Zeneca Limited

Kevin James Gillen

John M Cox

Ian R Matthews

Stephen Christopher Smith

Russell Martin Ellis

Shaheen Khatoon Vohra

A process for the preparation of a compound of general formula II: ##STR1## wherein R.sup.1 is hydrogen, or C.sub.1 -C.sub.10 hydrocarbyl or heterocyclyl having 3 to 8 ring atoms, either of which may optionally be substituted; each R.sup.2, R.sup.3, R.sup.4 and R.sup.5 is independently hydrogen or C.sub.1 -C.sub.4 alkyl; A is an optionally substituted aromatic or heteroaromatic ring system; and R.sup.21 is hydrogen, halogen, OH or OCONHR.sup.1, wherein R.sup.1 is as defined above; the process comprising cyclizing a compound of general formula III: ##STR2## wherein A, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.21 are as defined in general formula II and R.sup.25 is a leaving group such as a halogen atom; under basic conditions.

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Maidenhead, United Kingdom

Kevin James Gillen