- Regio- and Diastereoselective Synthesis of Dihydropyrans and Pyranopyrans via Oxonium-Ene Reaction of β-Allenols and Aldehydes
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Bismuth trifluoromethanesulfonate can be efficiently used for the preparation of dihydropyrans from β-allenols and aldehydes by oxonium-ene reaction in good yields. The reaction is highly regioselective. On the other hand, the same reaction with trimethyl
- Devi, Ngangbam Renubala,Sultana, Sabera,Borah, Madhurjya,Saikia, Anil K.
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- Regioselective Rh-Catalyzed Hydroformylation of 1,1,3-Trisubstituted Allenes Using BisDiazaPhos Ligand
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The efficient hydroformylation of 1,1,3-trisubstituted allenes is accomplished with low loadings of a Rh catalyst supported by a BisDiazaPhos (BDP) ligand. The ligand identity is key to achieving high regioselectivity, while the mild reaction conditions m
- Eshon, Josephine,Landis, Clark R.,Schomaker, Jennifer M.
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p. 9270 - 9278
(2017/09/22)
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- Selective Palladium-Catalyzed Allenic C?H Bond Oxidation for the Synthesis of [3]Dendralenes
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A highly selective palladium-catalyzed allenic C?H bond oxidation was developed, and it provides a novel and straightforward synthesis of [3]dendralene derivatives. A variety of [3]dendralenes with diverse substitution patterns are accessible with good efficiency and high stereoselectivity. The reaction tolerates a broad substrate scope containing various functional groups on the allene moiety, including ketone, aldehyde, ester, and phenyl groups. Also, a wide range of olefins with both electron-donating and electron-withdrawing aryls, acrylate, sulfone, and phosphonate groups are tolerated.
- Qiu, Youai,Posevins, Daniels,B?ckvall, Jan-E.
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supporting information
p. 13112 - 13116
(2017/09/28)
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- Diastereoselective synthesis of pyrrolidine derivatives via a one-pot nitro-Mannich/hydroamination cascade using base and gold catalysis
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An efficient one-pot nitro-Mannich/hydroamination cascade reaction for the synthesis of substituted pyrrolidines bearing three stereocentres is reported. Proceeding under the control of a combination of base and gold(i) catalysts, the cascade reaction aff
- ?uri?, Andrej,Barber, David M.,Sanganee, Hitesh J.,Dixon, Darren J.
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supporting information
p. 2777 - 2779
(2013/04/23)
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- TBAF-mediated aldol reaction of β-allenoates: Regio- and stereoselective synthesis of (2E,4E)-4-carbinol alkadienoates
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(Chemical Equation Presented) The aldol reaction of β-allenoate with use of a commercial THF solution of tetrabutylammonium fluoride (TBAF) yielded polyfunctionalized (2E,4E)-4-carbinol alkadienoate - a valuable building block - in highly regio- and stereoselective fashion.
- Aponte, Jose C.,Hammond, Gerald B.,Xu, Bo
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supporting information; experimental part
p. 4623 - 4625
(2009/09/08)
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- Highly stereoselective lodolactonization of 4,5-allenoic acids - An efficient synthesis of 5-(1′-Iodo-1′(Z)-alkenyl)-4,5-dihydro-2(3H)- furanones
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In this paper, it is reported that the efficient iodolactonization of 4,5-allenoic acid with I2 in cyclohexane in the presence or absence of K2CO3 afforded 5-(1′-iodo-1′(Z)-alkenyl)-4, 5-dihydro-2(3H)-furanones highly stereo-selectively. However, the reaction of axially optically active 4,5-allenoic acids (R)-(-)-5a and (R)-(-)-5b with I2 afforded the corresponding products with a serious loss of chirality. This problem was solved by conducting the iodolactonization with N-iodosuccinimide in CH2Cl2 in the presence of Cs 2CO3; however, the Z/E selectivity is somewhat lower. The pure optically active Z products were prepared by subsequent kinetic resolution with Sonogashira coupling. The reaction of thesubstrates with a substituent at the 3-position of the starting 4,5-allenoic acids afforded the trans-4,5-disubstituted γ-butyrolactones as the only products. The reaction of the 4,5-allenoic acids (S)-(+)-11, (R)-(-)-11, and (S)-(+)-lm with a center chirality at the 3-position afforded the trans products with very high enantiopurity and up to 98:2 Z/E selectivity regardless of the axial chirality of the allene moiety.
- Jiang, Xinpeng,Fu, Chunling,Ma, Shengming
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supporting information; experimental part
p. 9656 - 9664
(2009/12/01)
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- Ruthenium-catalyzed two-component addition to form 1,3-dienes: Optimization, scope, applications, and mechanism
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A two component coupling of an allene and an activated olefin to form 1,3-dienes has been developed. The requisite allenes are synthesized either from terminal alkynes by a one carbon homologation using copper(I) iodide, paraformaldehyde, and diisopropyla
- Trost,Pinkerton,Seidel
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p. 12466 - 12476
(2007/10/03)
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