Compounds of the formula I in which R 1 denotes A, -C(R 3)(R 4)-Ar, -C(R 3)(R 4)-Het or -C(R 3)(R 4)-Cyc, R 2, R 2a each, independently of one another, denote H, A, Hal, CN, -[C(R 3) 2] n -Ar', -[C(R 3) 2] n -Het', -[C(R 3) 2] n -Cyc, OR 3 or N(R 3) 2, R 3 denotes H or A, R 4 denotes H, A, -[C(R 3) 2] m OR 3, -[C(R 3) 2] m N(R 3) 2 or -[C(R 3) 2] m Het 1, A denotes unbranched or branched alkyl having 1-6 C atoms, in which one or two non-adjacent CH 2 groups may be replaced by O, N and/or S atoms and/or by -CH=CH-groups and/or, in addition, 1-7 H atoms may be replaced by F, Cyc denotes cycloalkyl having 3, 4, 5, 6 or 7 C atoms, Ar denotes phenyl which is unsubstituted or mono-, di- or trisubstituted by Hal, A, OR 3, N(R 3) 2, NO 2, CN, COOR 3, CON(R 3) 2, NR 3 COA, NR 3 SO 2 A, COR 3, SO 2 N(R 3) 2 and/or S n A, Ar' denotes phenyl which is unsubstituted or mono-, di- or trisubstituted by Hal, A, OR 3, N(R 3) 2, SR 3, NO 2, CN, COOR 3, CON(R 3) 2, NR 3 COA, NR 3 SO 2 A, SO 2 N(R 3) 2, S m A, CO-Het 1, Het 1, [C(R 3) 2] n N(R 3) 2, [C(R 3) 2] n Het 1, O[C(R 3) 2] n -N(R 3) 2, O[C(R 3) 2] n Het 1, NHCOOA, NHCON(R 3) 2, NHCOO[C(R 3) 2] n N(R 3) 2, NHCOO[C(R 3) 2]nHet 1, NHCONH[C(R 3) 2] n N(R 3) 2, NHCONH[C(R 3) 2] n Het 1, OCONH[C(R 3) 2] n N(R 3) 2, OCONH[C(R 3) 2] n Het 1, CO-Het 1, CHO and/or COA, Het denotes a mono- or bicyclic saturated, unsaturated or aromatic heterocycle having 1 to 4 N and/or O and/or S atoms which is unsubstituted or mono- or disubstituted by Hal, A, OR 3, N(R 3) 2, NO 2, CN, COOR 3, CON(R 3) 2, NR 3 COA, NR 3 SO 2 A, COR 3, SO 2 NR 3 and/or S n A, Het' denotes a mono-, bi- or tricyclic saturated, unsaturated or aromatic heterocycle having 1 to 4 N, O and/or S atoms, which is unsubstituted or may be mono- or disubstituted by Hal, A, OR 3, N(R 3) 2, SR 3, NO 2, CN, COOR 3, CON(R 3) 2, NR 3 COA, NR 3 SO 2 A, SO 2 N(R 3) 2, S m A, CO-Het 1, Het 1, [C(R 3)2] n N(R 3)2, [C(R 3) 2] n Het 1, O[C(R 3) 2] n N(R 3) 2, O[C(R 3) 2] n Het 1, NHCOOA, NHCON(R 3) 2, NHCOO[C(R 3) 2] n N(R 3) 2, NHCOO[C(R 3) 2] n Het 1, NHCONH[C(R 3) 2] n N(R 3) 2, NHCONH[C(R 3) 2] n Het 1, OCONH[C(R 3) 2] n N(R 3) 2, OCONH[C(R 3) 2] n Het 1, CO-Het 1, CHO, COA, =S, =NH, =NA and/or =O (carbonyl oxygen), Het 1 denotes a monocyclic saturated heterocycle having 1 to 2 N and/or O atoms, which may be mono- or disubstituted by A, OA, OH, Hal and/or =O (carbonyl oxygen), Hal denotes F, Cl, Br or I, n denotes 0, 1 or 2, m denotes 1 or 2, and pharmaceutically usable salts, tautomers and stereoisomers thereof, including mixtures thereof in all ratios. R 1 denotes A, -C(R 3)(R 4)-Ar, -C(R 3)(R 4)-Het or -C(R 3)(R 4)-Cyc, R 2, R 2a each, independently of one another, denote H, A, Hal, CN, -[C(R 3) 2] n -Ar', -[C(R 3) 2] n -Het', -[C(R 3) 2] n -Cyc, OR 3 or N(R 3) 2, R 3 denotes H or A, R 4 denotes H, A, -[C(R 3) 2] m OR 3, -[C(R 3) 2] m N(R 3) 2 or -[C(R 3) 2] m Het 1, A denotes unbranched or branched alkyl having 1-6 C atoms, in which one or two non-adjacent CH 2 groups may be replaced by O, N and/or S atoms and/or by -CH=CH-groups and/or, in addition, 1-7 H atoms may be replaced by F, Cyc denotes cycloalkyl having 3, 4, 5, 6 or 7 C atoms, Ar denotes phenyl which is unsubstituted or mono-, di- or trisubstituted by Hal, A, OR 3, N(R 3) 2, NO 2, CN, COOR 3, CON(R 3) 2, NR 3 COA, NR 3 SO 2 A, COR 3, SO 2 N(R 3) 2 and/or S n A, Ar' denotes phenyl which is unsubstituted or mono-, di- or trisubstituted by Hal, A, OR 3, N(R 3) 2, SR 3, NO 2, CN, COOR 3, CON(R 3) 2, NR 3 COA, NR 3 SO 2 A, SO 2 N(R 3) 2, S m A, CO-Het 1, Het 1, [C(R 3) 2] n N(R 3) 2, [C(R 3) 2] n Het 1, O[C(R 3) 2] n -N(R 3) 2, O[C(R 3) 2] n Het 1, NHCOOA, NHCON(R 3) 2, NHCOO[C(R 3) 2] n N(R 3) 2, NHCOO[C(R 3) 2]nHet 1, NHCONH[C(R 3) 2] n N(R 3) 2, NHCONH[C(R 3) 2] n Het 1, OCONH[C(R 3) 2] n N(R 3) 2, OCONH[C(R 3) 2] n Het 1, CO-Het 1, CHO and/or COA, Het denotes a mono- or bicyclic saturated, unsaturated or aromatic heterocycle having 1 to 4 N and/or O and/or S atoms which is unsubstituted or mono- or disubstituted by Hal, A, OR 3, N(R 3) 2, NO 2, CN, COOR 3, CON(R 3) 2, NR 3 COA, NR 3 SO 2 A, COR 3, SO 2 NR 3 and/or S n A, Het' denotes a mono-, bi- or tricyclic saturated, unsaturated or aromatic heterocycle having 1 to 4 N, O and/or S atoms, which is unsubstituted or may be mono- or disubstituted by Hal, A, OR 3, N(R 3) 2, SR 3, NO 2, CN, COOR 3, CON(R 3) 2, NR 3 COA, NR 3 SO 2 A, SO 2 N(R 3) 2, S m A, CO-Het 1, Het 1, [C(R 3)2] n N(R 3)2, [C(R 3) 2] n Het 1, O[C(R 3) 2] n N(R 3) 2, O[C(R 3) 2] n Het 1, NHCOOA, NHCON(R 3) 2, NHCOO[C(R 3) 2] n N(R 3) 2, NHCOO[C(R 3) 2] n Het 1, NHCONH[C(R 3) 2] n N(R 3) 2, NHCONH[C(R 3) 2] n Het 1, OCONH[C(R 3) 2] n N(R 3) 2, OCONH[C(R 3) 2] n Het 1, CO-Het 1, CHO, COA, =S, =NH, =NA and/or =O (carbonyl oxygen), Het 1 denotes a monocyclic saturated heterocycle having 1 to 2 N and/or O atoms, which may be mono- or disubstituted by A, OA, OH, Hal and/or =O (carbonyl oxygen), Hal denotes F, Cl, Br or I, n denotes 0, 1 or 2, m denotes 1 or 2,