Silene equivalents through the rhodium-catalysed reactions of α-hypersilyl diazoesters: a computational and experimental study

Czyzewski, Michal; Bower, Justin; Box, Matthew; Ottosson, Henrik; Steel, Patrick G.

doi:10.1039/c1sc00405k

Cited by 9 publications

(3 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…26 In studies designed to improve access to silenes, the rhodium heptafluorobutyrate-catalyzed decomposition of a silylated diazo ester (so-called α-hypersilyl) gives rearrangement to a short-lived cyclic sila-oxetene identified by NMR, which is converted to an isolated ketene, which can also be captured by alcohols (eq 29). 27 Computational studies indicate the reaction occurs by initial carbene formation, followed by formation of the cyclic silene and then conversion to the ketene by ethoxy group migration. Aryl diazo ketone conversion into the silylated diazo ketone 25 in a one-pot procedure using a silyl triflate and then Wolff rearrangement catalyzed by triflic acid generates the stable aryl(trialkylsilyl)ketene 26 (eq 30).…”

Section: Introductionmentioning

confidence: 99%

Ketenes and Other Cumulenes as Reactive Intermediates

2013

View full text Add to dashboard Cite

Section: Introductionmentioning

confidence: 99%

Ketenes and Other Cumulenes as Reactive Intermediates

2013

View full text Add to dashboard Cite

“…From the conceptual viewpoint, this new approach to structurally diverse cyclopropyl building blocks of type 3 is orthogonal to the established cyclopropanation chemistry in that it does not mandate a library of different diazo derivatives 4 that need to be prepared individually; rather, a single α-metalated carbene precursor that allows for appropriate functionalization after the event will suffice. Because compounds 1 and analogues are easy to make on scale, − safe to handle, and storable for months, this late-stage diversity aspect is a potential asset. − …”

Section: Introductionmentioning

confidence: 99%

From Serendipity to Rational Design: Heteroleptic Dirhodium Amidate Complexes for Diastereodivergent Asymmetric Cyclopropanation

et al. 2022

View full text Add to dashboard Cite

A heteroleptic dirhodium paddlewheel complex comprising three chiral carboxylate ligands and one achiral acetamidate ligand has recently been found to be uniquely effective in catalyzing the asymmetric cyclopropanation of olefins with α-stannylated (silylated and germylated) α-diazoacetate derivatives. A number of control experiments in combination with detailed computational studies provide compelling evidence that an interligand hydrogen bond between the −NH group of the amidate and the ester carbonyl group of the reactive rhodium carbene intermediate plays a quintessential role in the stereodetermining transition state. The penalty for distorting this array outweighs steric arguments and renders two of the four conceivable transitions states unviable. Based on this mechanistic insight, the design of the parent catalyst is revisited herein: placement of appropriate peripheral substituents allows high levels of diastereocontrol to be imposed upon cyclopropanation, which the original catalyst lacks. Because the new complexes allow either trans- or cis-configured stannylated cyclopropanes to be made selectively and in excellent optical purity, this transformation also marks a rare case of diastereodivergent asymmetric catalysis. The products are amenable to stereospecific cross coupling with aryl halides or alkenyl triflates; these transformations appear to be the first examples of the formation of stereogenic quaternary carbon centers by the Stille reaction; carbonylative coupling is also achieved. Moreover, tin/lithium exchange affords chiral lithium enolates, which can be intercepted with a variety of electrophilic partners. The virtues and inherent flexibility of this new methodology are illustrated by an efficient synthesis of two salinilactones, extremely scarce bacterial metabolites with signaling function involved in the self-regulatory growth inhibition of the producing strain.

show abstract

“…Use of transition-metal catalysis for the generation of silene species or their equivalents has also attracted much interest, because these catalysts may promote not only silene generation but also subsequent reactions through the formation of transition-metal–silene complexes. Several transition-metal-catalyzed reactions involving the generation of silene have been reported to date. − They can be classified into four categories on the basis of the reaction mechanism (Scheme ): (a) oxidative addition of the Si–H bond of alkylsilane followed by β-H elimination to afford η 2 -silene complex A , (b) oxidative addition of the Si–Si bond of alkynyldisilane and subsequent 1,3-rearrangement to 3-sila-1,2-propadienyl complex B , (c) oxidative addition of the Si–Si bond of 3,4-benzo-1,2-disilacyclobutene to give o -quinodisilane C , and (d) formation of a silyl-substituted carbene complex from an α-diazocarbonyl compound followed by 1,2-rearrangement of one of the substituents on the silicon atom to afford D . Reaction types a–c, which rely on Si–E (E = H, Si) bond activation, require high reaction temperatures (generally 150–220 °C).…”

Section: Introductionmentioning

confidence: 99%

Palladium-Catalyzed β-Elimination of Aminoboranes from (Aminomethylsilyl)boranes Leading to the Formation of Silene Dimers

2017

View full text Add to dashboard Cite

Silylboronic esters bearing a N,N-dialkylaminomethyl group on the silicon atoms were synthesized and used in palladium-catalyzed reactions. Five silylboronic esters were synthesized through a reaction of the [(N,N-dialkylaminomethyl)diorganosilyl]lithiums with i-PrOB(pin). An addition reaction of the silylboronic ester to ethynylbenzene (silaboration) took place efficiently by a phosphine- and isocyanide-free palladium catalyst to give (E)-1-silyl-2-boryl-1-phenylethene in a regio- and stereoselective manner. On the other hand, the silylboronic esters underwent β-elimination reactions in the presence of a palladium catalyst and styrene to afford 1,3-disilacyclobutanes and aminoboranes in good yields. This may be due to the generation of silene intermediates during the reaction. It should be noted that use of styrene as a ligand was essential for the generation of the silene species.

show abstract

Silene equivalents through the rhodium-catalysed reactions of α-hypersilyl diazoesters: a computational and experimental study

Cited by 9 publications

References 51 publications

Ketenes and Other Cumulenes as Reactive Intermediates

Ketenes and Other Cumulenes as Reactive Intermediates

From Serendipity to Rational Design: Heteroleptic Dirhodium Amidate Complexes for Diastereodivergent Asymmetric Cyclopropanation

Palladium-Catalyzed β-Elimination of Aminoboranes from (Aminomethylsilyl)boranes Leading to the Formation of Silene Dimers

Contact Info

Product

Resources

About