Silicon-carbon unsaturated compounds.

Ohshita, Joji; Masaoka, Yoshiteru; Masaoka, Shin; Ishikawa, Mitsuo; Tachibana, Akitomo; Yano, Toshiro; Yamabe, Tokio

doi:10.1016/0022-328x(94)80100-2

Cited by 37 publications

(7 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the basis of the chemical shifts of the central silicon atoms of the lithium silenolates which appear in the same region as those for similarly substituted silyl silenol ethers, (Me 3 Si) 2 SiC(OSiMe 3 )R, reported by Brook et al., they concluded that the central Si−C bonds of the lithium silenolates have high double-bonding character and that the lithium silenolates can be understood as silenoxylithiums rather than (acylsilyl)lithiums. However, when we followed the same reaction, we could not observe 29 Si NMR signals reported by these authors …”

Section: Introductionmentioning

confidence: 54%

“…As reported in ref , we have carried out geometry optimization of the products containing a lithium cation by the semi-empirical calculation method and found that the final product obtained from reaction B is a lithium-bridged complex, (H 3 Si) 3 SiLiOC(CH 3 ) 2 , but not a pair of separated molecules, 19 and (H 3 Si) 3 SiLi. We have attempted to obtain optimized geometries of the products in the presence of the lithium cation, by using ab initio calculations, but have not yet succeeded.…”

Section: Referencesmentioning

confidence: 73%

“…Theoretical Studies. In order to learn more about the formation of lithium silenolates from the reactions of acylpolysilanes with silyllithium reagents, we carried out molecular orbital calculations using GAUSSIAN 92 on a model reaction of (H 3 Si) 3 SiCOCH 3 ( 1j ) with the H 3 Si anion ( 2c ) . The geometries of all compounds were optimized at the HF/6-31G* level.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Silicon−Carbon Unsaturated Compounds. 55. Synthesis and Reactions of Lithium Silenolates, Silicon Analogs of Lithium Enolates

Ohshita¹,

Masaoka²,

Masaoka³

et al. 1996

Organometallics

Self Cite

View full text Add to dashboard Cite

Chemical behavior of acylpolysilanes, (Me3Si)3SiCOR (1a, R = Mes; 1b, R = o-Tol; 1c, R = Ad; 1d, R = t-Bu; 1g, R = Ph; 1h, R = Me), toward silyllithium reagents has been studied. Reactions of 1a−d with [tris(trimethylsilyl)silyl]lithium gave the corresponding lithium silenolates, (Me3Si)2SiCROLi (5a, R = Mes; 5b, R = o-Tol; 5c, R = Ad; 5d, R = t-Bu), in high yield by removal of a trimethylsilyl group from the acylpolysilane. However, a similar reaction of 1g gave an unstable lithium silenolate, which undergoes dimerization and then further reactions under the conditions used. Acetylpolysilane 1h did not afford the lithium silenolate but gave lithium [tris(trimethylsilyl)silyl]ethenolate. Lithium silenolate 5a was produced also by treating 1a with (dimethylphenylsilyl)lithium. The reactions of 1b,c with (dimethylphenylsilyl)lithium proceed in a different fashion from that of 1a to afford products arising from addition of the silyllithium to the carbonyl bond as major products. Lithium silenolates 5a,c,d are stable at low temperature in THF solution and can be characterized by NMR spectroscopy. Silenolates 5a−d reacted with alkyl halides to afford Si-alkylated products in high yield. Treatment of 5a,b with chlorotriethylsilane led to the formation of silenes arising from O-silylation of the lithium silenolates, almost quantitatively, while 5c,d gave the corresponding acylpolysilanes by Si-silylation in high yield. Results of theoretical studies which were carried out using the reaction of (H3Si)3SiCOCH3 with H3SiLi as a model also are described.

show abstract

Section: Introductionmentioning

confidence: 54%

Section: Referencesmentioning

confidence: 73%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Silicon−Carbon Unsaturated Compounds. 55. Synthesis and Reactions of Lithium Silenolates, Silicon Analogs of Lithium Enolates

Ohshita¹,

Masaoka²,

Masaoka³

et al. 1996

Organometallics

Self Cite

View full text Add to dashboard Cite

show abstract

“…The chemistry of lithium enolates has been extensively investigated and widely used for the synthesis of various organic compounds . On the other hand, no reports on the chemistry of lithium silenolates, silicon analogs of lithium enolates, had been published until recently, when we reported the first example for the synthesis of lithium silenolates . We have demonstrated that treatment of acyltris(trimethylsilyl)silane with (tris(trimethylsilyl)silyl)lithium affords lithium silenolates in almost quantitative yields, if the starting acyltris(trimethylsilyl)silanes have no enolizable protons and involve a bulky substituent, such as a tert -butyl, adamantyl, and mesityl group, at the carbonyl carbon atom .…”

Section: Introductionmentioning

confidence: 90%

Silicon−Carbon Unsaturated Compounds. 60. Reactions of Lithium Silenolates with Dienes

et al. 1997

Self Cite

View full text Add to dashboard Cite

The chemical properties of lithium silenolates toward dienes were studied. The reaction of lithium 2-tert-butyl-1,1-bis(trimethylsilyl)silen-2-olate (1a) with butadiene at −40 °C, followed by hydrolysis, afforded 2-tert-butyl-1,1-bis(trimethylsilyl)silacyclohex-4-en-2-ol, derived from [2 + 4] cycloaddition of 1a with butadiene, in 94% yield. Similar treatment of lithium 2-adamantyl-1,1-bis(trimethylsilyl)silen-2-olate (1b) gave the respective adduct in 87% yield. The reactions of lithium silenolates 1a,b with 2,3-dimethylbutadiene, isoprene, and 1,3-pentadiene proceeded in a fashion similar to those with butadiene to give the [2 + 4] cycloadducts in high yields. The reactions of 1a,b with 2,3-dimethylbutadiene and butadiene at room temperature gave the products originated from 1,1-bis(trimethylsilyl)silacyclohexa-1,4-diene intermediates. The crystal structure of 10-adamantyl-2,3,6,7-tetramethyl-9-(trimethylsilyl)-9-silabicyclo[4.4.0]deca-2,6-diene (6b), which was obtained from the reaction of 1b with 2,3-dimethylbutadiene at room temperature, was determined by a single-crystal X-ray diffraction study.

show abstract

“…In the course of our studies concerning the chemical behavior of acylpolysilanes toward organolithium reagents, we have demonstrated that the reactions of acyltris(trimethylsilyl)silanes with silyllithium reagents cleanly proceed to give the corresponding lithium silenolates by elimination of a trimethylsilyl group, if the acylpolysilanes have no enolizable protons and involve a sterically bulky group on the carbonyl carbon . Lithium silenolates are silicon analogs of lithium enolates and react readily with several electrophiles, such as alkyl halides and triethylchlorosilane, to give the coupling products.…”

mentioning

confidence: 99%

Oxidative Coupling of Lithium Silenolates: First Synthesis of Bis(acyl)-Substituted Polysilanes

1996

Self Cite

View full text Add to dashboard Cite

show abstract

Silicon-carbon unsaturated compounds.

Cited by 37 publications

References 7 publications

Silicon−Carbon Unsaturated Compounds. 55. Synthesis and Reactions of Lithium Silenolates, Silicon Analogs of Lithium Enolates

Silicon−Carbon Unsaturated Compounds. 55. Synthesis and Reactions of Lithium Silenolates, Silicon Analogs of Lithium Enolates

Silicon−Carbon Unsaturated Compounds. 60. Reactions of Lithium Silenolates with Dienes

Oxidative Coupling of Lithium Silenolates: First Synthesis of Bis(acyl)-Substituted Polysilanes

Contact Info

Product

Resources

About