107941-60-6Relevant articles and documents
Specific Z-Selectivity in the Oxidative Isomerization of Allyl Ethers to Generate Geometrically Defined Z-Enol Ethers Using a Cobalt(II)(salen) Complex Catalyst
Huang, Guanxin,Ke, Miaolin,Tao, Yuan,Chen, Fener
, p. 5321 - 5329 (2020)
Enol ether structural motifs exist in many highly oxygenated biologically active natural products and pharmaceuticals. The synthesis of the geometrically less stable Z-enol ethers is challenging. An efficient Z-selective oxidative isomerization process of allyl ethers catalyzed by a cobalt(II) (salen) complex using N-fluoro-2,4,6-trimethylpyridinium trifluoromethanesulfonate (Me3NFPY?OTf) as an oxidant has been developed. Thermodynamically less stable Z-enol ethers were prepared in excellent yields with high geometric control. This methodology also demonstrates the effectiveness in controlling the Z-selective isomerization reaction of diallyl ethers at room temperature. This catalytic system provides an alternative pathway to extend the traditional reductive isomerization of allyl ethers.
In situ generated bulky palladium hydride complexes as catalysts for the efficient isomerization of olefins. Selective transformation of terminal alkenes to 2-alkenes
Gauthier, Delphine,Lindhardt, Anders T.,Olsen, Esben P. K.,Overgaard, Jacob,Skrydstrup, Troels
supporting information; experimental part, p. 7998 - 8009 (2010/08/04)
Application of an in situ generated bulky palladium(II) hydride catalyst obtained from a 1:1:1 mixture of Pd(dba)2, P(tBu)3, and isobutyryl chloride provides an efficient protocol for the isomerization and migration of a variety of olefins. In addition to the isomerization of (Z)- to (E)-olefins, the conjugative migration of allylbenzenes, allyl ethers, and amines was effectively achieved in near-quantitative yields and with excellent functional group tolerance. Catalyst loadings in the range of 0.5-1.0 mol % were typically applied, but even loadings as low as 0.25 mol % could be achieved when the reactions were performed under neat conditions. More interestingly, the investigated catalyst proved to be selective for converting terminal alkenes to 2-alkenes. This one-carbon migration process for monosubstituted olefins provides an alternative catalyst, which bridges the gap between the allylation and propenylation/vinylation protocols. Several substrates, including homoallylic alcohols and amines, were selectively transformed into their corresponding 2-alkenes, and examples using enantiomerically enriched substrates provided products without epimerization at the allylic stereogenic carbon centers. Finally, some mechanistic investigations were undertaken to understand the nature of the active in situ generated Pd-H catalyst. These studies revealed that the catalytic system is highly dependent on the large steric demand of the P(tBu)3 ligand. The use of an alternative ligand, cataCXium PinCy, also proved effective for generating an active catalyst, and it was demonstrated in some cases to display better selectivity for the one-carbon shifts of terminal olefins. A possible intermediate involved in the preparation of the active catalyst was characterized by its single-crystal X-ray structure, which revealed a monomeric tricoordinated palladium(II) acyl complex, bearing a chloride ligand.
Convenient synthesis of isoxazolines via tandem isomerization of allyl compounds to vinylic derivatives and 1,3-dipolar cycloaddition of nitrile oxides to the vinylic compounds
Krompiec, Stanis?aw,Bujak, Piotr,Szczepankiewicz, Wojciech
supporting information; experimental part, p. 6071 - 6074 (2009/04/11)
A novel effective method for the synthesis of new isoxazolines via tandem isomerization of QCH(X)CH{double bond, long}CH(Y) to QC(X){double bond, long}CHCH2(Y) (Q = RO, RS, R2N, R3Si, etc.; X = H, R, OR; Y = H, R; R = alkyl, aryl) catalyzed by ruthenium complexes and 1,3-dipolar cycloaddition of the latter compounds to arenenitrile oxides is presented. The cycloaddition of QCH(X)CH{double bond, long}CH(Y) to 2,6-dichlorobenzonitrile oxide is also described. The regio- and stereoselectivity of the cycloaddition of nitrile oxide to allyl and 1-propenyl (vinylic in general) compounds is discussed.
