. "???Heteroaryl:??? refers to an aryl group wherein one or more of the ring carbon atoms is replaced with another atom such as N, O or S. Typical heteroaryl groups include, but are not limited to, furanyl, thienyl, indolyl, pyrrolyl, pyranyl, pyridyl, pyrimidyl, pyrazyl, pyridazyl, purine, pyrimidine and the like." . . .