Imidazo(1,2-a)pyridines. II. Ozonolysis of Imidazo(1,2-a)pyridines and Synthesis of Cardiotonic Agents.
作者:Motosuke YAMANAKA、Shinji SUDA、Naoki YONEDA、Hideto OHHRA
DOI:10.1248/cpb.40.666
日期:——
The metabolite of loprinone (E-1020) in dogs, 5-(2-aminopyridin-5-yl)-1, 2-dihydro-6-methyl-2-oxo-3-pyridine-carbonitrile (9), was prepared via ozonolysis of imidazo[1, 2-α]pyridinylpyridines and evaluated for positive inotropic activity. Its potency was less than that of loprinone and milrinone. Among compounds related to loprinone which were synthesized using the versatile intermediates (10a, b) obtained during the preparation of 9, only 5-(2-aminoimidazo[1, 2-α]pyridin-6-yl)-1, 2-dihydro-6-methyl-2-oxo-3-pyridinecarbonitrile (27) retained the activity of loprinone. The electron-withdrawing substituents at hte 2-position of imidazo[1, 2-α]pyridine reduced the activity of the parent compound.The ozonolysis of imidazo[1, 2-α]pyridine derivatives under neutral confitions afforded 2-acylaminopyridine derivatives in a 30-55% yield independent of the substituents at the 2-position of imidazo[1, 2-α]pyridine. It is possible to use imidazo[1, 2-α]pyridine as protected 2-aminopyridines, and 2, 3-unsubstituted imidazo[1, 2-α]pyridines are convenient for that purpose from the viewpoint of ease of preparation of the starting material.
犬中的洛普利酮(E-1020)代谢物,5-(2-氨基吡啶-5-基)-1,2-二氢-6-甲基-2-氧代-3-吡啶碳腈(9),通过咪唑并[1,2-α]吡啶吡啶的臭氧化制备,并评估了其正性肌力活性。其效力小于洛普利酮和米力农。在利用在制备9过程中获得的通用中间体(10a,b)合成的与洛普利酮相关的化合物中,只有5-(2-氨基咪唑并[1,2-α]吡啶-6-基)-1,2-二氢-6-甲基-2-氧代-3-吡啶碳腈(27)保留了洛普利酮的活性。咪唑并[1,2-α]吡啶2-位的吸电子取代基降低了母体化合物的活性。在中性条件下,咪唑并[1,2-α]吡啶衍生物的臭氧化反应提供了2-酰胺基吡啶衍生物,产率为30-55%,与咪唑并[1,2-α]吡啶2-位的取代基无关。有可能使用咪唑并[1,2-α]吡啶作为保护的2-氨基吡啶,从起始物料制备的便利性角度来看,未取代的2,3-咪唑并[1,2-α]吡啶是方便的。