Regioselective formation of 2-alkoxyoxetanes in the photoreaction of aromatic carbonyl compounds with β,β-dimethyl ketene silyl acetals: notable solvent and silyl group effects
A Powerful Chiral Counteranion Motif for Asymmetric Catalysis
作者:Pilar García-García、Frank Lay、Patricia García-García、Constantinos Rabalakos、Benjamin List
DOI:10.1002/anie.200901768
日期:2009.6.2
Room to swing a cat: A chiral disulfonimide has been designed as a powerful new motif for asymmetriccatalysis. As a first illustration, a highly efficient and enantioselective Mukaiyama aldol reaction has been developed (see scheme). The actual catalyst is proposed to be an N‐silyl imide which is generated in situ.
A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both aldehydes and acetals with silylenolethers or ketene silylacetals to give the corresponding aldol adducts in moderate to high yields. The remarkable high catalytic activity of Al-MCM-41 over amorphous silica-alumina and aluminum-free mesoporous silicate was observed in the reaction
Polymer-supported PPh<sub>3</sub> as a reusable organocatalyst for the Mukaiyama aldol and Mannich reaction
作者:Satoru Matsukawa、Kazuki Fukazawa、Junya Kimura
DOI:10.1039/c4ra03394a
日期:——
An easily accessible and user-friendly polymer-supported phosphine PS-PPh3 catalyzes the aldol reaction of aldehydes and imines. A broad range of aldehydes and imines could be applied under mild conditions using 5–10 mol% PS-PPh3. PS-PPh3 was easily recovered and reused with minimal loss of activity.
Air- and water-stable Lewis acids: synthesis and reactivity of P-trifluoromethyl electrophilic phosphonium cations
作者:V. Fasano、J. H. W. LaFortune、J. M. Bayne、M. J. Ingleson、D. W. Stephan
DOI:10.1039/c7cc09128a
日期:——
A new class of electrophilic phosphoniumcations (EPCs) containing a –CF3 group attached to the phosphorus(V) center is readily accessible in high yields, via a scalable process. These species are stable to air, water, alcohol and strong Brønsted acid, even at raised temperatures. Thus, P–CF3 EPCs are more robust than previously reported EPCs containing P–X moieties (X = F, Cl, OR), and despite their
AbstractWe report the synthesis of a chiral dendralenic C–H acid, which contains three unsubstituted binaphthyl moieties. This motif and an achiral variant can be made from their corresponding bis(sulfone) precursors in onestep. Despite the presence of the enantiopure binaphthyl backbone, the newly designed chiral C–H acid showed only poor enantioselectivity in a Mukaiyama aldolreaction. First attempts