The novel cyclization/fluorinationreaction of N-dienes in superacid was extended to substituted substrates. The influence of the substitution on superelectrophilic character of dicationic intermediates was shown and its dramatic effect on the synthesis of fluoropiperidines was studied. On the basis of new dicationic α-chloronium ammonium intermediates, starting from halogen-substituted dienes, high-valued
Efficient Oxidative Cyclization of 1,6-Dienes: A Highly Diastereoselective Entry to Substituted Tetrahydropyrans
作者:Stefanie Roth、Christian B. W. Stark
DOI:10.1002/anie.200504572
日期:2006.9.18
Highly regioselective synthesis of N-acyl-2,3-dihydropyrrole or N-sulfonyl-2,3-dihydropyrrole derivatives by nano-palladium catalyzed cycloisomerization of 1,6-dienes
作者:Lizhe Feng、Zhiyong Gan、Xiaopeng Nie、Peipei Sun、Jianchun Bao
DOI:10.1016/j.catcom.2009.12.018
日期:2010.2
Porous palladium nanoparticles were prepared using a solution-phase approach. Their structures and shapes were analyzed by XRD, EDS, TEM and HRTEM. These palladium nanoparticles were used to catalyze the cycloisomerization reaction of N,N-diallylamide or N,N-diallylsulfonamide, and N-acyl-23-dihydropyrrole or N-sulfonyl-2,3-dihydropyrrole derivatives were therefore synthesized with very high regioselectivity, and in good yields. The nano-palladium catalyst showed high efficiency and it can be reused several times. A hydropalladation mechanism was proposed for this reaction. (C) 2009 Published by Elsevier B.V.