Palladium-catalyzed regiocontrolled alpha-arylation of trimethylsilyl enol ethers with aryl halides

Inter- and intramolecular arylations of trimethylsilyl enol ethers with aryl halides are accomplished regiospecifically in the presence of a palladium catalyst and tributyltin fluoride in refluxing benzene or toluene. The optimal catalyst system called for the use of Pd2(dba)3 and tri-tert-butylphosphine in ca. 1:2 ratio. Aryl iodides, bromides, and chlorides are all effective arylation partners in this reaction. [reaction: see text]     

Organometallic compounds in organic synthesis: reactions of some tricarbonylcyclohexadienylium-iron complexes with trimethylislyl enol ethers

O-Silylated enolates derived from ketones react with tricarbonylcyclohexadienyl-iron cationic complexes under very mild conditions to form carbon-carbon bonds in excellent yields.     

Reaction of silyl enol ethers with cyanogen chloride

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1447–1448, June, 1988.     

Evaluation of C-trialkylsilyl enol and thioenol ethers as intermediates in the synthesis of acylsilanes

C-silyl enol ethers or thioenol ethers have been prepared by a Peterson reaction, as intermediates for acylsilane synthesis. Bis(trialkylsilyl)(methoxy)- or -(methylsulfanyl)methanes bearing identical or different trialkylsilyl groups were used as starting materials in order to assess the selectivity of the Peterson elimination step. A good selectivity was observed only with ethers bearing the TMS and TBDMS groups. However, there is no practical interest to use such reagents owing to the difficulty to obtain them in correct yields. Bis(trimethylsilyl)(methylsulfanyl)methane proved to be a good reagent for the preparation of C-silyl thioenol ethers, which are hydrolyzed under classical acid conditions to give acylsilanes in fair overall yields. This convenient procedure was extended to the synthesis of bis(acylsilanes).     

Reaction of chloromethylcarbene with trimethylsilyl enol ethers. Synthesis of eucarvone, (±)-nuciferal and (±)-manicone.

New synthesis of Eucarvone $\text{7}$, (±)-Nuciferal $\text{12}$ and (±)-Manicone $\text{16}$ are described from trimethylsilyl enol ethers $\text{2}$, $\text{10}$ and $\text{14}$ via their chloromethylenation products by means of a two carbons homologation reaction.     

Condensation of enol silyl ethers and dialkoxymethanes catalyzed by trimethylsilyl trifluoromethanesulfonate. Regiospecific synthesis of α-alkoxymethyl ketones

A facile, regiospecific entry to α-alkoxymethyl ketones is described.     

A novel aminomethylation of silyl enol ethers with aminomethyl ethers catalyzed by iodotrimethylsilane or trimethylsilyl trifluoromethanesulfonate

The iodotrimethylsilane-catalyzed reaction of silyl enol ethers with aminomethyl ethers in acetonitrile gives aminomethylation products of the corresponding ketones readily. The reaction can slso be catalyzed by trimethylsilyl trifluoromethanesulfonate in dichloromethane.     

Regio- and stereodefined synthesis of trimethylsilyl enol ethers resulted from the isomerization of α-trimethylsilyl ketones

The isomerization of an α-trimethylsilyl ketone is lead to the corresponding trimethylsilyl enol ether with the enhanced regioselectivity by heating or by the assist of trimethylsilyl trifluoromethanesulfonate. The thermal reaction discloses a new regiodefined (E)-selective route to silyl enol ethers.     

Reaction of enol ethers with zinc carbenoid reagents. Cyclopropanation and subsequent isomerization to allylic ethers

The reactions of enol ethers (ROCC, R = alkyl, silyl) with zinc carbenoid reagents were found to give allylic ethers in several cases along with the expected cyclopropyl ethers. The ratio of these two products was highly dependent on the concentration of the reaction mixture. Thus, the selective formation of each product was conveniently attained by merely changing the amounts of the solvent used. Zinc iodide, a by-product of the reaction, plays a key role in the present cyclopropyl to allylic rearrangement. Ring-opened ionic intermediates are proposed.     

Reaction of chloro-arylthio adducts of 1,1-dimethylallene with trimethylsilyl enol ethers—A method of 2-arylthioprenylation of carbonyl compounds

Conclusions The adduct of 1,1-dimethylallene with arylsulfenyl chlorides can be used to introduce the 2-aryltyioprenyl residue into molecules of carbonyl compounds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 392–395, February, 1985.     

Aldol-type reactions between trimethylsilyl enol ethers and acetals with the aid of rhodium complex

Aldol-type reactions of trimethylsilyl enol ethers with acetals, ketals, and orthoesters are successfully performed with the aid of a catalytic amount of rhodium complex, Rh₄(CO)₁₂ or [Rh(COD)(DPPB)]⁺ClO₄⁻, underneutral conditions.     

Phosphonyl radical addition to enol ethers. The stereoselective synthesis of cyclic ethers

Addition of diethyl phosphite or diethyl thiophosphite to enol ethers, in the presence of a radical initiator, results in the regioselective synthesis of organophosphonate or phosphonothioate derivatives, respectively, under mild conditions. This method can be applied to the stereoselective formation of substituted tetrahydrofurans and tetrahydropyrans, on cyclisation of vinyl ethers bearing unsaturated side chains.     

Synthesis of 1,4-diketones by the coupling reaction of trimethylsilyl enol ethers with lead tetraacetate

Synthesis of 1,4-diketones in good yields was achieved by the coupling reaction of the trimethylsilyl enol ethers of acetophenone, thiophene or furan with lead tetraacetate in dry dichloromethane and tetrahydrofuran at −78°C.     

Reaction of enol ethers with alkynes catalyzed by transition metals: 5-exo-dig versus 6-endo-dig cyclizations via cyclopropyl platinum or gold carbene complexes

The intramolecular reaction of enol ethers with alkynes in methanol is catalyzed by electrophilic Pt(II), Pd(II), and Au(III) chlorides and by a Cu(I) complex to give five- or six-membered rings bearing dimethyl acetals. The reaction takes place by an anti addition of the enol ether and the metal to the alkyne. The possible involvement of vinylidene complexes in this reaction is excluded. In addition to the usual 5-exo-dig (or 6-exo-dig) pathways, a 6-endo-dig pathway has also been found to take place with certain enynes. One case of 5-endo-dig cyclization has also been found. A general scheme for the alkoxycyclization of enynes catalyzed by transition metals based on DFT calculation of PtCl(2) and AuCl(3) complexes that includes exo and endo cyclizations is presented.     

Carbazole synthesis via an in situ trapping strategy with indolyl enol ethers

Indolyl enol ethers, generated from the alkoxy(indolyl)carbenium tetrafluoroborates 1 by treatment with sodium hydride, can be trapped with dimethyl acetylenedicarboxylate or N-phenylmaleimide to furnish the selectively functionalized carbazoles 3,4,5,9,10 , and 13. In addition, the biaryl derivatives 6 and 11 are produced by a ring-opening reaction of the primarily formed Diels-Alder adduct. In the case of the biaryl derivative 6 , an X-ray crystal structure analysis yields valuable information on constitutions and configurations in the biaryl series. The phenomenon of atropisomerism is discussed for this compound.