Desilylative condensation reactions of electronegatively substituted 1-(trimethylsilyl)cyclopropanes1

Blankenship, Craig; Wells, Gregory J.; Paquette, Leo A.

doi:10.1016/s0040-4020(01)86653-9

Cited by 12 publications

(4 citation statements)

References 60 publications

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“…Next, we aimed at expanding this methodology to another as yet unknown hydrometalation reaction on cyclopropenes: hydrosilylation toward cyclopropylsilanes. While cyclopropylsilanes share some reactivity with cyclopropylstannanes, , they also undergo a number of transformations characteristic of organosilanes, including Tamao−Flemming oxidation 28 and the Peterson olefination reaction, which makes them very attractive synthons in their own right.…”

Section: Resultsmentioning

confidence: 99%

Highly Diastereo- and Regioselective Transition Metal-Catalyzed Additions of Metal Hydrides and Bimetallic Species to Cyclopropenes: Easy Access to Multisubstituted Cyclopropanes

et al. 2007

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The first highly efficient, diastereo- and regioselective transition metal-catalyzed addition of metal hydrides (stannanes, silanes, and germanes) and bimetallic species (ditins and silyltins) to cyclopropenes has been developed. It was shown that the addition across the double bond of cyclopropenes is generally controlled by steric factors and proceeds from the least hindered face. This methodology represents a powerful and atom-economic approach toward a wide variety of highly substituted stereodefined cyclopropylmetals, useful building blocks unavailable by other methods.

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Section: Resultsmentioning

confidence: 99%

Highly Diastereo- and Regioselective Transition Metal-Catalyzed Additions of Metal Hydrides and Bimetallic Species to Cyclopropenes: Easy Access to Multisubstituted Cyclopropanes

et al. 2007

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“…Following this report, Pinnick and co-workers observed the formation of the trimer 43 in addition to the C - and O -silylated products 41 and 42 (R = Et, eq ) . These cyclopropyl ester enolate anions are generally regarded as pyramidalized carbanion centers rather than the O -lithiated planar methylene cyclopropane species …”

Section: Resultsmentioning

confidence: 87%

Enantioselective Total Synthesis of (−)-Acylfulvene and (−)-Irofulven

et al. 2009

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We report our full account of the enantioselective total synthesis of (−)-acylfulvene (1) and (−)-irofulven (2), which features metathesis reactions for the rapid assembly of the molecular framework of these antitumor agents. We discuss (1) the application of an Evans’ Cu-catalyzed aldol addition reaction using a strained cyclopropyl ketenethioacetal, (2) an efficient enyne ring-closing metathesis (EYRCM) cascade reaction in a challenging setting, (3) the reagent IPNBSH for a late stage reductive allylic transposition reaction, and (4) the final RCM/dehydrogenation sequence for the formation of (−)-acylfulvene (1) and (−)-irofulven (2).

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“…Preparation of Tosylhydrazone 23a. A suspension of 167 mg of p-toluenesulfonyl hydrazide (0.897 mmol) in 1 mL of methanol was stirred as a solution of 135 mg of 1-trimethylsilylcyclopropyl methyl ketone 11 (0.866 mmol) in 0.5 mL of methanol was added at room temperature. The mixture became homogeneous, and after 20 h the mixture was cooled in a freezer.…”

Section: Methodsmentioning

confidence: 99%

“…-Trimethylsilylcyclopropylmethyl ketone11 was converted in fashion similar to the tosylhydrazone 23a, and the dry sodium salt was pyrolyzed under vacuum. The(7) For a discussion of the tosylhydrazone salt pyrolysis method of diazocompound and carbene generation, see: (a) Bamford, W. R.; Stevens, T. S. J. Chem.…”

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confidence: 99%

β-Trimethylsilyl Cyclopropylcarbenes

Creary

Butchko

2001

J. Org. Chem.

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Thermal decomposition of the in situ generated lithium salt of the tosylhydrazone derivative of cyclopropyl trimethylsilylmethyl ketone gave 1-cyclopropyl-1-trimethylsilylethylene, a product of exclusive silyl migration. Thermal decomposition of the sodium salts of tosylhydrazone derivatives of 1-trimethylsilylcyclopropyl alkyl ketones also gave methylenecyclopropane products derived from trimethylsilyl migration. These reactions were interpreted in terms of rapid trimethylsilyl migration to carbene-like centers that compete effectively with ring expansion processes of cyclopropylcarbenes. Computational studies (B3LYP/6-31G) suggest that cyclopropyl stabilization of carbenes is more effective than beta-trimethylsilyl stabilization. However, beta-trimethylsilyl stabilized conformations are easily attained, and these conformations can lead to silyl migrations. There are two minimum energy conformations of methyl-1-trimethylsilylcyclopropylcarbene, 27, and the rotational barrier to interconversion of these conformations (5.4 kcal/mol) is substantially lower than in the parent cyclopropylcarbene (15 kcal/mol). The onset of a stabilizing interaction in the transition state between the carbene vacant orbital with the adjacent Si-C sigma-orbital is proposed. Computational studies also show a very small (2.0 kcal/mol) barrier for trimethylsilyl migration in trimethylsilylmethyl cyclopropylcarbene, 11.

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Desilylative condensation reactions of electronegatively substituted 1-(trimethylsilyl)cyclopropanes1

Cited by 12 publications

References 60 publications

Highly Diastereo- and Regioselective Transition Metal-Catalyzed Additions of Metal Hydrides and Bimetallic Species to Cyclopropenes: Easy Access to Multisubstituted Cyclopropanes

Highly Diastereo- and Regioselective Transition Metal-Catalyzed Additions of Metal Hydrides and Bimetallic Species to Cyclopropenes: Easy Access to Multisubstituted Cyclopropanes

Enantioselective Total Synthesis of (−)-Acylfulvene and (−)-Irofulven

β-Trimethylsilyl Cyclopropylcarbenes

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