Convenient synthesis of trans olefins from alkynes via hydroboration-cyanohalogenation

Zweifel, George; Fisher, Richard P.; Snow, John T.; Whitney, Charles C.

doi:10.1021/ja00773a059

Cited by 78 publications

(18 citation statements)

References 3 publications

(4 reference statements)

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“…[81][82][83] These examples showed that aryl and alkylboranes can undergo arylation processes by treatment with electronrich aryllithiums (e.g., 2-lithiofuran, 2-lithiothiophene) followed by electrophilic trapping (Scheme 21). The mechanism of these coupling reactions is analogous to the Zweifel olefination reaction [84] and comprises a sequence of electrophilic aromatic substitution, 1,2-metallate rearrangement, and elimination [85,86] from the in situ formed aryl-substituted boronate complex. A more detailed mechanistic discussion is presented later.…”

Section: Pioneering Workmentioning

confidence: 99%

Stereospecific Couplings of Secondary and Tertiary Boronic Esters

2014

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Section: Pioneering Workmentioning

confidence: 99%

Stereospecific Couplings of Secondary and Tertiary Boronic Esters

2014

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“…Considering the stereochemical features of this process, a syn elimination (giving the E ‐alkene) should be possible if the interaction between the β‐halogen and boron of the β‐haloboron intermediate could be enhanced. Indeed, Zweifel demonstrated that syn elimination was favoured if a strong electron‐withdrawing group (CN) was introduced on boron, which allowed coordination of the bromide to boron in intermediate 10 and resulted in the formation of E ‐olefins 11 (Scheme c) …”

Section: Stereospecific 12‐migration Of Alkenyl Boronates Induced Bymentioning

confidence: 99%

Stereospecific 1,2‐Migrations of Boronate Complexes Induced by Electrophiles

et al. 2020

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The stereospecific 1,2‐migration of boronate complexes is one of the most representative reactions in boron chemistry. This process has been used extensively to develop powerful methods for asymmetric synthesis, with applications spanning from pharmaceuticals to natural products. Typically, 1,2‐migration of boronate complexes is driven by displacement of an α‐leaving group, oxidation of an α‐boryl radical, or electrophilic activation of an alkenyl boronate complex. The aim of this article is to summarize the recent advances in the rapidly expanding field of electrophile‐induced stereospecific 1,2‐migration of groups from boron to sp2 and sp3 carbon centers. It will be shown that three different conceptual approaches can be utilized to enable the 1,2‐migration of boronate complexes: stereospecific Zweifel‐type reactions, catalytic conjunctive coupling reactions, and transition metal‐free sp2–sp3 couplings. A discussion of the reaction scope, mechanistic insights, and synthetic applications of the work described is also presented.

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“…9 However, Zweifel and co-workers subsequently reported an elegant strategy for the complementary synthesis of E-alkenes (Scheme 3). 10 This transformation was achieved by reacting dialkyl vinyl borane 5 with cyanogen bromide under base-free conditions. Following stereospecific bromination, a boranecarbonitrile intermediate 8, was formed, a species that was sufficiently electrophilic to undergo syn elimination.…”

Section: Zweifel Olefination Of Vinyl Boranesmentioning

confidence: 99%

50 Years of Zweifel Olefination: A Transition-Metal-Free Coupling

2017

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The Zweifel olefination is a powerful method for the stereoselective synthesis of alkenes. The reaction proceeds in the absence of a transition-metal catalyst, instead taking place by iodination of vinyl boronate complexes. Pioneering studies into this reaction were reported in 1967 and this short review summarizes developments in the field over the past 50 years. An account of how the Zweifel olefination was modified to enable the coupling of robust and air-stable boronic esters is presented followed by a summary of current state of the art developments in the field, including stereodivergent olefination and alkynylation. Finally, selected applications of the Zweifel olefination in targetoriented synthesis are reviewed.

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Convenient synthesis of trans olefins from alkynes via hydroboration-cyanohalogenation

Cited by 78 publications

References 3 publications

Stereospecific Couplings of Secondary and Tertiary Boronic Esters

Stereospecific Couplings of Secondary and Tertiary Boronic Esters

Stereospecific 1,2‐Migrations of Boronate Complexes Induced by Electrophiles

50 Years of Zweifel Olefination: A Transition-Metal-Free Coupling

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