Chlorsubstituierte Vinyllithium‐Verbindungen

Köbrich, Gert; Flory, Klaus

doi:10.1002/cber.19660990602

Cited by 66 publications

(27 citation statements)

References 23 publications

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“…Similarly, Köbrich and Flory metalated 1 with n-butyllithium and treated the so generated vinyl lithium intermediate 26 with carbon dioxide to afford trichloroacrylic acid (27) (Scheme 5). 25 Scheme 2 Addition reaction of hydroxy arenes and heteroarenes 19a-l to 2-bromo-1,1-difluoroethene (4). Based on the results of Köbrich and Flory, Tarrant prepared fluorine-containing vinyllithium reagents using 28.…”

Section: Addition Reactionsmentioning

confidence: 99%

“…(Z)-1-Bromo-1,2-dichloroethene (18) was prepared in 1966 by Köbrich and Flory by lithiation of (E)-1,2dichloroethene (17), followed by treatment with bromine (Scheme 1d). 25 The following sections will focus on the chemistry of trihaloethenes, in particular TCE (1). Their functionalization via addition, elimination and transition metal-catalyzed reactions is presented, as well as their application in the synthesis of natural products.…”

Section: Introductionmentioning

confidence: 99%

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Trihaloethenes as versatile building blocks for organic synthesis

Grossmann

Magauer

2016

Org. Biomol. Chem.

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Section: Addition Reactionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Trihaloethenes as versatile building blocks for organic synthesis

Grossmann

Magauer

2016

Org. Biomol. Chem.

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“…These processes can, however, often be suppressed by keeping the reaction temperature low, and numerous examples of the a-lithiation and alkylation of vinyl halides have been reported [327,438] (Scheme 5.51). The solvent mixture of the first example is required because pure THF (mp -108 C) becomes too viscous at these low temperatures [440]. The examples in Scheme 5.51 illustrate the reaction conditions required for such conversions.…”

Section: A-eliminationmentioning

confidence: 99%

“…The rate of elimination will increase with increasing reactivity of the carbanion and with increasing ability of the leaving group to act as such [444]. Generation and alkylation of a-halo or a-(tosyloxy)vinyllithium compounds [332,[440][441][442]. 184 Scheme 5.51.…”

Section: B-eliminationmentioning

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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“…The reaction of (E)-1,2-dichloroethene with a twofold amount of alkyllithium, at 0°C, leads to lithium chloroacetylide (6). This intermediate reacts with carbon dioxide to afford 1-chloropropiolic acid 32,33 or with tri-n-butylborane to give after rearrangement symmetrical alkynes 34 (Scheme 10).…”

Section: Alkynesmentioning

confidence: 99%

1,2-Dihalogenalkenes: Useful Linchpins to Unsaturated Compounds via Palladium or Nickel Catalysis

Alami¹,

Peyrat²,

Brion³

2000

Synthesis

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The reactivity and synthetic applications of 1,2-dihalogenoalkenes towards the construction of unsaturated compounds are reviewed, covering the literature from 1956 to 2000. 1 Introduction 2 1,2-Dichloroethenes 2.1 Alkenes and 1-Chloroalkenes 2.2 Alkynes 2.3 Chloroenynes and Enediynes 2.4 Chlorodienes and Chlorotrienes 2.5 Polyenes 3 1,2-Dibromoethenes 4 Polyhalogenoalkenes 4.1 Alkenes and Halogenoalkenes 4.2 Alkynes and 1,3-Diynes 4.3 Enynes and Dienes 5 Conclusion

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Chlorsubstituierte Vinyllithium‐Verbindungen

Cited by 66 publications

References 23 publications

Trihaloethenes as versatile building blocks for organic synthesis

Trihaloethenes as versatile building blocks for organic synthesis

The Alkylation of Carbanions

1,2-Dihalogenalkenes: Useful Linchpins to Unsaturated Compounds via Palladium or Nickel Catalysis

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