Substituent effects in the aliphatic Claisen rearrangement of substituted (1-methyl-3-oxahexa-1,5-dienyl)amines: synthesis of substituted 2-aminopent-4-enals. Alternative [1,3]-sigmatropic shifts in related aromatic systems
N,N-Dimethylaminobenzoates enable highly enantioselective Sharpless dihydroxylations of 1,1-disubstituted alkenes
作者:Yaohong Zhao、Xiangyou Xing、Shaolong Zhang、David Zhigang Wang
DOI:10.1039/c4ob00621f
日期:——
beneficial catalyst–substrate π–π stacking electronic interactions in the classical Sharpless asymmetric dihydroxylations (SAD) leads to the identification of highly polarizable allylic N,N-dimethylaminobenzoate as a remarkably efficient auxiliary for inducing high levels of enantioselectivities (up to 99% ee) in the traditionally challenging substrate class of 1,1-disubstituted aliphatic alkenes.
An efficient, and mild synthetic route for the preparation of functionalized volatile oxa-bicyclo[4.1.0]-hept-4-ene (29 compounds, 44–98% isolated yields) has been developed relying on the association of IPrAuCl with NaBArF. The remarkable selectivity was demonstrated on a 1 g and 25 g scale with low catalyst loadings. The synthetic utility of these low-molecular-weight enols was further demonstrated
ethers. Several bicyclic adducts were prepared in good to excellent yields (18–99%). Evaluation of NHC–Au complexes allowed to reach a TOF of 300 h–1. The evaluation for the organoleptic properties of [4.1.0]-bicyclic ethers were compared with the unprecedented properties of the 1,6-enyne precursors. Evaluations of starting materials showed a great interest in these structures with various olfactory facets
Rhodium‐Catalyzed Asymmetric [2+2+2] Cycloaddition Reactions of 1,6‐Enynes and Oxabenzonorbornadienes
作者:Jianxiao Ni、Jingchao Chen、Yongyun Zhou、Gaowei Wang、Sida Li、Zhenxiu He、Weiqing Sun、Baomin Fan
DOI:10.1002/adsc.201900380
日期:2019.8.5
The asymmetric [2+2+2] cycloaddition reactions of 1,6‐enynes and oxabenzonorbornadienes was accomplished by using the complex of [Rh(COD)2]BF4 and (R)‐Xyl‐P‐Phos as chiral catalyst. A range of 1,6‐enynes and oxabenzonorbornadienes were well tolerated in the cycloaddition reaction, which afforded various polycyclic products with asymmetric quaternary carbon centers generally in excellent enantioselectivities
Regio- and stereo-specific addition of chlorodibutyltin hydride to prop-2-ynylic ethers
作者:Terence N. Mitchell、Said-Nadjib Moschref
DOI:10.1039/a802160k
日期:——
A number of prop-2-ynylic ethers smoothly undergo regio- and stereo-specific hydrostannation with chlorodibutyltin hydride in good to nearly quantitative yield at room temperature in benzene.