- Photocatalytic carbanion generation from C-H bonds-reductant free Barbier/Grignard-type reactions
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We report a redox-neutral method for the generation of carbanions from benzylic C-H bonds in a photocatalytic Grignard-type reaction. The combination of photo- and hydrogen atom transfer (HAT) catalysis enables the abstraction of a benzylic hydrogen atom, generating a radical intermediate. This radical is reduced in situ by the organic photocatalyst to a carbanion, which is able to react with electrophiles such as aldehydes or ketones, yielding homobenzylic secondary and tertiary alcohols.
- Berger, Anna Lucia,Donabauer, Karsten,K?nig, Burkhard
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p. 10991 - 10996
(2019/12/28)
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- HETEROCYCLIC COMPOUNDS
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The present invention relates to compounds of the general formula (1) wherein the variables are defined as given in the description and claims. The invention further relates to uses of and to, processes and intermediates related to compounds of the general formula (I), wherein Q is wherein the substituents of I, Ia and Ib are as defined in description and claims.
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Page/Page column 76; 79; 80
(2018/07/29)
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- Methyl Group Migration in the Reactions of Alkynyltrialkylborates
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It is shown that the methyl group cannot be used as a cheap, non-migrating group in the reactions of alkynyltrialkylborates with electrophiles.However, trimethylborane can be used as a methylboronating agent for alkynes, given the right choice of solvent, and this may be of use in terpene synthesis.
- Pelter, Andrew,Drake, Robert A.
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p. 4181 - 4184
(2007/10/02)
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- Photochemical Reaction of 1,4-Naphthalenedicarbonitrile with Alkylbenzenes and Bibenzyls
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The photochemical reaction of 1,4-naphthalenedicarbonitrile with some alkylbenzenes and bibenzyls has been examined.A unitary mechanistic picture is formulated on the basis of product study, deuteration experiments, and fluorescence and reaction quantum yield measurements.Proton transfer within the singlet radical ion pair followed by in-cage cycloaddition of the two radicals yields stereoselectively 5,11-methanodibenzo cyclooctene derivatives (8).Reaction of benzyl radicals (formed by protolysis or, for radical cations having no benzylic proton, by C-C bond cleavage) with unprotonated NDN.- leads, again stereoselectively, to 2-benzyl-1,2-dihydronaphtalenes (9).Escape of the donor radical cation and following C-H or C-C bond cleavage leads to a different product, thus, benzyl radicals are trapped by NDN to yield substitution products (11) or recombine.Benzyl cations are trapped by nucleophiles.
- Albini, Angelo,Fasani, Elisa,Mella, Mariella
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p. 4119 - 4125
(2007/10/02)
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- PHOTOCHEMICAL OXIDATION AND DIMERIZATION OF ALKYLBENZENES. SELECTIVE REACTIONS OF THE ALKYL SIDE GROUPS
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Irradiations of alkylbenzene compounds in an oxygen atmosphere result exclusively in oxidation reactions, while in a less oxidative environment dimerization processes predominate.Under all conditions studied, the reactions took place only at one benzyl position.
- Pasternak, Mordechai,Morduchowitz, Abraham
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p. 4275 - 4278
(2007/10/02)
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- PHOTOSUBSTITUTION OF BENZYL HYDROGENS WITH ALCOHOLIC MOIETIES. SELECTIVE FORMATION OF ALKYLBENZENE CARBINOLS
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Irradiations of alkylbenzene compounds with various alcohols in an air atmosphere, resulted in substitution of the benzyl hydrogens with alcoholic moieties in a very selective mode.
- Pasternak, Mordechai,Morduchowitz, Abraham
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p. 3439 - 3442
(2007/10/02)
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- Lithium aluminum hydride-aluminum hydride reduction of sultones
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Lithium aluminum hydride-aluminum hydride reduction of secondary and tertiary (C-O) substituted γ-sultones or α-alkyl-β'-hydroxy γ-sultones yields mercapto alcohols and mercapto diols, respectively, in fair to good yield.These products result from S-O cleavage of the sultone ring.Primary sultones and α-dialkyl-β'-hydroxy γ-sultones give predominantly C-O cleavage to form sulfonic acid derivatives. β-Sultones are much less reactive toward the mixed hydride, and refluxing in dioxane is required for their reduction.
- Smith, Michael B.,Wolinsky, Joseph
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p. 101 - 106
(2007/10/02)
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