Tandem Transformations of Nitriles into N-Heterocyclic Compounds by Electrophilic Trapping of Blaise Reaction Intermediates
作者:Hyunik Shin、Sang-gi Lee、Ju Kim、Yu Chun
DOI:10.1055/s-0031-1290814
日期:2012.6
Tandem transformations of nitriles into various N-heterocycles have been accomplished through the reaction of electrophiles with Blaise reaction intermediates formed in situ. The reaction of the Blaise reaction intermediates with propiolates gives 2-pyridones through consecutive C- and N-nucleophilic reactions. The tandem reactions of the Blaise reaction intermediate with 1,3-enynes proceed through C-nucleophilic addition followed by an electrocyclization-aromatization cascade to give pyridines. Exocyclic enamino esters can be prepared by transformations of omega-chloroalkyl nitriles through chemoselective intramolecular alkylation of the Blaise reaction intermediate. Palladium-catalyzed intramolecular arylations or copper-catalyzed intermolecular cross-coupling reactions of the Blaise reaction intermediate give a range of indole derivatives. Combinations of tandem alkylations and palladium-catalyzed couplings of the Blaise reaction intermediates of omega-chloroalkyl nitriles give N-fused indoles.
Chemoselective Intramolecular Alkylation of the Blaise Reaction Intermediates: Tandem One-Pot Synthesis of <i>exo</i>-Cyclic Enaminoesters and Their Applications toward the Synthesis of <i>N</i>-Heterocyclic Compounds
作者:Ju Hyun Kim、Hyunik Shin、Sang-gi Lee
DOI:10.1021/jo201964a
日期:2012.2.3
The intramolecular alkylative reactivity and N/C selectivity of the various Blaise reaction intermediates, which are formed from the reaction of the Reformatsky reagents with omega-chloroalkyl nitriles, did not reach the synthetic potential as an entry to exo-cyclic enaminoesters. To circumvent this issue, various additives were investigated, among which the addition of NaHMDS dramatically enhanced the reactivity and N/C selectivity. This modification provided a highly efficient route for the synthesis of various N-fused heterocyclic compounds, as it requires only two steps from nitriles.
Tandem One-Pot Construction of Indoles via Palladium and Copper-Catalyzed Coupling Reactions of the Blaise Reaction Intermediate
作者:Sang-gi Lee、Ju Kim
DOI:10.1055/s-0031-1289753
日期:2012.5
Chemoselective Intramolecular N-Alkylation/Palladium-Catalyzed C-N CouplingReaction of the Blaise Reaction Intermediate 2.3 Copper-Catalyzed Intermolecular N-C/C-C CouplingReaction of the Blaise Reaction Intermediate with 1,2-Dihaloarenes 3 Conclusion tandem reaction - Blaise reaction - palladium - copper - coupling - indoles