- Total Synthesis of Gelsenicine via a Catalyzed Cycloisomerization Strategy
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The first total synthesis of (±)-gelsenicine is reported. The synthetic route is highly efficient (13 steps), featuring (1) a pivotal metal-catalyzed isomerization/rearrangement process that forges the central core of the molecule and (2) two facile C-N bond-forming steps that establish the flanking heterocycles.
- Newcomb, Eric T.,Knutson, Phil C.,Pedersen, Blaine A.,Ferreira, Eric M.
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- Synthesis of 1,3-Diynes via Cadiot-Chodkiewicz Coupling of Volatile, in Situ Generated Bromoalkynes
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A convenient Cadiot-Chodkiewicz protocol that facilitates the use of low molecular weight alkyne coupling partners is described. The method entails an in situ elimination from a dibromoolefin precursor and immediate subjection to copper-catalyzed conditions, circumventing the hazards of volatile brominated alkynes. The scope of this method is described, and the internal 1,3-diyne products are preliminarily evaluated in ruthenium-catalyzed azide-alkyne cycloadditions.
- Knutson, Phil C.,Fredericks, Haleigh E.,Ferreira, Eric M.
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supporting information
p. 6845 - 6849
(2018/10/25)
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- Benzannulation of triynes to generate functionalized arenes by spontaneous incorporation of nucleophiles
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The thermal reaction of ester-tethered 1,3,8-triynes provides novel benzannulation products with concomitant incorporation of a nucleophile. Evidence suggests that this reaction proceeds via an allene-enyne intermediate generated by an Alder-ene reaction in the first step. Depending on the substituent of the alkyne moiety on the allene-enyne intermediate, the subsequent transformation can take one of two different paths, each leading to discrete aromatization products. The benzannulation of a silane-substituted 1,3,8-triynes provides arene products with a nucleophile incorporated onto the newly formed benzene core, whereas an aryl substituent leads to nucleophile trapping at the benzylic carbon atom connected to the aryl substituent. The formation of these two different products results from the involvement of two regioisomeric allene-enyne intermediates.
- Karmakar, Rajdip,Yun, Sang Young,Chen, Jiajia,Xia, Yuanzhi,Lee, Daesung
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supporting information
p. 6582 - 6586
(2015/06/02)
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- PRODUCTION OF 1,1,1-TRIHALOGENO-2-ALKANOLS AND SOME OF THEIR PROPERTIES
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The reaction of acyclic and carbocyclic carbonyl compounds with haloforms was studied in liquid ammonia and dimethylformamide in the presence of basic catalysts (t-BuOK, KOH).As a result of the reaction 1,1,1-trihalogeno-2-alkanols were obtained.They were used for the synthesis of 1,1,1-trihalogeno-2-methoxyalkanes, 1,1-dibromoalkenes, 1,1-dichloro-2-methoxyalkenes, and alkyl mono- and dichloromethyl ketones.
- Bal'on, Ya. G.,Shul'man, M. D.,Vakulenko, L. I.
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p. 1231 - 1237
(2007/10/02)
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- Preparation of epoxides
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This invention is a process for the preparation of an epoxide which comprises contacting a 2-haloalkyl or 2,3-dihaloalkyl carbonate, bis(2-haloalkyl- or 2,3-dihaloalkyl)carbonate, or 2-haloalkyl or 2,3-dihaloalkyl ester dissolved in a water-miscible alcohol with a sufficient amount of an aqueous solution of an alkali metal or alkaline earth metal hydroxide to provide at least one equivalent of alkali metal or alkaline earth metal hydroxide per equivalent of ester or carbonate, at a temperature of between about 0° C. and 70° C. under conditions such that an epoxide is prepared.
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- Reactions with Phosphinealkylenes, XXXIX. - New Methods for the Preparation of 1-Bromoacetylenes and Enynes
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1,1-Dibromoolefins 4 are obtained in good yield from the reaction of aldehydes 1 with triphenylphosphane (2) and carbon tetrabromide (3).Reaction of 4 with three moles of methylene(triphenyl)phosphorane (8) leads to the propargylidene(triphenyl)phosphoranes 11 which react with aldehydes to give the enynes 13.The ylides 11 can also prepared via the reaction of bromoacetylenes 7, which can be obtained from 4, with two moles of 8.This reaction sequence allows the synthesis of new retinoids with enyne structures from retinal.
- Bestmann, Hans Juergen,Frey, Herbert
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p. 2061 - 2071
(2007/10/02)
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