This method was successfully applied to the asymmetric total synthesis of (?)-himbacine.
- Sugiyama, Koji,Kawanishi, Shinji,Oki, Yasuhiro,Kamiya, Marin,Hanada, Ryosuke,Egi, Masahiro,Akai, Shuji
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p. 1378 - 1386
(2017/10/06)
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- Pentannulation Reaction by Tandem Gold(I)-Catalyzed Propargyl Claisen Rearrangement/Nazarov Cyclization of Enynyl Vinyl Ethers
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The tandem gold(I)-catalyzed propargyl Claisen rearrangement/Nazarov cyclization of propargyl vinyl ether derivatives, followed by in situ reduction of the resulting carbonyl group, provides functionalized cyclopentadienes fused with various N-hetero- and
- Rinaldi, Antonia,Petrovi?, Martina,Magnolfi, Stefano,Scarpi, Dina,Occhiato, Ernesto G.
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supporting information
p. 4713 - 4717
(2018/08/09)
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- One-pot synthesis of optically active allyl esters via lipase-vanadium combo catalysis
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The combination of vanadium-oxo compounds (3 or 4) with a lipase produced the regio- and enantioconvergent transformation of racemic allyl alcohols (1 or 2) into optically active allyl esters. In this system, the vanadium compounds catalyzed the continuous racemization of the alcohols along with the transposition of the hydroxyl group, while the lipase effected the chemo- and enantioselective esterification to achieve the dynamic kinetic resolution.
- Akai, Shuji,Hanada, Ryosuke,Fujiwara, Noboru,Kita, Yasuyuki,Egi, Masahiro
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supporting information; experimental part
p. 4900 - 4903
(2011/01/12)
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- B(C6F5)3-catalyzed allylation of propargyl acetates with allylsilanes.
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[reaction: see text] An efficient method for the B(C(6)F(5))(3)-catalyzed allylation of secondary propargylic alcohol derivatives with allylsilanes has been developed. This method allows for the facile synthesis of a variety of 1,5-enynes in good to high yields with a number of functionalities, such as nitro, chloro, ester, and boronic ester, being tolerated under the reaction conditions.
- Schwier, Todd,Rubin, Michael,Gevorgyan, Vladimir
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p. 1999 - 2001
(2007/10/03)
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- PMHS-mediated couplings of alkynes or benzothiazoles with various electrophiles: Application to the synthesis of (-)-akolactone A
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Polymethylhydrosiloxane (PMHS) in combination with CsF facilitates the cross-coupling of alkynes or benzothiazoles with an array of vinyl, styryl, and aryl halides or nonaflates as well as acid chlorides. Experimental and spectroscopic evidence indicates that these reactions involve the in situ generation of a siloxyl intermediate. These cross-couplings proceed relatively quickly at room temperature and under amine-free conditions. To demonstrate the applicability of the method, a total synthesis of the cyctotoxic butanolide (-)-akolactone A was carried out.
- Gallagher, William P.,Maleczka Jr., Robert E.
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p. 6775 - 6779
(2007/10/03)
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- Polymethylhydrosiloxane (PMHS) as an additive in Sonogashira reactions
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Polymethylhydrosiloxane (PMHS) in combination with CsF facilitates the Sonogashira reaction of a variety of alkynes and electrophiles. These couplings appear to involve the in situ formation and reaction of an alkynylsiloxane. Such couplings can be run am
- Gallagher, William P.,Maleczka Jr., Robert E.
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p. 537 - 541
(2007/10/03)
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- Synthesis of octahydroquinolines through the Lewis acid catalyzed reaction of vinyl allenes and imines
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The reaction of vinyl allenes with imines under Lewis acid catalysis has been explored. Vinyl allenes in which the allenic portion of the molecule is tri- or tetrasubstituted gave octahydroquinoline derivatives as single isomers together with a minor comp
- Regas, David,Afonso, Maria M.,Rodriguez, Matias L.,Palenzuela, J. Antonio
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p. 7845 - 7852
(2007/10/03)
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- Synthesis of Glucosides Related to Grape and Wine Aroma Precursors
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Syntheses of the following glucosides are reported: 3',5',5'-trimethyl-3'-cyclohexenyl β-D-glucopyranoside, 3'-(1"-cyclohexenyl)-1'-methyl-2'-propynyl β-D-glucopyranoside, (3'R*,9'S*)-3'-hydroxy-5'-megastigmen-7'-yn-9'-yl β-D-glucopy
- Skouroumounis, George K,Massey-Westrop, Ralph A.,Sefton, Mark A.,Williams, Patrick J.
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p. 974 - 980
(2007/10/02)
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