- General synthesis of 2-alkyn-1-ylboronates in excellent isomeric purity
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2-Alkyn-1-ylboronates have been synthesized successfully, in excellent isomeric purity, via the in situ homologation of alkyn-1-ylboronates with LiCH2I. The relative reactivities exhibited by various LiCH2X reagents (X = Cl; Br; I) are described.
- Soundararajan, Raman,Li, Guisheng,Brown, Herbert C.
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- Gold(I)-catalyzed rearrangement of alkynylaziridine indoles for the synthesis of spiro-tetrahydro-β-carbolines
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Functionalized spiro-tetrahydro-β-carbolines were formed by an efficient gold(I)-catalyzed rearrangement reaction of alkynylaziridine indoles. The reaction involved a Friedel-Crafts type intramolecular reaction of alkynylaziridine indoles, following by hydroamination of aminoallene intermediate.
- Yang, Yan-Fang,Li, Lian-Hua,He, Yu-Tao,Luo, Jian-Yi,Liang, Yong-Min
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supporting information
p. 702 - 707
(2014/02/14)
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- Coinage metals-catalyzed cascade reactions of aryl alkynylaziridines: Silver(I)-single vs gold(I)-double cyclizations
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Alkynylaziridines carrying an aryl group could be efficiently converted into aminoallenylidene isochromans, isoquinolines, or tetrahydronaphtalenes with silver(I) salts and into 1-azaspiro[4.5]decane derivatives with gold(I) complexes. Mechanistic investi
- Kern, Nicolas,Blanc, Aurelien,Miaskiewicz, Solene,Robinette, Michelle,Weibel, Jean-Marc,Pale, Patrick
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experimental part
p. 4323 - 4341
(2012/06/18)
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- Silver(I)-Catalyzed deprotection of p -methoxybenzyl ethers: A mild and chemoselective method
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The p-methoxybenzyl protecting group (PMB) on various alcohols and an acid was efficiently and selectively cleaved by the action of a catalytic amount of silver(I) hexafluoroantimonate combined with 0.5 equiv of 1,3,5- trimethoxybenzene in dichloromethane at 40 °C.
- Kern, Nicolas,Dombray, Thomas,Blanc, Aurelien,Weibel, Jean-Marc,Pale, Patrick
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p. 9227 - 9235,9
(2012/12/12)
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- Reactivity pattern of bis(propargyloxy) disulfides: Tandem rearrangements and cyclizations
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Thirty-five substituted bis(propargyloxy) disulfides were successfully prepared in good to excellent yields, and their reactivity was found to be strongly dependent on the substitution pattern of the reactant. Inter alia they undergo surprising tandem sigmatropic rearrangements and cycloadditions. Three heretofore unknown product types were isolated and fully characterized: 6,7-dithiabicyclo[3.1.1]heptan-2-one 6-oxide derivatives, two isomeric 1,2-dithiete 1,1-dioxides (α,β-unsaturated four-membered cyclic thiosulfonates) from bis(propargyloxy) disulfides with α- or γ-alkyl-substituted propargyl groups, and two isomeric 2-oxa-5,7-dithiabicyclo[2.2.1]heptane 5-oxides from bis(propargyloxy) disulfides with α-tert-butyl- or α,α-dialkyl-substituted propargyl groups. Georg Thieme Verlag Stuttgart - New York.
- Braverman, Samuel,Pechenick-Azizi, Tatiana,Gottlieb, Hugo E.,Sprecher, Milon
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experimental part
p. 1741 - 1750
(2011/07/09)
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- Gold(i)-catalyzed rearrangement of aryl alkynylaziridines to spiro[isochroman-4,2′-pyrrolines]
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Alkynylaziridines carrying an aryl group could be efficiently converted to spiro[isochroman-4,2′-pyrrolines] with gold salts as catalysts. This new rearrangement involved a Friedel-Crafts type intramolecular reaction followed by cyclization of the aminoallene intermediate, both initiated by the dual σ and π Lewis acidities of gold.
- Kern, Nicolas,Blanc, Aurelien,Weibel, Jean-Marc,Pale, Patrick
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supporting information; experimental part
p. 6665 - 6667
(2011/06/25)
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- Intramolecular pyridone/enyne photocycloaddition: Partitioning of the [4 + 4] and [2 + 2] pathways
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Chemical equations presented. Intramolecular photocycloaddition (>290 nm) between a 1,3-enyne and a 2-pyridone is far more selective than the intermolecular version; a three-atom linkage both controls regiochemistry and separates the [2 + 2] and [4 + 4] pathways. All four head-to-head, head-to-tail, tail-to-head, and tail-to-tail tetherings have been investigated. Linkage via the ene of the enyne leads to [2 + 2] products regardless of alkene geometry, whereas linkage through the yne results in [4 + 4] cycloadducts. The bridged 1,2,5-cyclooctatriene products of [4 + 4] cycloaddition are unstable and undergo a subsequent [2 + 2] dimerization reaction.
- Kulyk, Svitlana,Dougherty, William G.,Kassel, W. Scott,Zdilla, Michael J.,Sieburth, Scott M.
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supporting information; experimental part
p. 2180 - 2183
(2011/06/24)
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- Synthesis and reactivity of divinylselenium dichlorides and dibromides
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Regio- and stereospecific electrophilic addition reactions of selenium tetrachloride and selenium tetrabromide to propargyl alcohols are reported. (Z,Z)-Bis(β-chlorovinyl)selenium dichlorides were isolated in high yields, and their reactivity was dependen
- Braverman, Samuel,Pechenick-Azizi, Tatiana,Gottlieb, Hugo E.,Sprecher, Milon
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experimental part
p. 577 - 584
(2011/04/15)
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- Selective indium-mediated 1,2,4-pentatrien-3-ylation of carbonyl compounds for the efficient synthesis of vinyl allenols
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(Chemical Equation Presented) A highly selective synthetic method of functionalized vinyl allenols was developed from the reactions of various carbonyl compounds with organoindium reagent in situ generated from indium and 1-bromopent-4-en-2-yne derivatives. Treatment of vinyl allenols with gold catalyst, dienophile, or indium trihalide produced the functionalized dihydrofuran, cyclohexene, or 2-halo-1,3-diene derivatives in good to excellent yields.
- Park, Jisu,Kim, Sung Hong,Lee, Phil Ho
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supporting information; experimental part
p. 5067 - 5070
(2009/05/31)
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- Preparation of siloxacyclopentene containing 1,3-dienes and their Diels-Alder reactions
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A number of enynyloxy dimethyl and diisopropyl silanes have been prepared and converted into siloxacyclopentene containing 1,3-dienes via intramolecular hydrosilylation of the alkyne functional group. Diels-Alder reactions of these dienes are reported.
- Pidaparthi, Ramakrishna R.,Welker, Mark E.
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p. 7853 - 7856
(2008/03/11)
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- Facile construction of spirocyclopropanated bi-, tri- and tetracyclic skeletons by novel cascades involving intra- and intermolecular heck reactions of 2-bromo-1,6-enynes and bicyclopropylidene
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Acyclic 2-bromo-1,6-enynes 5-R, 9-R and 11-R with bulky substituents at the acetylenic terminus were co-cyclized with the highly strained bicyclopropylidene (12) under palladium catalysis at 80 °C to give the cross-conjugated tetraenes 13-R, 18-R and 19-R in moderate-to-good yields (34-71%). Only the co-cyclization of 5-Ph gave rise to an additional product, which was identified as the 11-membered ring 20. At elevated temperatures (120-140 °C) the initially formed tetraenes underwent 6π- electrocyclization to give spiro[cyclopropane-1,4′-bicylo[4.3.0]-1(6),2- dienes] 21-R, 22-R and 23-R. This novel class of spirocyclopropanated oligocycles is also accessible by a one-pot protocol. The highest yields for both the tetraenes and bicyclo[4.3.0]nonadiene and its heteroanalogues were obtained with bulky substituents at the alkyne terminus of the precursors. Heteroatom-containing precursors 9-R and H-R gave lower yields than their all-carbon analogues 5-R. The acyclic 2-bromo-1,8-dien-6-ynes 28a,b,c upon palladium-catalyzed co-cyclization with bicyclopropylidene (12) at 110 °C gave spirocyclopropanated tricycles 31a,b and 32, respectively, in moderate yields (14, 31 and 32%). These products were formed by two consecutive 6π-electrocyclizations. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Schelper, Michael,De Meijere, Armin
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p. 582 - 592
(2007/10/03)
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- The Intramolecular Enyne Diels-Alder Reaction. Stereoselective Construction of Tricyclic Dioxadienones and Mechanistic Outline
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4-Methylpent-4-en-2-yn-1-ols and 6-hydroxy-2,3-dihydro-6H-pyran-3-ones are condensed in different ways to a series of tricyclic dioxadienones which contain the basic framework of the cadlinolides A mechanism of the intramolecular enyne-ene cycloisomerization and the origin of the resulting type I and type II dienes is proposed.
- Hoffmann, H. M. R.,Krumwiede, D.,Mucha, B.,Oehlerking, H. H.,Prahst, G. W.
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p. 8999 - 9018
(2007/10/02)
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- Base Catalysed Rearrangements involving Ylide Intermediates. Part 7. The Rearrangements of Allyl(pentadienyl)- and Propionyl(pentadienyl)-ammonium Cations. The Sigmatropic Rearrangement.
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The base catalysed rearrangements of the cations (7), (17), (22), and (27) gave the enamines (9), (18), (23), and (28), which on hydrolysis yielded the aldehyde (10), (19), (24), and (29) respectively.The reactions are shown to be concerted sigmatropic rearrangements proceeding via a nine-membered transition state involving 10? electrons.The base catalysed rearrangements of the 3-phenylprop-2-ynyl (pentadienyl) ammonium cations (51), (52), (60), and (61), however yield only the products of , , and sigmatropic rearrangements.
- Laird, Trevor,Ollis, W. David,Sutherland, Ian O.
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p. 2033 - 2048
(2007/10/02)
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