One‐Pot Synthesis of New Imidazo[1,2‐a]pyridine and Imidazo[1,2‐a]pyrimidine Derivatives.

Abstract

Ring closure reactions O 0130 One-Pot Synthesis of New Imidazo[1,2-a]pyridine and Imidazo[1,2-a]pyrimidine Derivatives. -The new title heterocycles (IV) are easily obtained by a two-step one-pot procedure. -(GEORGESCU*, F.; GEORGESCU, E.; DRAGHICI, C.; IUHAS, P. C.; FILIP, P. I.; Rev. Roum. Chim. 50 (2005) 5, 349-352; S.C. OLTCHIM Res. Cent., RO-1000 Ramnicu-Valcea, Rom.; Eng.) -H. Haber 12-043

Pyrrolo[1,2-b]pyridazines. A revisit

“…One of the most useful methods for obtaining pyrrolopyridazine derivatives is the 1,3-dipolar cycloaddition between pyridazinium N-ylides and activated olefinic or acetylenic dipolarophiles. The synthesis of pyrrolo[1,2-b]pyridazines through 1,3-dipolar cycloadditions has been described in over 35 papers, using acetylenic, [68][69][70][71][72][73][74][75][76][77][78][79][80] olefinic, [80][81][82][83][84][85][86][87][88][89][90][91][92] as well as both acetylenic and olefinic dipolarophiles. [93][94][95][96][97][98][99][100][101][102][103] The advantages of the method consist of: a) the availability of the raw material, as pyridazinium salts are easily obtained from pyridazine or its derivatives and halogenated derivatives, and b) the pyridazinium N-ylide generation and the cycloaddition are performed "one-pot", and the cycloaddition does not require special reaction conditions.…”

Structure–activity relationship study of EphB3 receptor tyrosine kinase inhibitors

“…5-Bromo-2-nitropyridine, 19 , was treated with piperidine to give 20 , which was subsequently hydrogenated in the presence of 10% Pd/C to yield 21 . The 2-aminopyridines 18 or 21 were heated at reflux in toluene with N,N -dimethylformamide dimethyl acetal (DMF-DMA) and then treated with 2-bromo-N-arylacetamides (prepared by coupling anilines with 2-bromoacetyl chloride) to give 22 19. β-Ketoamide 23 was chlorinated with sulfuryl chloride yielding 24 , which was used without purification.…”

“…Amine 17 was also converted to intermediate 28 ,20 which was not isolated, but subjected to halogen metal exchange with n -BuLi followed by addition of N -Boc-4-piperidone to give 29 after an acidic work-up. Both 27 and 29 were converted to 30 and 31 , respectively, utilizing the procedure described in Method E 19. Finally, removal of the carbamate protecting groups from 30 and 31 with 30% TFA in dichloromethane produced amines 32 and 33 , respectively.…”