1-Azaallylic Anions in Heterocyclic Chemistry

Insight into the Solvation and Isomerization of 3‐Halo‐1‐azaallylic Anions from Ab Initio Metadynamics Calculations and NMR Experiments

“…Since their first use in the early 1960s, [1][2][3] non-halogenated 1-azaallylic anions have gained a predominant role in organic synthesis due to their ability to form new CÀC bonds with a lack of side products. [4] The chemistry of 1-azaallylic anions leads to basic heterocyclic systems such as aziridines, azetidines, pyrrolidines, pyrroles, piperidines, oxiranes, oxolanes, and higher functionalized ring systems, currently of interest for pharmaceutical chemistry and agrochemistry. The application of certain halogenated counterparts, that is, the 3-chloro-3-methyl-1-azaallylic anions, in particular by the group of De Kimpe and more general by the group of Florio, which incorporated the 3-chloro-3-methyl-1-azaallylic moiety into heterocyclic structures, has led to the synthesis of various important classes of compounds such as cyclopropanes, [5] tetrahydrofurans, [6] tetrahydropyrans, [6c] oxiranes, [7] aziridines, [7b,d, 8] chloroimines, [9] pyrroles and pyridines, [10] steroids, [11] alkenylheterocycles, [12] and oxazetidines.…”

Diverse Reactions of 1,4‐Dilithio‐1,3‐dienes with Nitriles: Facile Access to Tricyclic Δ1‐Bipyrrolines, Multiply Substituted Pyridines, Siloles, and (Z,Z)‐Dienylsilanes by Tuning of Substituents on the Butadienyl Skeleton

“…The subsequent double 5-exo lithiation/cyclization of 10 proceeds in an intramolecular manner to give tricyclic D 1 -bipyrroline 9 via protonolysis of 1-azaallylic dianion 11. [16] Deuterated tricyclic D 1 -bipyrroline 9 aD was isolated in 85 % yield with slightly less than two deuterium We recently reported that lithiation of 1-bromo-4-trisubstituted silyl-1,3-butadiene derivatives with tBuLi gave substituted siloles in high yields. [17] We also described the facile synthesis of lithio siloles from silyl 1,4-dilithio-1,3-butadiene derivatives.…”

One-pot regioselective synthesis of new 5-(arylsulfonylamino)imidazo[2,1-b]thiazoles

“…[1][2][3][4][5][6][7][8][9][10][11][12] Moreover, besides the carbon atom of azomethine group,-haloimines contain another electrophilic reactive site, namely the carbon atom of the polyhalomethyl group. Thus, these compounds are promising dielectrophiles that can be used as key reagents in the preparation of amidines, 7 biologically active amino acids, 9 and heterocycles.…”

“…The reaction is performed under argon in CCl 4 . Reagent addition order is important: when N,N-dichloroamide is added to a solution of phenylacetylene, the yields of imines are substantially higher than when the reagents are mixed in the reverse order (90-95 vs. 40-64%).…”