Catalytic conversion of (β,γ-unsaturated esters, amides and nitriles into γ-alkoxy or γ-hydroxy α,β-unsaturated derivatives induced by persulfate anion oxidation of diphenyl diselenide
Synthesis of optically active γ-cyano-β, γ-epoxy alcohols and secondary γ-cyano allylic alcohols
作者:Isao Yamakawa、Hirokazu Urabe、Yuichi Kobayashi、Fumie Sato
DOI:10.1016/s0040-4039(00)78904-0
日期:1991.4
asymmetric epoxidation of 3-cyanoallyl alcohol (4-hydroxy-2-butenecarbonitrile, 6) afforded a potentially useful chiral building block, 3-cyano-2,3-epoxypropan-1-ol (7). Kinetic resolution of the secondary γ-cyano allylic alcohol (rac-3) provided an efficient method for synthesis of opticallyactive 3. The Epoxidation of opticallyactive 3 to γ-cyano-α,β-epoxy alcohol 5 was also reported.
The exchange of the PPh3 ligand in the complex [1,3-bis(2,6-dimethylphenyl)4,5-dihydroimidazol-2-ylidene](PPh3)(Cl)2RuCHPh (7) for a pyridine ligand at ambient temperature leads to the formation of the stable phosphine-free carbene ruthenium complex [1,3-bis(2,6-dimethylphenyl)4,5-dihydroimidazol-2-ylidene](C5H5N)2(Cl)2 RuCHPh (8). The resulted ruthenium complex exhibits highly catalytic activity for the cross metathesis of acrylonitrile with various functionalized olefins under mild conditions, and its activity can be further improved by the addition of a Lewis acid such as Ti(OiPr)4. In the mixture products, the Z-isomer predominates.
The carbene ruthenium complex [1,3-bis(2,6-dimethylphenyl)-4,5-dihydroimidazol-2-ylidene](C5H5N)2(Cl)2RuCHPh (8) was prepared by the reaction of [1,3-bis (2,6-dimethylphenyl)-4,5-dihydroimidazol-2-ylidene](PPh3)(Cl)2RuCHPh (7) with pyridine and used as a highly effective catalyst for the cross-metathesis of acrylonitrile with various functionalized olefins.
卡宾钌络合物[1,3-双(2,6-二甲基苯基)-4,5-二氢咪唑-2-亚烷基](C 5 H 5 N)2(Cl)2 RuCHPh(8)的制备[1,3-双(2,6-二甲基苯基)-4,5-二氢咪唑-2-亚烷基](PPh 3)(Cl)2 RuCHPh(7)与吡啶,用作交叉复分解的高效催化剂丙烯腈与各种官能化烯烃的混合物。
New Bicyclic Azalide Macrolides Obtained by Tandem Palladium Catalyzed Allylic Alkylation/Conjugated Addition Reaction
Unprecedented tandem allylic alkylation/intermolecular Michael addition was used in the preparation of novel bicyclic azalides. NMR spectroscopy was used not only to unambiguously determine and characterize the structures of these unexpected products of chemical reaction but also to investigate the effect the rigid bicyclic modification has on the conformation of the whole molecule. Thus, some of the
Chelation between gamma-hydroxy unsaturated nitriles and Grignard reagents promotes an otherwise difficult anionic conjugate addition reaction. The intermediate chelate is readily generated by deprotonation with t-BuMgCl followed by the addition of a second Grignard reagent that triggers an intramolecular conjugate addition. Structurally diverse Grignard reagents add with equal efficiency, providing an intermediate