. . "ach R3 independently is an alkyl group, a cycloalkyl group, a heterocycloalkyl group, an aryl group, or a heteroaryl group; or a group of formula 10 wherein R4 and each R5 independently are an alkyl group, a cycloalkyl group, a heterocycloalkyl group, an aryl group, or a heteroaryl group; and to pharmaceutically acceptable salts and solvates thereof." . . .