- Enantioselective Intermolecular Pd-Catalyzed Hydroalkylation of Acyclic 1,3-Dienes with Activated Pronucleophiles
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We report a highly enantioselective Pd-PHOX-catalyzed intermolecular hydroalkylation of acyclic 1,3-dienes. Meldrum's acid derivatives and other activated C-pronucleophiles, such as β-diketones and malononitriles, react with a variety of aryl- and alkyl-substituted dienes in ≤20 h at room temperature. The coupled products, obtained in up to 96% yield and 97.5:2.5 er, are easily transformed into useful chemical building blocks for downstream synthesis.
- Adamson, Nathan J.,Wilbur, Katherine C. E.,Malcolmson, Steven J.
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supporting information
p. 2761 - 2764
(2018/03/06)
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- Asymmetric 1,4-dihydroxylation of 1,3-dienes by catalytic enantioselective diboration
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(Chemical Equation Presented) Asymmetric 1,4-dihydroxylations of 1,3-dienes, and other transformations, are initiated by the Pt-catalyzed enantioselective addition of bis(pinacolato)diboron (B2(pin) 2) to conjugated dienes. The studies reported in this communication suggest that both cyclic and acyclic substrates will participate in this reaction; however, dienes which are unable to adopt the S-cis conformation are unreactive. For most substrates, 1,4-addition is the predominant pathway. In addition to oxidation to the derived 2-buten-1,4-diol, stereoselective carbonyl allylation with the intermediate bis(boronate) ester is also described.
- Burks, Heather E.,Kliman, Laura T.,Morken, James P.
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supporting information; scheme or table
p. 9134 - 9135
(2009/12/05)
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- Stereoselective synthesis of homochiral substituted tetrahydrothiophenes by electrophile-promoted thioetherification
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In this paper we study the electrophile-promoted cyclization of 2-sulfanyl-4-penten-1-ol and 1-sulfanyl-4-penten-2-ol derivatives as a way of preparing cyclic sulfides. The reaction is completely chemoselective and always proceeds by activation of the sulfur centre. The reaction of 2-sulfanyl-4-penten-1-ol derivatives proceeds by a 5-endo mode. Unsaturated thiol 6 undergoes iodine-promoted cyclothioetherification to give the tetrahydrothiophene 9 in moderate yields and with excellent regio- and stereoselectivity. However, when the reaction starts from the benzyl sulfide 7, a diastereomeric mixture of 9 and 10 is obtained in good yields. Selenium-promoted cyclization of unsaturated thioacetate 5 provides the selenyltetrahydrothiophene 12 or the sulfanyl acetate 13, depending on the selenium reagent used. On the other hand, electrophile-induced cyclization of 1-sulfanyl-4-penten-2-ol derivatives 23-25 depends on the electrophile used. Iodothioetherification of benzyl sulfide 25 followed by oxidation affords unsaturated sulfone 26 as a result of 6-endo-cyclization, dehydroiodination and oxidation. In contrast, selenothiocyclization of 24 with PhSeX results in the formation of the 5-exo tetrahydrothiophenes 29/30 and/or 31/32. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Jana, Gourhari,Viso, Antonio,Diaz, Yolanda,Castillon, Sergio
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p. 209 - 216
(2007/10/03)
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- Intramolecular Diels-Alder Reactions of Silyl Acetal-tethered Trienes
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The synthesis and intramolecular Diels-Alder reactions of a series of silyl acetal-tethered trienes 4-9 are described.The cycloadditions show complete regioselectivity, and in all but one case give exclusively cis-fused bicyclic products.The selectivities
- Ainsworth, Peter J.,Craig, Donald,Reader, John C.,Slawin, Alexandra M. Z.,White, Andrew J. P.,Williams, Dawid J.
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p. 11601 - 11622
(2007/10/02)
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