Ruthenium-Catalyzed Cycloisomerization−6π-Cyclization: A Novel Route to Pyridines
摘要:
Herein we report a method for the synthesis of substituted pyridines. The unsaturated ketones and aldehydes derived from the cycloisomerization of primary and secondary propargyl diynols in the presence of [CpRu(CH3CN)(3)]PF6 (1) are converted to 1-azatrienes which in turn undergo a subsequent electrocyclization-dehydration to provide pyridines with excellent regiocontrol.
Cobalt cyclopentadienyl complexes incorporating a fumarate and a CO ligand (see picture) efficiently catalyze inter‐ and intramolecular [2+2+2] cycloadditions of alkynes, nitriles, and/or alkenes to give benzenes, pyridines, or 1,3‐cyclohexadienes. Unlike catalysts such as [CpCo(CO)2] or [CpCo(C2H4)2] (Cp=C5H5), they are air‐stable, easy to handle, compatible with microwave conditions, and do not necessarily
结合富马酸酯和CO配体的环戊二烯钴复合物(见图)有效地催化炔烃,腈和/或烯烃的分子间和分子内[2 + 2 + 2]环加成反应,从而生成苯,吡啶或1,3-环己二烯。与[CpCo(CO)2 ]或[CpCo(C 2 H 4)2 ](Cp = C 5 H 5)等催化剂不同,它们具有空气稳定性,易于处理,与微波条件兼容,并且不一定需要辐射才能活跃。
A new approach to pyridines through the reactions of methyl ketones with 1,2,4-triazines
作者:Shu-Wen Wang、Wei-Si Guo、Li-Rong Wen、Ming Li
DOI:10.1039/c4ra11294f
日期:——
A new route to prepare pyridine derivatives based on inverse electron demand Diels–Alder/retro-Diels–Alder reactions of ketones with 1,2,4-triazines is reported. It is the first time using methylketones directly as a dienophile to react with 1,2,4-triazines without enamine intermediates, which is complementary to the classical Boger reaction.
their reactivity in [2+2+2] cycloaddition reactions compared with highly active [CpCo(H2CCHSiMe3)2] (1). Whereas 1 is an excellent precursor for the synthesis of [CpCo(olefin)(phosphite)] complexes (2 a–f), [CpCo(phosphite)2] complexes (3 a–e) were prepared photochemically from [CpCo(cod)]. The complexes were evaluated in the cyclotrimerization reaction of diynes with nitriles yielding pyridines. For
were demonstrated in [2+2+2] cycloaddition reactions of different diynes with nitriles, yielding the substituted isoquinoline derivatives with good yields within short reaction times and under very mild conditions. The presented complexes show higher activities compared to [CpCo(COD)] (3) while possessing advantages in preparation and handling compared to [CpCo(H2C═CH2)2] (4).
A Dramatic Substituent Effect in Silver(I)-Catalyzed Regioselective Cyclization of ortho-Alkynylaryl Aldehyde Oxime Derivatives
作者:Hongyin Gao、Junliang Zhang
DOI:10.1002/adsc.200800568
日期:2009.1
A dramatic substituent effect was found in the silver(I)-catalyzed cyclization reaction of ortho-alkynylaryl aldehyde oximederivatives. When R is an alkyl group, the Ag(I)-catalyzed reaction in dimethylacetamide at 110 °C (conditions A) affords isoquinolines in good to excellent yields, in contrast, isoquinolin-1(2 H)-ones were produced in moderate to high yields under conditions B (dimethylformamide