There is provided a process for the production a compound of general formula I: ##STR00001## wherein A, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 have meanings given in the description, which process comprises the dehydrogenation of a compound of general formula II, ##STR00002##
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. patent application Ser. No. 09/886,643, filed Jun. 21, 2001, now U.S. Pat. No. 6,730,786, which claims benefit of U.S. Provisional Application No.60/217,794, filed Jul. 12, 2000, and claims benefit of U.S. Provisional Application No. 60/291,126, filed May 16, 2001.
Priority Data
Jun 22, 2000 [GB] 0015462.5 Mar 09, 2001 [GB] 0105873.3
