Diphenylhydantil

Dudley, Kenneth H.; Bius, Daniel L.

doi:10.1021/jo01256a083

Cited by 5 publications

(3 citation statements)

References 1 publication

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“…The resulting radicals can dimerize if their half-life is sufficiently long, or undergo fragmentation or other reactions characteristic of radicals. Carbanions with a high tendency to become oxidized by SET are deprotonated nitroalkanes [508,509] and carbanions substituted with both electron-donating and electron-withdrawing groups [510][511][512][513] (Scheme 5.69). Potential oxidants can be air, the solvent, the carbanion itself (disproportionation), or an added oxidant or electrophile.…”

Section: 46mentioning

confidence: 99%

The Alkylation of Carbanions

Dörwald

2004

Side Reactions in Organic Synthesis

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The deprotonation of organic compounds by strong, non-nucleophilic bases followed by C-alkylation with a suitable electrophile has become one of the most predictable and straightforward methods for formation of C-C bonds. The popularity of this chemistry is also a consequence of the often-seen close resemblance of feasible structural modifications by a deprotonation/alkylation strategy to an unsophisticated retrosynthetic analysis of a given target compound. Other reactions, which involve, for instance, substantial rearrangement of the carbon framework (e.g. Cope rearrangement, fragmentations, ring contractions or enlargements) are usually more difficult to take into account during retrosynthetic analysis.LDA and related, sterically hindered, lithium dialkylamides, first investigated by Levine [1], have completely replaced the more nucleophilic sodium amide, which had been the base of choice for many years [2]. Because the reactivity of an organometallic compound depends to a large extent on its state of aggregation (i.e. on the solvent and on additives) and on the metal, transmetalation of the lithiated intermediates and the choice of different solvents and additives emerged as powerful strategies for fine-tuning the reactivity of these valuable nucleophiles.In this chapter the alkylation of carbanions with simple carbon electrophiles will be discussed, with special emphasis on the structure-reactivity relationship of the carbanion and on side reactions. In this context the term "carbanion" refers to an intermediate prepared by in-situ deprotonation of an organic compound, followed by optional cation exchange (transmetalation), which tends to be alkylated at carbon by soft electrophiles such as MeI or PhCHO. This type of reactivity is characteristic of enolates with an ionic M-O bond or for organometallic compounds with a strongly polarized or ionic M-C bond, M typically being an alkali metal, Mg, Cu, or Zn. Carbanions can, alternatively, also be prepared by halogen-metal exchange [3-8], sulfoxide-or sulfone-metal exchange [9-13], or by transmetalation of stannanes. The most suitable reagents for performing such metalating exchange reactions are organometallic compounds with a metal-bound secondary or tertiary alkyl group, such as tBuLi, sBuLi, iPr 2 Zn [14, 15], or iPrMgHal [6]. These reagents are thermodynamically less stable than organometallic compounds with primary alkyl 5 146 Scheme 5.1. Approximate relative rates of proton transfer in water at thermoneutrality (DpK a = 0) [35, 39, 51]. 147 Scheme 5.2. The effect of fluorine on the acidity of organic compounds [24, 62-65]. 148 Scheme 5.3. Dependence of the reactivity of carbanions on their basicity [68, 72-74]. Regioselectivity of Deprotonations and AlkylationsThe organic chemist is occasionally confronted with the problem that a compound has several differrent X-H groups of similar pK a . If only one of these is to be alkylated, one option would be to perform a regioselective deprotonation. This can sometimes be achieved by exploiting small differences be...

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Section: 46mentioning

confidence: 99%

The Alkylation of Carbanions

Dörwald

2004

Side Reactions in Organic Synthesis

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“…The formation of the reagent dimer X V l l l when there was a n excess of p-nitrolxnzyl bromide could have been caused by the rearrangement of the dialkyl derivative I Scheme I-Proposed mechanism for the formation of 3, requires that the benzylic protons be acidic, as would be the case in the p-nitro derivative but not the metn-isomer. Such a mechanism is supported by the fact that alkylation of I11 with m-nitrobenzyl bromide under similar conditions did not produce the analogous 3,3'-dinitrobibenzyl.…”

Section: Experimental'mentioning

confidence: 99%

Alkylation Reactions of Hydantoins and Succinimides

Yung

Forrest

Gilroy

et al. 1973

Journal of Pharmaceutical Sciences

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“…[8] It can be used in monotherapy or associate with other cytotoxic drugs, such as taxol against prostate and ovaries tumors; [9] b-lapachone combined with curcumin and topotecan was also efficient and selective inhibitors of HIV-1 LTR-directed gene expression. [10] Lapachones derivatives can be obtained from the cyclization of lapachol 3 or isolapachol 4 (Scheme 1), the cyclization can be catalyzed by inorganic acids (i. e. HCl or H 2 SO 4 ), [11] 2,3dichloro-5,6-dicyanobenzoquinone (DDQ), [12] Lewis acids (i. e. AlCl 3 , BF 3 , NbCl 5 ,…) [13] and ArSeSeAr or ArSSAr/I 2 . [14] When diselenides or disulfides compounds were used in the lapachol cyclization chalcogen-containing lapachone were reached, with the chalcogen atom attached at C-3.…”

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Synthesis of Lapachone Derivates via Ionic Liquid‐Mediated Tandem Knoevenagel/Diels‐Alder Reaction

et al. 2017

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The use of ionic liquid (IL) in Tandem Knoevenagel/Diels‐Alder Reaction is an optimization method for one‐pot procedures, providing great results under mild conditions. In this paper, four new Lapachone derivatives were obtained using lawsone as substrate. The effects of the catalytic use of ionic liquids and catalysts in organometallic systems were evaluated. Several lapachone derivatives were obtained good to excellent yields.

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Diphenylhydantil

Cited by 5 publications

References 1 publication

The Alkylation of Carbanions

The Alkylation of Carbanions

Alkylation Reactions of Hydantoins and Succinimides

Synthesis of Lapachone Derivates via Ionic Liquid‐Mediated Tandem Knoevenagel/Diels‐Alder Reaction

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