- Mild and phosphine-free iron-catalyzed cross-coupling of nonactivated secondary alkyl halides with alkynyl grignard reagents
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A simple protocol for iron-catalyzed cross-coupling of nonactivated secondary alkyl bromides and iodides with alkynyl Grignard reagents at room temperature has been developed. A wide range of secondary alkyl halides and terminal alkynes are tolerated to a
- Cheung, Chi Wai,Ren, Peng,Hu, Xile
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supporting information
p. 2566 - 2569
(2014/05/20)
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- A Novel Transformation of Esters to Alkynes with 1-Substituted Benzotriazoles
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Reactions of lithio benzotriazol-1-yl derivatives 2, 11, and 25 with aromatic and aliphatic esters 3, 12, and 26 gave α-(benzotriazol-l-yl) ketones 4, 13, and 27, respectively, in high yields. Alternatively, α-(benzotriazol-l-yl) ketones 22 can be accessed by the reaction of α-(benzotriazol-1-yl) esters 20 with Grignard reagents. Condensation of 4, 13, 22, and 27 with (p-toluenesulfonyl)hydrazine provided p-tosylhydrazones 5, 14, 21, and 28. Treatment of hydrazones 5, 21, and 28 with n-butyllithium in diethyl ether resulted in the elimination of the tosyl group, dinitrogen, and benzotriazolyl group to afford the corresponding acetylenes 9, 23, and 29 in good yields. When α-(benzotriazol-l-yl) 1-α-phenoxy hydrazones 14 were treated with methyllithium, n-butyllithium, or phenyllithium, alkynes 18 were obtained, in which phenoxy groups were replaced by the lithium reagents.
- Katritzky, Alan R.,Wang, Jin,Karodia, Nazira,Li, Jianqing
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p. 4142 - 4147
(2007/10/03)
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- Preparation of Allenic Sulfones and Allenes from the Selenosulfonation of Acetylenes
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β-(Phenylseleno)vinyl sulfones 2 are readily obtained from the free-radical selenosulfonation of acetylenes.Compounds 2 isomerize to allyl sulfones 4 under base-catalyzed conditions in nearly quantitative yield, with high stereoselectivity favoring the Z configuration.Allyl sulfones 4 afford generally high yields of allenic sulfones 1 when subjected to oxidation with m-chloroperbenzoic acid or tert-butyl hydroperoxide, followed by selenoxide syn-elimination.The sulfone-stabilized anion intermediates in the isomerizations of 2 to 4 can be alkylated, deuterated,or silylated in the α-position prior to oxidation, providing allenic sulfones with an additional α-substituent.In some cases, spontaneous elimination of the phenylseleno group occurred, producing the allenic sulfone without the need for an oxidation step.Desulfonylation of allyl sulfones 4f, 4c, and 25 with sodium amalgam afforded vinyl selenides that were converted to allenes in moderate to good yields by oxidation-elimination.The copper catalyzed coupling of allyl sulfones 4 with Grignard reagents comprises an alternative route to vinyl selenide precursors of allenes.These procedures permit the synthesis of various α- and γ-substituted allenic sulfones and allenes from acetylenes.
- Back, Thomas G.,Krishna, M. Vijaya,Muralidharan, K. Raman
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p. 4146 - 4153
(2007/10/02)
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