A method for asymmetric and site selective annulations at the γ and γ′ positions of cyclic 2‐enones with α,β‐unsaturated aldehydes has been developed. The organocatalysed [3+3]‐annulations proceed with high levels of regio‐, diastereo‐, and enantioselectivity, affording a series of high value fused carbocycles. Further elaboration gave key lactones (both bridged and fused).
Yb(OTf)3-Promoted ZnCl2-Catalyzed Conia-Ene Reaction of Linear β-Alkynic β-Dicarbonyls
作者:Jin-Heng Li、Yu Liu、Ren-Jie Song
DOI:10.1055/s-0030-1258213
日期:2010.11
An atom-economical and solvent-freeytterbium(III) triflate promoted, zinc(II) chloride catalyzed Conia-ene method has been developed for the construction of five- to six-membered-ring carbocycles. In the presence of zinc(II) chloride and ytterbium(III) triflate, a variety of linear β-alkynic β-keto esters and β-alkynic β-diketones were cyclized under neat conditions in moderate to good yields. It
The facile dearomatization of nitroaromatic compounds using lithium enolates of unsaturated ketones in conjugate additions and (4+2) formal cycloadditions
conventional nitroarenes by lithiated enolates derived from methyl vinyl ketones easily takes place, following a formal (4+2) cycloaddition process. While nitroindoles react readily with in situ generated conjugated enolates, the deaggregation of these latter species using HMPA extends the reaction scope to the more aromatic nitronaphthalenes and pyridines.