Surface tension, fluorescence, and dynamic light scattering were used to investigate the properties of a binary surfactant system comprising an anionic gemini surfactant (DLMC) and cationic gemini surfactant (II‐12‐EO2). Surface tension measurements afforded the critical micelle concentration (cmc) of the mixture and the values are all lower than those of pure constituent surfactants. For the mixtures of II‐12‐EO2/DLMC, the micelle aggregation number decreases with the increase of II‐12‐EO2, and the micropolarity of the micelle is lowest when the molar fraction of II‐12‐EO2 is 0.5; the hydrodynamic radius (Rh) of the mixed micelle first increases and then decreases with the addition of II‐12‐EO2, and larger micelles are obtained when the molar fraction of II‐12‐EO2 is 0.5 or 0.7. 相似文献
An enantioselective one‐pot Michael/Michael/Henry/hemiacetalization reaction between α,β‐unsaturated aldehydes, α‐ketoamides, and nitroalkenes under mild conditions catalyzed by a diarylprolinol silyl ether has been developed. The sequential methodology provides a direct approach to a wide range of fully substituted chiral oxabicyclo[2.2.2]octanes with seven contiguous stereocenters in moderate to excellent yields (up to 99%), high to excellent diastereoselectivities (up to >25:1 dr), and high to excellent enantioselectivities (up to 99% ee).
An operationally simple and efficient copper‐catalyzed three‐component tandem reaction of terminal alkynes, diazo compounds and amines to yield β‐enamino esters is described. This straightforward protocol takes place rapidly with a wide range of substrates and gives the desired β‐enamino esters in good to excellent yields. Preliminary mechanistic studies suggested that the reaction probably proceeds through Cu‐catalyzed formal C–H insertion to produce an alkynoate intermediate, which was then trapped by amines to give the β‐enamino esters.
