Optisch aktive O-silyl-β-dicarbonylverbindungen

Kusnezowa, I. K.; Rühlmann, Klaus; Gründemann, E.

doi:10.1016/s0022-328x(00)92839-0

Cited by 35 publications

(3 citation statements)

References 12 publications

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“…again from 'H-NMR. coalescence temperatures, This particular intramolecular reaction has been shown to proceed with retention of configuration at silicon [14].…”

Section: Discussionmentioning

confidence: 98%

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ChemInform Abstract: SYNTHESIS, PROPERTIES, AND CRYSTAL STRUCTURE OF SILYL NITRONATES (SILYL ESTERS OF ACI‐NITROALKANES): TOWARDS THE SN2 REACTION PATH WITH RETENTION OF CONFIGURATION AT SILICON

Colvin¹,

Beck²,

Bastani³

et al. 1980

Chemischer Informationsdienst

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SummaryAn efficient and flexible method for the preparation of silyl nitronates is described (see 1-10). NMR. spectral investigations indicate a rapid 1,3-silyl migration process, with an activation energy of about 10 kcal mol-'. X-ray crystallographic studies on the silyl nitronates 3 and 8 show structures that lean towards an SN2 retention pathway at silicon.Silyl nitronates (the trialkylsilyl esters of nitronic acids (= mi-nitroalkanes)) have been prepared and their chemistry as 1,3-dipolar reagents has been studied by Jofle et al. [l] and Torsell et al. [2]. The method of synthesis employed by Jo#e [ 11 was to heat the appropriate nitroalkane in N , 0-bis (trimethylsily1)acetamide; close to quantitative yields were claimed, but product purification proved to be a problem, with unavoidable contamination by excess silylating agent and acetamide by-products. Although only a limited range of compounds was described, both primary and secondary nitroalkanes could be employed [Equation (l)].

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“…again from 'H-NMR. coalescence temperatures, This particular intramolecular reaction has been shown to proceed with retention of configuration at silicon [14].…”

Section: Discussionmentioning

confidence: 98%

“…It has been studied extensively in the amide derivatives 13 [7], 14 [8], 15 [9], and 16 [lo] [equation (3)]. In the last case, the activation energies for bond-switching were estimated [ 101 from 'H-NMR.…”

Section: Discussionmentioning

confidence: 99%

ChemInform Abstract: SYNTHESIS, PROPERTIES, AND CRYSTAL STRUCTURE OF SILYL NITRONATES (SILYL ESTERS OF ACI‐NITROALKANES): TOWARDS THE SN2 REACTION PATH WITH RETENTION OF CONFIGURATION AT SILICON

Colvin¹,

Beck²,

Bastani³

et al. 1980

Chemischer Informationsdienst

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“…For example, l,l-bis(trimethylsilyl)-l,2-diphenylethane undergoes 32 consecutive 1,2-and 1,4-shifts 33 39 to proceed with retention of stereochemistry at silicon. For example, l,l-bis(trimethylsilyl)-l,2-diphenylethane undergoes 32 consecutive 1,2-and 1,4-shifts 33 39 to proceed with retention of stereochemistry at silicon.…”

Section: ^-Rearrangementsmentioning

confidence: 99%

Rearrangement reactions with migration of silicon

Colvin

1981

Silicon in Organic Synthesis

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Photolysis of Diazo(pentamethyldisilanyl)methyl Ketones in the Presence of Carbonyl Compounds: Trapping of the Acylsilene Intermediates

et al. 1991

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UV photolysis of diazo(pentamethyldisilany1)methyl ketones 1 b -d generates acylsilenes (3-0x0-1-sila-1-propenes) 3 as reactive intermediates, which can be trapped by enolizable carbony1 compounds in an ene-type reaction. With non-enolizable carbonyl compounds or ethyl acetate, they undergo a [4 + 21 cycloaddition. In contrast to the photolysis in the absence of these carbonyl compounds, a Wolff rearrangement of 1 b -d (or the derived carbenes) to silyl ketenes 5b-d is observed as a competitive reaction.Acylsilenes (3-0x0-1-sila-1-propenes) 3 are reactive intermediates, which can be generated from pentamethyldisilanyl-substituted diazocarbonyl compounds 1 on the carbene route. In the absence of trapping reagents, subsequent reactions of 3 take place. Thus, photolysis of 3a -d in benzene yields cyclic isomers (of 3a,b) of [4 + 41 cyclodimers (of 3c,d) as the major products's2). An acylsilene-silylketene rearrangement is the exclusive reaction pathway in both gasphase thermolysis and solution photolysis of ethyl diazo-(pentamethyldisilany1)acetate (1 e)3). In general, silaethenes readily react with various kinds of carbonyl compounds4'. 3-Silaacrylate 3e is no exception since it can be trapped by enolizable (ene reaction ' 3 ' ) ) and non-enolizable ketones ([4 + 21 cycloaddition6), [2 + 21 cycloaddition followed by fragmentation of the 1,2-silaoxetanes thus f~r m e d~.~) ) ; however, the rearrangement to a silylketene remains the dominant reaction pathway. On the other hand, the fast cyclization of adamantyl-substituted acylsilene 3a prevents any intermolecular reaction with carbonyl compounds such as acetone and benzophenone lbJ.In this paper, we show that the behavior of 3a is an exception, since acylsilenes 3b-d can be trapped by both enolizable and non-enolizable carbonyl compounds.

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Optisch aktive O-silyl-β-dicarbonylverbindungen

Cited by 35 publications

References 12 publications

ChemInform Abstract: SYNTHESIS, PROPERTIES, AND CRYSTAL STRUCTURE OF SILYL NITRONATES (SILYL ESTERS OF ACI‐NITROALKANES): TOWARDS THE SN2 REACTION PATH WITH RETENTION OF CONFIGURATION AT SILICON

ChemInform Abstract: SYNTHESIS, PROPERTIES, AND CRYSTAL STRUCTURE OF SILYL NITRONATES (SILYL ESTERS OF ACI‐NITROALKANES): TOWARDS THE SN2 REACTION PATH WITH RETENTION OF CONFIGURATION AT SILICON

Rearrangement reactions with migration of silicon

Photolysis of Diazo(pentamethyldisilanyl)methyl Ketones in the Presence of Carbonyl Compounds: Trapping of the Acylsilene Intermediates

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