856698-58-3Relevant articles and documents
Preparation of tricyclic imidazopyridines by asymmetric ketone hydrogenation in the presence of RuCl2[(S)-Xyl-P-Phos][(S)-DAIPEN]
Palmer, Andreas Marc,Zanotti-Gerosa, Antonio,Nedden, Hans
, p. 1310 - 1327 (2008/12/20)
The novel complex RuCl2[(S)-Xyl-P-Phos][(S)-DAIPEN] was identified as a highly active catalyst for the asymmetric reduction of a variety of prochiral ketones possessing an imidazo[1,2-a]pyridine scaffold. The corresponding alcohols were obtained in excellent enantiomeric purities (>96% ee) and served as valuable intermediates for the synthesis of pharmacologically active 7H-8,9-dihydropyrano[2,3-c]imidazo[1,2-a]pyridines. The complexity of these multi-functional substrates required the development of specific reaction conditions. Whereas the reduction with RuCl2[PP][NN] catalysts (Noyori catalysts) has never been reported to occur under aqueous conditions, in the present case, the use of aqueous isopropanol or tert-butanol was not only tolerated, but also turned out to be beneficial, especially when the reduction was conducted at high substrate to catalyst (S/C) ratios.
Synthesis and evaluation of 7H-8,9-dihydropyrano[2,3-c]imidazo[1,2-a] pyridines as potassium-competitive acid blockers
Palmer, Andreas M.,Grobbel, Burkhard,Jecke, Cornelia,Brehm, Christof,Zimmermann, Peter J.,Buhr, Wilm,Feth, Martin P.,Simon, Wolfgang-Alexander,Kromer, Wolfgang
, p. 6240 - 6264 (2008/03/27)
7H-8,9-Dihydropyrano[2,3-c]imidazo[1,2-a]pyridines with excellent physicochemical and pharmacological properties were identified that represent interesting candidates for further development as potassium-competitive acid blockers (P-CABs). The title compounds were prepared following synthetic pathways that relied either on a Claisen rearrangement/cross-metathesis reaction or on the (asymmetric) reduction of prochiral ketones. The influence of the character of the substituents R3, R6, and Ar on the biological activity and the physicochemical properties of the target compounds was examined. In contrast to the parent system (R6 = H), compounds in which R6 represents a carboxamide residue generally show improved in vivo activity and favorable pKa/log D values. Whereas variation of R3 is useful to obtain target compounds with modified basicity and lipophilicity, strong inhibition of the H+/K+-ATPase and potent in vivo activity is observed for R3 = methyl only. Small modifications of the aryl group, e.g., replacement of hydrogen versus a fluoro atom or a methyl group, are allowed. The (9S)-enantiomers are responsible for the gastric acid secretion inhibiting action, whereas the (9R)-enantiomers are virtually inactive.
