Disclosed is a compound of the formula (I): wherein R.sub.3, R.sub.6a and R.sub.8 are the same or different and represent a C.sub.2-8 alkyl which is unbranched or branched and unsubstituted or substituted; C.sub.3-8 cycloalkyl which is unsubstituted or substituted; C.sub.4-8 cycloalkylalkyl wherein the cycloalkyl portion is unsubstituted or substituted; aryl which is unsubstituted or substituted; aralkyl C.sub.1-4 ; heterocyclyl; and heterocyclylalkyl (C.sub.1 -C.sub.4) R.sub.6b represents H or R.sub.6a, or together R.sub.6b, N, and R.sub.6a make a C.sub.3 -C.sub.8 ring containing from one to three nitrogen atoms, from zero to two oxygen atoms, from zero to two sulfur atoms, which is optionally substituted; and where aryl is phenyl or naphthyl, the heterocyclyl is a 5, 6 or 7 membered ring including from one to three nitrogen atoms, and from zero to two oxygen atoms, from zero to two sulfur atoms, and can be substituted as in aryl on the carbons or nitrogens of that ring; or a pharmaceutically acceptable salt thereof.
本发明揭示了一种化合物的结构式(I):其中,R.sub.3、R.sub.6a和R.sub.8相同或不同,表示未支链或支链的C.sub.2-8烷基,未取代或取代;未取代或取代的C.sub.3-8环烷基;未取代或取代的C.sub.4-8环烷基烷基,其中环烷基部分未取代或取代;未取代或取代的芳基;未取代或取代的芳基烷基C.sub.1-4;杂环烷基;和杂环烷基烷基(C.sub.1-C.sub.4);R.sub.6b表示H或R.sub.6a,或者R.sub.6b,N和R.sub.6a共同构成一个含有从1到3个氮原子,从0到2个氧原子,从0到2个
硫原子的C.sub.3-C.sub.8环,该环可以选择性地被取代;其中,苯基或
萘基的芳杂环为5、6或7成员环,包括从1到3个氮原子和从0到2个氧原子、从0到2个
硫原子,并且可以在该环的碳或氮上像芳基一样被取代;或其药学上可接受的盐。