The compounds of formula (1) wherein R1 represents a phenyl derivative offormulae (a), (b) or (c) R10 is 1-3C-alkyland R11 is 1-3C-alkyl, or R10 and R11 together with the carbon atom, to whichthey are bonded, form a spiro-linked 3-, 4-,5- or 6-membered hydrocarbon ring, A is C(O) or S(O)2, and R12 is phenyl,naphthalenyl, pyridinyl, quinolinyl, isoquinolinyl,quinoxalinyl, 1,6-naphthyridinyl, 1,8-naphthyridinyl, indolyl, phenylsubstituted by R13, R14, R15 and R16, pyridinyl substitutedby R17 and R18, naphthalenyl substituted by R19 and R20, quinolinylsubstituted by R21 or indolyl substituted by R22, are noveleffective inhibitors of the type 4 phosphodiesterase.
