Stabilizing a singlet methylene

Gleiter, Rolf; Hoffmann, Roald

doi:10.1021/ja01022a023

Cited by 260 publications

(143 citation statements)

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“…[17][18][19] The structural characters, thermochemistry, and isomerization of C 3 H 2 carbenes have been investigated extensively. 13,18,[20][21][22] It was found that the singlet cyclopropenylidene is the most stable isomer among the three species, [23][24][25][26] which is lower in energy by about 42-59 and 59-92 kJ/mol than that of propadienylidene and propynylidene, respectively.…”

Section: 12mentioning

confidence: 99%

Theoretical Study on the Mechanism of the Addition Reaction between Cyclopropenylidene and Formaldehyde

Tan¹,

Li²,

Sun³

et al. 2012

Bulletin of the Korean Chemical Society

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Section: 12mentioning

confidence: 99%

Theoretical Study on the Mechanism of the Addition Reaction between Cyclopropenylidene and Formaldehyde

Tan¹,

Li²,

Sun³

et al. 2012

Bulletin of the Korean Chemical Society

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“…The fact that di~~~ctl~oxyalkylsilanes rearrange much more readily than the monoalkoxysilane may bc explained, at least in part, by the anticipated cxtra stability of metl~oxyphenylcarbene relative to phenylcarbcne because of the possibility of sharing lone pair electrons on oxygen with the carbenoid carbon (18). was prepared in a n a n a l o g o~~s manner to the above.…”

Section: Meo-c-phmentioning

confidence: 99%

Alkoxycarbenes from the thermolysis of silyl ketals

Brook¹,

Dillon²

1969

Can. J. Chem.

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It is shown that a,a-dimethoxybenzylsilancs thermally rearrange to give methoxysilanes and phenylmcthoxycarbene; the latter species has been trappcd by a variety of reagents. The rcarrangcment involves rctcntion of config~~ration at an asymmetric silicon center. Whilc a,a-dimctlioxycthylsilancs eliminate methanol when heated, metlioxybenzhydrylsilancs rcarrangc to methoxysilane and diphcnylcarbene b~~i ~~~onorncthoxybenzylsilanes or 2-silyldioxolancs do not thermally rearrange up to 250".Czinadian Journal of Chemistry, 47, 4347 (1969) The thermolysis of niethoxypolysilanes has been reported to produce divalent organosilico~i (silylene) species (1,2). It seemed possible that a-alkoxyalkylmonosilanes might similarly ~lnder-go this sort of reaction to produce carbenes, and indeed, since this work was completed, Atwell et al. have reported such behavior on therrnolysis of (di1netlioxyniethy1)trimethoxysilaiie (3). a-Alkoxyalkylsilanes are generally difficult to synthesize, but a convenient source was found to be the ketals 1 of acylsilancs, which could be prepared either rrom tlie dithiane precursors (4,5) of the acylsilancs by reaction in methanol over several days with a ~n i x t~~r e of mercuric prepared from the acylsilanes and ethylene glycol i n hot clilor~form containing boron trifluoride ethcratc. Attempts to prepare simple ketals using boron trifluoride etlierate and alcohols were not successful. Details of tlie c o n i p o~~n d s prepared will be found in the Experimental section.While tlie dioxolanes of acetyl and benzoyltriphenylsilane were thermally stable to at least 250°, it was found that the dimethoxy ketals, when pyrolyzed at 150-20O0, readily decoliiposed in one of two ways. Where there was hydrogen a to the carbon bearing the alkoxy groups, e.g. l b , methanol was thermally eliminated and an en01 ether was formed. This type of reaction has been For personal use only.

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“…The halocarbenes and carbenes are important transient intermediates in organic synthesis [2], in organometallic chemistry [3] and in gas phase combustion [4,5]. In the ground state the singlet halocarbenes are stabilized over the triplet carbenes by a large σ -p π separation [6,7,8] and inductive/ mesomeric effects or a combination of both the effects. The vacant p π and the occupied σ orbitals make them electrophiles and nucleophiles respectively.…”

Section: Introductionmentioning

confidence: 99%

C-H Functionalisation Through Singlet Chlorocarbenes Insertions – MP2 and DFT Investigations

Ramalingam

Ramasami²,

Venuvanalingam

et al. 2006

Computational Science – ICCS 2006

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Abstract. The insertion reactions of singlet mono and dichlorocarbenes ( 1 CHCl and 1 CCl 2 ) into primary, secondary and tertiary C-H bonds of methane, ethane, propane, n-butane and iso-butane have been investigated at ab initio (MP2) and DFT levels invoking 6-31g(d, p) basis set. Among the σ and π insertions into the said alkane C-H, both MP2 and DFT predict that the σ approach is slightly favoured over the π approach. For inverted σ approach the barrier heights have been found to be ca. 2 to 5 times that of the normal σ approach.

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Stabilizing a singlet methylene

Cited by 260 publications

References 0 publications

Theoretical Study on the Mechanism of the Addition Reaction between Cyclopropenylidene and Formaldehyde

Theoretical Study on the Mechanism of the Addition Reaction between Cyclopropenylidene and Formaldehyde

Alkoxycarbenes from the thermolysis of silyl ketals

C-H Functionalisation Through Singlet Chlorocarbenes Insertions – MP2 and DFT Investigations

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