Phenyl-Substituted Vinylstannanes: Synthesis and Reactivity in Electrophilic Substitution Reactions

Cochran, John C.; Phillips, Harmony K.; Tom, Samson; Hurd, Alexander R.; Bronk, Brian S.

doi:10.1021/om00015a031

Cited by 18 publications

(22 citation statements)

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“…2-Bromo-1,1-diphenylethen (2) was synthesised by the reaction of 1,1-diphenylethene (1) with bromine in CCl 4 . 2 The crude product was dissolved in CH 2 Cl 2 , washed with 10% aq NaHCO 3 and purified by two consecutive distillations under N 2 in 80% yield as a solid with spectroscopic data identical to those reported in the literature (IR, 17 1 H NMR, 18 13 C NMR 19 ). Bp 100-104°C/0.1 mbar; mp 40-41°C (Lit.…”

mentioning

confidence: 77%

Efficient Mono- and Dilithiation of 2-Bromo-1,1-diphenylethene with n-Butyllithium/Tetramethylethylenediamine

Korneev¹,

Kaufmann²

2002

Synthesis

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Lithiation of 2-bromo-1,1-diphenylethene (2) with n-butyllithium or tert-butyllithium/tetramethylethylenediamine (TME-DA) in pentane at -100°C effects a halogen-lithium exchange to give 2-lithio-1,1-diphenylethene (3) exclusively, which reacts with electrophiles to provide 2-substituted-1,1-diphenylethenes 5-8 in high yields. Further lithiation of the monolithium derivative 3 with n-butyllithium/TMEDA results in the direct ortho-lithiation of Z-located phenyl ring to give dilithium derivative 9, which forms disubstituted ethenes 11-13 or heterocycles 15-17 on treatment with electrophiles. tert-Butyllithium/TMEDA is ineffective for the second lithiation step.Two different reaction pathways are known for the lithiation of 2-halo-1,1-diphenylethenes. 2,3 The first path includes proton removal (Scheme 1, route a) under the action of a strong base with the formation of 1-halo-1-lithioethene A. In the case of the chloro derivative (X = Cl) this intermediate is sufficiently stable at low temperature (-100 to -85°C) to react with electrophiles, like CO 2 or Br 2 , resulting in the formation of 1-substituted 1-halo-2,2-diphenylethenes in moderate yields. 4-6 At higher temperature or in the cases of bromo and iodo derivatives (X = Br, I), which are significantly more reactive, A readily rearranges into diarylacetylene B. 5-9 This classical example of the anionic rearrangement was discovered in 1894 10 and recognised as a very suitable way for the synthesis of diarylacetylenes. 7,8 Scheme 1 X = Cl, Br, I.The second possibility is halogen-metal exchange (Scheme 1, route b) to give the vinyllithium C. 5,11,12 This way is more distinctive for bromo-and iodo-derivatives (X = Br, I) and provides a versatile synthetic tool for the preparation of 2-substituted 1,1-diarylethene D. Unfortunately, this halogen-metal exchange is accompanied usually by the formation of acetylenes that reduce the synthetic scope of the reaction. 12,13 We wish to report here improved conditions for selective and efficient halogen-lithium exchange in 2-bromo-1,1-diphenylethene (2) in the presence of TMEDA, which result in the formation of 1,1-diphenylethylene derivatives on treatment of the intermediate vinyllithium compound 3 with electrophiles. Alternatively, the vinyllithium compound 3 can undergo further lithiation of the phenyl ring.Lithiation of 2-bromo-1,1-diphenylethene (2) with 3 equivalents of n-BuLi or t-BuLi in pentane in the presence of 3 equivalents of TMEDA results in complete halogenlithium exchange at -100°C already within 20 minutes (Scheme 2). Product distribution at different temperatures were investigated by treatment of the reaction mixture with iodine (Table 1). At -100°C the iodide 5 together with a small amount of ethene 1 were identified as the only products along with traces of the starting bromide 2 (<2%). When the reaction was allowed to warm to 0°C during 1 h, further deactivation of the lithium derivative 3 to ethene 1 was observed. No rearranged tolane 4 was detected not only after instant warming up, but also on keeping th...

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confidence: 77%

Efficient Mono- and Dilithiation of 2-Bromo-1,1-diphenylethene with n-Butyllithium/Tetramethylethylenediamine

Korneev¹,

Kaufmann²

2002

Synthesis

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“…A number of groups have studied the hydrostannation of alkynyl esters. 23,[90][91][92][93][94][95] As shown in the following representative examples, electronic effects prevail in controlling the hydrostannation regioselectivity, and steric considerations play a lesser role (Scheme 47). 90 In contrast to alkynyl esters, alkynyl ketones are more challenging substrates for selective hydrostannation because of unwanted protodestannylation.…”

Section: Alkynes With Electron-withdrawing Substituentsmentioning

confidence: 99%

“…Conjugated internal alkynes are a generally reliable substrate class under palladium catalysis, and their hydrostannation shows good regioselectivity for the α-addition product (Scheme ). A number of groups have studied the hydrostannation of alkynyl esters. ,− As shown in the following representative examples, electronic effects prevail in controlling the hydrostannation regioselectivity, and steric considerations play a lesser role (Scheme ). In contrast to alkynyl esters, alkynyl ketones are more challenging substrates for selective hydrostannation because of unwanted protodestannylation.…”

Section: Scope and Limitationsmentioning

confidence: 99%

Hydrostannation of Alkynes

2019

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In this review, we present an overview of hydrostannation of alkynes until the end of 2018. Mechanism of the tin hydride addition on a triple bond is discussed at the beginning of this review in the presence of metal catalysts as Pd, Ru-based complexes, Lewis acids and under radical conditions. Then, stereoselectivity as well as regioselectivity aspects of tin hydride addition on the carbon triple bond is discussed using metal-catalysis, radical conditions or Lewis acids. In each of these items, the reactions will be studied for terminal alkynes and then, for internal alkynes. Applications of hydrostannation of alkynes using metal-catalysis is presented in a variety of total syntheses with Pd, Mo, Rh and Ru-complexes to provide highly functionalized vinyl stannanes derivatives as key-intermediates. Comparison with other methods providing vinyl stannanes using metallostannation followed by protonation is presented before the last section dealing with a summary of classical experimental conditions used to achieve the hydrostannation of alkynes.

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“…Regio‐ and stereoisomeric vinyl stannanes have often been synthesized by the reaction of organotin hydrides with alkynes and have further been used in cross‐coupling and substitution reactions. The stereo‐ and regioselectivities in the hydrostannation of alkynes depend on the reaction conditions, nature and bulk of substituents on the alkyne, polarization of the alkyne′s triple bond and presence of properly oriented heteroatoms that can chelate to the metal during the reaction . According to Alami et al .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Stannyl‐Substituted d‐Glucal Derivatives via Palladium‐Catalyzed Regioselective Hydrostannation and Their Synthetic Applications

et al. 2016

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Stannyl derivatives of 2-alkenyl acetylated D-glucals have been synthesized via palladium-catalyzed regioselective hydrostannation in good yields under mild reaction conditions. Factors affecting the regioselectivity of hydrostannation including chelation by the neighbouring acetyl-oxygen and the electronic effect of the substituent R on alkyne have been evaluated. The synthetic applications of these stannyl derivatives of D-glucal are shown by performing Stille and Sonogashira cross-coupling reactions to obtain a library of substituted 2-alkenyl derivatives of D-glucal.

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Phenyl-Substituted Vinylstannanes: Synthesis and Reactivity in Electrophilic Substitution Reactions

Cited by 18 publications

References 0 publications

Efficient Mono- and Dilithiation of 2-Bromo-1,1-diphenylethene with n-Butyllithium/Tetramethylethylenediamine

Efficient Mono- and Dilithiation of 2-Bromo-1,1-diphenylethene with n-Butyllithium/Tetramethylethylenediamine

Hydrostannation of Alkynes

Synthesis of Stannyl‐Substituted d‐Glucal Derivatives via Palladium‐Catalyzed Regioselective Hydrostannation and Their Synthetic Applications

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