Tin, Silicon and Related Reducing Agents

Chatgilialoglu, Chryssostomos

doi:10.1002/9783527618293.ch3

Cited by 15 publications

(7 citation statements)

References 89 publications

(50 reference statements)

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“…The effect of the substituent position was also evaluated using metaor ortho-substituted rings. Little difference in yields were observed for both meta- (15)(16)(17)(18) and ortho-substituted (18,19,29 and 32) aryl halides in comparison with their para-functionalised counterparts. Other aryl iodides like 1-and 2-iodonapthalenes, 2-iodo-pyrazine, 4-iodo-pyridine and 2-iodothiophenes were also suitable substrates for the transformation giving 21-26 in moderate to good yields.…”

Section: Substrate Scopementioning

confidence: 96%

“…An alternative approach for aryl radical generation involves the homolytic sp 2 C-X bond cleavage via halogen-atom transfer (XAT) which has historically been achieved using tin radicals. 18 Strategies based on silicon radicals 19 have circumvented the use of toxic tin hydrides and more recently have been successfully exploited in metallaphotoredox manifolds, retrieving an increasingly renewed interest. 20 We have recently demonstrated that generating a-aminoalkyl radicals from alkylamines (A / B) under photoredox catalysis represents an effective gateway to access alkyl and aryl radicals from the corresponding halides (Scheme 1B).…”

Section: Introductionmentioning

confidence: 99%

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A case of chain propagation: α-aminoalkyl radicals as initiators for aryl radical chemistry

et al. 2020

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Section: Substrate Scopementioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

A case of chain propagation: α-aminoalkyl radicals as initiators for aryl radical chemistry

et al. 2020

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“…However, like other organotin compounds, it is toxic, and difficult to remove completely from the desired products. In the late 1980s, tris(trimethylsilyl)silane ((TMS) 3 SiH) and subsequently in the early 1990s ethyl piperidium hypophosphite (EPHP; the chain carrier in this case is H 2 PO 2 − ) were introduced as alternative reagents to tin hydride. However, (TMS) 3 SiH is expensive and not easy to prepare, while EPHP needs to be used in large excess with high concentrations of radical initiator.…”

Section: Introductionmentioning

confidence: 99%

Effects of Chemical Structure on the Thermodynamic Efficiency of Radical Chain Carriers for Organic Synthesis

2011

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The chain carrier index (CCI), defined as the ratio of the bond dissociation free energies (BDFE) of corresponding chain carrier halides and hydrides, is proposed as a measure of the thermodynamic efficiency of chain carriers for radical dehalogenation. The larger this value is relative to the corresponding value of the organic substrate, the more thermodynamically efficient the process. The chloride and bromide CCIs were evaluated at the G3(MP2)-RAD(+) level of theory for 120 different R-groups, covering a broad range of carbon-centered and noncarbon-centered species; the effects of solvent and temperature have also been studied. The broad finding from this work is that successful chain carriers generally maximize the strength of their halide (versus hydride bonds) through charge-shift bonding. As a result, the thermodynamic efficiency of a chain carrier tends to increase down the periodic table, and also with the inclusion of stronger electron donating substituents. The CCIs of carbon-centered species fall into a relatively narrow range so that, even when the CCI is maximized through inclusion of lone pair donor OMe or NMe(2) groups, the thermodynamic driving force for dehalogenation of other organic substrates is modest at best, and the process is likely to be kinetically hampered. Among the noncarbon-centered species studied, bismuth- and borane-centered compounds have some of the highest CCI values and, although their kinetics requires further optimization, these classes of compounds would be worth further investigation as tin-free radical reducing agents.

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“…23 The reaction of 4 with Bu3SnH (2.4 equiv, 0.25 M) in refluxing benzene gave the linear product 5 (7% relative yield), the two five-membered cyclized products 6 (84%, trans/cis = 88/12, GC), and 2-phenyltetralin 7 (9%). From GC analysis, 5, 6 and 7 accounted for ca 90% of the total product mixture (Scheme 3).…”

Section: Resultsmentioning

confidence: 99%

Clear-cut difference in the rearrangement of 1-bromo-2-(2-phenyl-3-butenyl)benzene under anionic or radical conditions

Reynaud¹,

Hazimeh²,

Mattalia³

et al. 2011

Arkivoc

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The o-(3-butenyl)phenyl system bearing a phenyl group on the 2-position of the side chain was studied as a potential mechanistic probe for distinguishing between radical and carbanion intermediates. The Bu3SnH reduction of 1-bromo-2-(2-phenyl-3-butenyl)benzene, 4, yields mainly the 1,5-cyclization product, 6, with a preference for the trans-isomer. Treatment of 4 with Mg or t-BuLi leads to double-bond isomerization and yields (E)-1,2-diphenyl-2-butene, 8, along with 3,4-diphenyl-1-butene, 5.

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Tin, Silicon and Related Reducing Agents

Cited by 15 publications

References 89 publications

A case of chain propagation: α-aminoalkyl radicals as initiators for aryl radical chemistry

A case of chain propagation: α-aminoalkyl radicals as initiators for aryl radical chemistry

Effects of Chemical Structure on the Thermodynamic Efficiency of Radical Chain Carriers for Organic Synthesis

Clear-cut difference in the rearrangement of 1-bromo-2-(2-phenyl-3-butenyl)benzene under anionic or radical conditions

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