The compounds of formula (1) wherein R1 represents a phenyl derivative of formulae (a), (b) or (c) R10 is 1-3C-alkyl and R11 is 1-3C-alkyl, or R10 and R11 together with the carbon atom, to which they 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, phenyl substituted by R13, R14, R15 and R16, pyridinyl substituted by R17 and R18, naphthalenyl substituted by R19 and R20, quinolinyl substituted by R21 or indolyl substituted by R22, are novel effective inhibitors of the type 4 phosphodiesterase.
