Silylcupration Of Allene Research Articles

One‐Pot Synthesis of 2,7‐Dioxabicyclo[2.2.1]heptanes from Oxoallylsilanes

AbstractA one‐pot high‐yielding synthesis of silylated 2,7‐dioxabicyclo[2.2.1]heptanes from oxoallylsilanes is described. The mechanism of this tandem reaction is a sequential epoxidation of the allylsilane moiety and subsequent intramolecular cyclization. This simple protocol allows the synthesis of epoxy‐bridged tetrahydropyrans from allene in two high‐yielding steps: silylcupration of allene (followed by capture of the intermediate cuprate with enones) and treatment of the oxoallylsilanes thus obtained with MCPBA. However, under the same conditions, oxovinylsilanes yielded epoxysilyl ketones in a very stereoselective manner.

Seven-Membered Ring Formation from Cyclopropanated Oxo- and Epoxyallylsilanes

A useful strategy for cycloheptane annulations from oxo- and epoxyallylsilanes, prepared by silylcupration of allenes, has been developed, and their application to the stereoselective synthesis of 4-methylenecycloheptan-1-ols is of great potential in the construction of seven-membered ring natural products presented.

One-pot multicoupling reaction of silylcopper reagents, organolithium compounds and α,β-unsaturated nitriles

The silylcupration of allene using a lower order silylcopper species gives an allylsilane-vinyl copper intermediate 2 which, in conjunction with an organolithium reagent, is able to participate in a one-pot multicoupling reaction with α,β-unsaturated nitriles. The scope of this tandem reaction is studied and a possible mechanism pathway is outlined.

ChemInform Abstract: Silylcupration of Allenes and Subsequent Electrophilic Trapping by Allylic Phosphates. A Novel Approach to Silylated 1,4-Diene Systems.

ChemInform Abstract: Silylcupration of Allenes and Subsequent Electrophilic Trapping by Allylic Phosphates. A Novel Approach to Silylated 1,4-Diene Systems.

New synthetic approach to 3-methylene-1-cyclohexanols fused to five, six and seven-membered carbocycles through intramolecular cyclization of epoxyallylsilanes

Silylcupration of allene followed by conjugate addition to enones and carbonyl epoxidation provides a simple and high yielding route to epoxyallylsilanes carrying the useful phenyldimethylsilyl group. Lewis acid catalyzed intramolecular cyclization of epoxyallylsilanes is a powerful strategy for carbocyclic annulation of much potential in synthesis. In this article we show A general procedure for the synthesis of 3-methylene-1-cyclohexanols fused to five, six and seven-membered carbocycles by intramolecular cyclization of epoxyallylsilanes, which might be of great interest as an approach to bicyclic systems contained in many naturally occurring products, is described.

Intramolecular carbonyl-ene reactions in allylsilanes

Silylcupration of allenes has become one of the most efficient procedures for the synthesis of allylsilanes. These substrates are useful building blocks in organic synthesis since they undergo a great variety of highly stereocontrolled silicon-assisted transformations. In particular, the intramolecular carbonyl-ene reaction of oxo-allylsilanes is a powerful strategy for carbocyclic annulation of much potential in synthesis. This article shows a general survey of the recent advances in this field together with the late contributions of our lab to this subject.

Spiro‐Cyclopropanation from Oxoallylsilanes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Silylcuprates from Allene and Their Reaction with α,β-Unsaturatedd Nitriles and Imines. Synthesis of Silylated Oxo Compounds Leading to Cyclopentane and Cycloheptane Ring Formation

The silylcupration of allenes and the subsequent capture of the intermediate cuprate with alpha,beta-unsaturated nitriles is reported. The influence of the substitution of the nitrile, the nature of the silylcopper species, and the temperature on the selectivity of the reaction is studied. An interesting diaddition process was observed (1,2-addition and 1,4-addition), leading to oxo compounds which simultaneously have an allylsilane and a vinylsilane group. The different reactivity of these two units has been employed in the intramolecular allylsilane-terminated cyclization of these adducts, where the vinylsilane moiety remains unchanged. To shed some light on the reaction pathway, the behavior of alpha,beta-unsaturatedd imines was also checked and a new and convenient way for cycloheptane annulation presented. In light of the former results a feasible mechanism is proposed.

Spiro-Cyclopropanation from Oxoallylsilanes

A novel highly stereoselective spiro-cyclopropanation reaction from oxoallylsilanes is described. Oxoallylsilanes are readily obtained by silylcupration of allene followed by conjugate addition to enones. The former oxoallylsilanes undergo a tandem cyclization-cyclopropanation reaction when treated with CH2I2/Me3Al, leading to hydroxylated polycyclic systems bearing the spiro-cyclopropane moiety. The scope of the process is studied, and a feasible pathway is discussed.

A tandem allylsilane–vinylsilane difunctionalization by silylcupration of allene followed by reaction with α,β-unsaturated nitriles

Silylcupration of allene using phenyldimethylsilylcopper 1 followed by BF3-mediated reaction with alpha,beta-unsaturated nitriles at -40 degrees C affords allylsilane-vinylsilane-containing ketones resulting from consecutive addition (1,2 and 1,4) of the intermediate allyl- and vinylcopper species formed in the silylcupration of allene.

Functionalised Allylsilanes from Silylcopper Reagents and Allene. A Useful Strategy for Cyclopentane Annulations

Silylcupration of allene using phenyldimethylsilylcopper or t-butyldiphenylsilylcopper followed by reaction with α,β-unsaturated acyl chlorides, aldehydes or ketones affords allylsilane-containing divinyl ketones and oxoallylsilanes, respectively. They undergo highly stereocontrolled silicon-assisted intramolecular cyclizations when treated with protic or Lewis acid leading to cyclopentane ring-formation.

Silylcupration of allenes and subsequent electrophilic trapping by allylic phosphates. A novel approach to silylated 1,4-diene systems

[formula: see text] Silylcupration of allenes with a lower order silylcuprate reagent followed by an electrophilic trapping reaction with allylic diphenyl phosphates has been studied. This reaction provides a new route to 1,4-diene systems having an allylsilane moiety.

ChemInform Abstract: Silylcupration of Allenes Followed by Reaction with Enones. A New Strategy for the Synthesis of Methylenecyclopentanols.

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Silylcupration of allenes followed by reaction with enones. A new strategy for the synthesis of methylenecyclopentanols

Silylcupration of allene using phenyldimethylsilyl-copper followed by conjugated addition to α,β-unsaturated ketones affords oxoallylsilanes with different substitution patterns. When the former oxoallylsilanes are treated with a Lewis acid they undergo highly stereoselective allylsilane terminated cyclization leading to mono-, bi-, and tricyclic methylenecyclopentanols.

The stereochemistry of the silyl-cupration of allenes

The silyl-cupration of the stereochemically defined allenes 6 and 7 is stereospecifically syn, giving the allylsilanes 8 and 9, respectively

ChemInform Abstract: Silyl‐Cupration of Allene. A New Route to Silylated Synthons.

AbstractStarting with allene (I), the 2‐iodo‐3‐silylpropene (IV) is prepared via the cuprate (III).

Silyl-cupration of allene. A new route to silylated synthons

Silyl-cupration of allene followed by treatment with iodine anomalously gives the vinyl iodine 4 , a versatile synthetic intermediate.

The syntheses of allylsilanes and vinylsilanes by silyl-cupration of allenes

Allenes react with silyl-cuprate reagents to give either allysilanes or vinylsilanes, depending upon the substituents on the allene.