1,3-γ-Silyl-elimination in electron-deficient cationic systems

Mercadante, Michael; Kelly, Christopher B.; Hamlin, Trevor A.; Chiaie, Kayla R. Delle; Drago, Michael D.; Duffy, Katherine K.; Dumas, Megan T.; Fager, Diana C.; Glod, Bryanna L. C.; Hansen, Katherine E.; Hill, Cameron R.; Leising, Rebecca M.; Lynes, Catherine L.; MacInnis, Allyson E.; McGohey, Madeline R.; Murray, Stephanie A.; Piquette, Marc C.; Roy, Shaina L.; Smith, Ryan M.; Sullivan, Katherine R.; Truong, Bao; Vailonis, Kristina M.; Gorbatyuk, Vitaliy; Leadbeater, Nicholas E.; Tilley, Leon J.

doi:10.1039/c4sc01732c

Cited by 20 publications

(15 citation statements)

References 85 publications

(12 reference statements)

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“…Attention was next turned to cyclopropylcarbinyl systems substituted with electron-withdrawing groups. Previously Tilley and co-workers [55] have examined the triflate 53 and found that this system solvolyzes with rear lobe TMS participation (Scheme 11). The unusual feature in solvolysis of 53 is the formation of the highly strained bicyclobutane 55 as the sole product.…”

Section: Resultsmentioning

confidence: 99%

“…They are greatly stabilized by the “rear lobe” type of interaction shown involving the γ-trimethylsilyl group. A number of related cations are also stabilized by analogous γ-silyl interactions [55–59], which have also been termed ”percaudal” interactions [56]. Certain carbenes can also be stabilized in a similar fashion [60–61].…”

Section: Introductionmentioning

confidence: 99%

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The cyclopropylcarbinyl route to γ-silyl carbocations

Creary¹

2019

Beilstein J. Org. Chem.

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The mesylate derivative of cis-1-hydroxymethyl-2-trimethylsilylcyclopropane has been prepared, along with a number of related mesylates and triflates with substituents on the 1-position. These substrates all solvolyze in CD3CO2D to give products derived from cyclopropylcarbinyl cations that undergo further rearrangement to give 3-trimethylsilylcyclobutyl cations. These 3-trimethylsilylcyclobutyl cations are stabilized by a long-range rear lobe interaction with the γ-trimethylsilyl group. When the substituent is electron-withdrawing (CF3, CN, or CO2CH3), significant amounts of bicyclobutane products are formed. The bicyclobutanes are a result of γ-trimethylsilyl elimination from the cationic intermediate that has an unusually long calculated Si–C bond. The solvolysis chemistry of mesylate and triflate derivatives of trans-1-hydroxymethyl-2-trimethylsilylcyclopropane and 1-substituted analogs can be quite different since these substrates do not generally lead to 3-trimethylsilylcyclobutyl cations.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The cyclopropylcarbinyl route to γ-silyl carbocations

Creary¹

2019

Beilstein J. Org. Chem.

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“…We hypothesized that if we were to use solvolysis conditions in which we proceed through a formal, albeit destabilized, α‐CF 3 carbocation, we could circumvent these steric restrictions. Moreover, the NGP of an electron‐rich π bond is far less transient than the homohyperconjugative stabilization of our previously studied γ‐silyl example,4b so CRC should be the predominant outcome.…”

Section: Scope Of the Cationic Cyclization Reaction[a][b][c][d][e][fmentioning

confidence: 66%

“…Despite being a gateway to many other CF 3 cyclopropane derivatives, TVCPs are essentially unknown in the literature. In fact, the only reported example was in our previous study 4b. The scarcity of compounds of this class can be attributed to their challenging preparation using current cyclopropanation methods.…”

Section: Scope Of the Cationic Cyclization Reaction[a][b][c][d][e][fmentioning

confidence: 96%

“…Recently, we discovered that this enhancement of NGP can be utilized to effect cationic ring closure (CRC) in γ‐silyl‐substituted systems via 1,3 γ‐silyl elimination 4,5. We exploited this phenomenon in a targeted synthesis4a of perfluoroalkyl‐substituted bicyclobutanes [Figure 1, Equation (4)] and advanced it into a methodology4b for the preparation of trifluoromethyl‐functionalized cyclopropanes [Equation (5)]. These fluorinated small‐ring motifs combine two highly desirable substructures frequently employed in medicinal chemistry programs: the cyclopropyl and trifluoromethyl groups 1,6.…”

Section: Scope Of the Cationic Cyclization Reaction[a][b][c][d][e][fmentioning

confidence: 99%

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Synthesis of Perfluoroalkyl‐Substituted Vinylcyclopropanes by Way of Enhanced Neighboring Group Participation

et al. 2015

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A simple, high yielding, two‐step, one‐pot protocol for the preparation of trifluoromethyl‐substituted vinylcyclopropanes from α‐CF3 homoallyl alcohols is disclosed. Destabilization of the cationic intermediate by the electron‐withdrawing CF3 group greatly enhances neighboring group participation of the alkene, allowing ring closure to predominate. The reaction can be extended to the difluoromethyl and pentafluoroethyl group, enabling the preparation of a diverse array of fluoroalkyl‐substituted vinylcyclopropanes.

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Taming of Furfurylidenes by Chiral Bismuth‐Rhodium Paddlewheel Catalysts. Preparation and Functionalization of Optically Active 1,1‐Disubstituted (Trifluoromethyl)cyclopropanes

Peeters,

Decaens,

Fürstner

2023

Angewandte Chemie

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Although 2‐furyl‐carbenes (furfurylidenes) are prone to instantaneous electrocyclic ring opening, chiral [BiRh]‐paddlewheel complexes empowered by London dispersion allow (trifluoromethyl)furfurylidene metal complexes to be generated from a bench‐stable triftosylhydrazone precursor. These reactive intermediates engage in asymmetric [2+1] cycloadditions and hence open entry into valuable trifluoromethylated cyclopropane or ‐cyclopropene derivatives in optically active form, which are important building blocks for medicinal chemistry but difficult to make otherwise.

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1,3-γ-Silyl-elimination in electron-deficient cationic systems

Cited by 20 publications

References 85 publications

The cyclopropylcarbinyl route to γ-silyl carbocations

The cyclopropylcarbinyl route to γ-silyl carbocations

Synthesis of Perfluoroalkyl‐Substituted Vinylcyclopropanes by Way of Enhanced Neighboring Group Participation

Taming of Furfurylidenes by Chiral Bismuth‐Rhodium Paddlewheel Catalysts. Preparation and Functionalization of Optically Active 1,1‐Disubstituted (Trifluoromethyl)cyclopropanes

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