Unusual<i>t</i>-BuLi Induced Ortholithiation versus Halogen-Lithium Exchange in Bromopyridines: Two Alternative Strategies for Functionalization
作者:Philippe Gros、Yves Fort、Philippe Pierrat
DOI:10.1055/s-2004-831337
日期:——
The reaction of lithiating agents with various 3-bromopyridines has been investigated. An unprecedented selectivity was observed with t-BuLi, which effected a clean lithiation at C-4. With 3-bromo and 2-chloro-3-bromo pyridines, the ortholithiation-exchange ratio was strongly electrophile and addition order dependent while 2-chloro-5-bromopyridine always gave exclusive C-4 substitution.
Triazolopyridines. Part 26: The preparation of novel [1,2,3]triazolo[1,5-a]pyridine sulfoxides
作者:Belén Abarca、Rafael Ballesteros、Rafael Ballesteros-Garrido、Françoise Colobert、Frédéric R. Leroux
DOI:10.1016/j.tet.2008.02.011
日期:2008.4
The regioselective synthesis of new triazolopyridine halides and sulfoxides with the substituent in all different ring positions of [1,2,3]triazolo[1,5-a]pyridines is presented. The triazolo ringopeningreaction of some representative sulfoxides to obtain disubstituted pyridines is also studied.
提出了在[1,2,3]三唑并[1,5- a ]吡啶的所有不同环位置具有取代基的新的三唑并吡啶卤化物和亚砜的区域选择性合成。还研究了一些代表性亚砜的三唑并开环反应,以获得二取代的吡啶。
Dialyzable Carbosilane Dendrimers as Soluble Supports for the Functionalization of Pyridine Fragments via Palladium-Catalyzed Coupling Reactions
作者:Jérôme Le Nôtre、Judith J. Firet、Leo A. J. M. Sliedregt、Bart J. van Steen、Gerard van Koten、Robertus J. M. Klein Gebbink
DOI:10.1021/ol0480776
日期:2005.2.1
[reaction: see text] The use of carbosilane (CS) dendrimers as soluble supports in liquid phase organic synthesis (LPOS) is described. Control of the three key steps is perfectly achieved by covalently binding a pyridine fragment to the soluble support, modifying it via coupling reactions, and releasing it at the end. Nanofiltration (dialysis) allows facile purification of the supported molecules after