, --S--, or --N(R6), wherein R6 is a hydrogen atom or an optionally substituted alkyl group; R2 is an optionally substituted cycloalkyl...http://www.google.fr/patents/US5723460?utm_source=gb-gplus-shareBrevet US5723460 - Potent and selective phosphodiesterase type iv inhibitors; useful in the prophylaxis and treatment of disease such as asthma where unwanted inflammatory response or muscular spasm