Mechanistic photochemistry of acylsilanes. 2. Reaction with electron-poor olefins

Dalton, J. Christopher; Bourque, Robert A.

doi:10.1021/ja00393a049

Cited by 69 publications

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“…I3C-NMR (75 MHz): -6.9 (q, 2 CH,-Si); 26.5 (q, 3 CH3-C-Si, CH3-C(2')); 28.3 CH,=C(6')); 54,l (d, C(1')); 16.6 (s, C-Si); 34.8 (s, C(2')); 149.1 (s, C(6')); 246.7 (s, C(1)). MS: 308 (I, M + , C,,H,,OSi), 293 (I), 280 (I), 265 (2), 251 (X), 115 (31), 75 (35), 73 (100) 69 (7), 59 (9), 41 (9). Anal.…”

Section: -mentioning

confidence: 99%

“…9801%' br., 935w, 890m, 870m, 835s. 'H-NMR (300 MHz): 0.06, 0.065, 0.07, 0.1 1 (4s, 2(CH,),Si); 0.83, 0.91 (23, 2 CH,-C(2')); 0.88, 0.92 (2s, 2(CH,),CSi); 1.00-1.85 and 1.95-2.10 (2m, 2H-C(5), 2H-C(6), -7-(2',2'-dimethyl-6'-inefhytidenrcyclohexyl) -2H-C (7), H-C(l'), 2H-C(3'), 2H-C(4'), 2H-C(5')); 4.38, 4.77 (2m, wy2 Y 4, 2H-C(1)); 4.52, 4.72 (2m, ~> y~ Y 4, CH,=C(6')); 5.28 (dd, J I = J~ = 5, H-C(4)). "C-NMR (75 MHz): -6.3, -6.2, -4.0, -3.9, -3.3 (5q, Z(CH,),Si); 25.9, 26.9 (2q, 2(CH3)3CSi, CH3-C(2')); 28.5 (q, CH3-C(2')); 23.4, 23.5, 23.8"), 26.5"), 32.…”

Section: Photolyses Of Thementioning

confidence: 99%

“…Dalton e f ol. have shown that the formation of cyclopropanes on photolysis of acylsilanes in the presence of dimethyl fumarate results from reaction of both the S, and TI states of the acylsilane rather than via addition of a photochemically generated siloxycarbene to the electron poor olefin [7]. solutions on a Varian HA-100 instrument (100 MHz) or, exceptionally (as indicated below), on a Bruker WP-80 CW (80 MHz) or WM 300 (300 MHz) instrument in CDCI,-solutions.…”

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confidence: 99%

“…3- ( 2',prop~~I p-Toluenesu/fonate (7). UV (0.373 mg in 20 ml): 223 (11900); UV (4.06 mg in 5 ml): 256 (140), 261 (430), 267 (400), 272 (350).…”

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confidence: 99%

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Photochemical reactions. 139^th Communication. Photochemistry of acylsilanes: 1. Siloxcarbene formation versus γ‐H‐abstraction

Scheller

Frei

1984

Helvetica Chimica Acta

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Preparation of the Compounds 1 and -The acylsilane 1 and the methyl ketone 2 were synthesized starting from 7,8-dihydro-y-ionone 3 in 17 and 30% overall yields, respectively (see Scheme I ) . Reaction of the iodide 4 (obtained from 3 via 5+6+7 with the 2-lithio derivatives of 8') and 9 [9] [lo] gave the 1,3-dithianes 10 (92%) and 11 (94%) which were dethioacetalized by treatment with Tl(NO,),. 3H,O [ll] [12] affording 1 (54%) and 2 (88%), respectively.given in the Table and the photoproducts depicted in Scheme 2. 3. Photolysis Experiments. -3.1. Irradiation of the Acylsilane 1. The results are Scheme 2 OOH 12 19 13 1 17Prepared by reaction of 2-lithio-1,3-dithiane with (t-buty1)dimethylsilyl chloride

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Section: -mentioning

confidence: 99%

Section: Photolyses Of Thementioning

confidence: 99%

mentioning

confidence: 99%

“…3- ( 2',prop~~I p-Toluenesu/fonate (7). UV (0.373 mg in 20 ml): 223 (11900); UV (4.06 mg in 5 ml): 256 (140), 261 (430), 267 (400), 272 (350).…”

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confidence: 99%

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Photochemical reactions. 139^th Communication. Photochemistry of acylsilanes: 1. Siloxcarbene formation versus γ‐H‐abstraction

Scheller

Frei

1984

Helvetica Chimica Acta

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“…For this reason, we initiated ab initio studies of the thermal rearrangement reactions of α‐silylalcohols 2, silylmethanol, and 1‐silylprop‐2‐en‐1‐ol. The results show that as compared with the rearrangement under strong base 3–9 and peroxide‐initiating 10–18 conditions, two dyotropic 19 rearrangement reactions may occur when α‐silylalcohols are heated. One is via the Brook rearrangement reaction, where the silyl group migrates from carbon atom to oxygen atom coupled with a simultaneous migration of a hydrogen atom from oxygen atom to carbon atom passing through a double three‐membered ring transition state, forming alkyloxysilane.…”

Section: Introductionmentioning

confidence: 96%

Theoretical study of thermal rearrangements of α‐silylalcohols: Effects of substituents attached to the silicon atom on the reactions

Feng

2006

Int J of Quantum Chemistry

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ABSTRACT:To investigate the effects of substituents attached to the silicon atom on the thermal rearrangement reactions of ␣-silyl alcohols, the thermal rearrangement reactions of dimethylsilyl methanol (CH 3 ) 2 SiHCH 2 OH and vinylsilyl methanol CH 2 ACHSiH 2 CH 2 OH were studied by ab initio calculations at the G3 level. Geometries of various stationary points were fully optimized at the MP2(full)/6-31G(d) and MP2(full)/6-311G(d,p) levels, and harmonic vibrational frequencies were calculated at the same levels. The reaction paths were investigated and confirmed by intrinsic reaction coordinate (IRC) calculations at the MP2(full)/6-31G(d) level. The results show that two dyotropic reactions could occur when (CH 3 ) 2 SiHCH 2 OH or CH 2 ACHSiH 2 CH 2 OH is heated. One is Brook rearrangement reaction (reaction A), and the dimethylsilyl or vinylsilyl groups migrates from carbon atom to oxygen atom coupled with a simultaneous migration of a hydrogen atom from oxygen atom to carbon atom passing through a double three-membered ring transition state, forming dimethylmethoxylsilane (CH 3 ) 2 SiHOCH 3 or methoxylvinylsilane CH 2 ACHSiH 2 OCH 3 ; the other is a hydroxyl group migration (reaction B) from carbon atom to silicon atom, coupled with a simultaneous migration of a hydrogen atom from silicon atom to carbon atom, via a double three-membered ring transition state, forming trimethylsilanol (CH 3 ) 3 SiOH or methylvinylsilanol CH 3 SiH(OH)CHACH 2 . The G3 barriers of the reactions A and B were computed to be 312.8 and 241.4 kJ/mol for (CH 3 ) 2 SiHCH 2 OH, and 317.6 and 233.7 kJ/mol for CH 2 ACHSiH 2 CH 2 OH, respectively. On the basis of the MP2(full)/6-31G(d) optimized parameters, vibrational frequencies, and G3 energies, the reaction rate constants k(T) and equilibrium constants K(T) were calculated using canonical variational transition state theory (CVT) with centrifugal-dominant smallcurvature tunneling (SCT) approximation over a temperature range of 400 -1800 K. The influences of methyl and vinyl groups attached to the silicon atom on reactions are discussed.

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The Brook Rearrangement

Yang

et al. 2020

Organic Reactions

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The Brook rearrangement describes the intramolecular silyl group migration from a carbon to an oxygen atom in a “through‐space” fashion. This feature has been extensively applied to develop numerous useful transformations of diverse organosilanes. Some representative examples include formal [3 + 2] and [4 + 3] annulations to construct diverse ring systems, syntheses of configurationally defined silyl enol ethers, multi‐component reactions by Brook rearrangement‐based ARC (anion relay chemistry), and various umpolung processes such as silyl benzoin condensations and sila‐Stetter reactions. This chapter presents a thorough overview of the Brook rearrangement. The scope and limitations are categorized according to the organosilane type. The mechanism and stereochemical course of this process are discussed, as is its application in the synthesis of complex natural products. The literature is covered up to the end of 2019.

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Mechanistic photochemistry of acylsilanes. 2. Reaction with electron-poor olefins

Cited by 69 publications

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Photochemical reactions. 139^th Communication. Photochemistry of acylsilanes: 1. Siloxcarbene formation versus γ‐H‐abstraction

Photochemical reactions. 139^th Communication. Photochemistry of acylsilanes: 1. Siloxcarbene formation versus γ‐H‐abstraction

Theoretical study of thermal rearrangements of α‐silylalcohols: Effects of substituents attached to the silicon atom on the reactions

The Brook Rearrangement

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Mechanistic photochemistry of acylsilanes. 2. Reaction with electron-poor olefins

Cited by 69 publications

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Photochemical reactions. 139th Communication. Photochemistry of acylsilanes: 1. Siloxcarbene formation versus γ‐H‐abstraction

Photochemical reactions. 139th Communication. Photochemistry of acylsilanes: 1. Siloxcarbene formation versus γ‐H‐abstraction

Theoretical study of thermal rearrangements of α‐silylalcohols: Effects of substituents attached to the silicon atom on the reactions

The Brook Rearrangement

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Photochemical reactions. 139^th Communication. Photochemistry of acylsilanes: 1. Siloxcarbene formation versus γ‐H‐abstraction

Photochemical reactions. 139^th Communication. Photochemistry of acylsilanes: 1. Siloxcarbene formation versus γ‐H‐abstraction