Process for preparing pyrrolidinones

A process for the preparation of a compound of formula II:

• ##STR20## 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 with halogen, hydroxy, SO.sub.2 NR.sup.a R.sup.b where R.sup.a and R.sup.b are independently H or C.sub.1 -C.sub.6 alkyl, SiR.sub.3.sup.c where each R.sup.c is independently C.sub.1 -C.sub.4 alkyl or phenyl, cyano, nitro, amino, mono- and dialkylamino, acylamino, C.sub.1 -C.sub.6 alkoxy, C.sub.1 -C.sub.6 haloalkoxy, C.sub.1 -C.sub.6 alkylthio, C.sub.1 -C.sub.6 alkylsulphinyl, C.sub.1 -C.sub.6 alkylsulphonyl, carboxy, carboxyamide in which the groups attached to the N atom may be hydrogen or optionally substituted lower hydrocarbyl, alkoxy carbonyl, or aryl;
• 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 aromatic or heteroaromatic ring system optionally substituted with one or more substituents selected from:
• halogen, C.sub.1 -C.sub.10 hydrocarbyl, --O(C.sub.1 -C.sub.10 hydrocarbyl), --S(C.sub.1 -C.sub.10 hydrocarbyl), --SO(C.sub.1 -C.sub.10 hydrocarbyl) or --SO.sub.2 (C.sub.1 -C.sub.10 hydrocarbyl), cyano, nitro, SCN, SiR.sub.3.sup.c, COR.sup.7, CR.sup.7 NOR.sup.8, NHOH, ONR.sup.7 R.sup.8, SF.sub.5, COOR.sup.7, SO.sub.2 NR.sup.7 R.sup.8, OR.sup.9 and NR.sup.10 R.sup.11 ;
• and in which any ring nitrogen atom may be quaternised or oxidised;
• or any two substituents of the group A may combine to form a fused 5- or 6-membered saturated or partially saturated carbocyclic or heterocyclic ring in which any carbon or quaternised nitrogen atom may be substituted with any of the substituents mentioned above for A or in which a ring carbon atom may be oxidised;
• R.sup.7 and R.sup.8 are each independently hydrogen or C.sub.1 -C.sub.10 hydrocarbyl;
• R.sup.9 is hydrogen, C.sub.1 -C.sub.10 hydrocarbyl, SO.sub.2 (C.sub.1 -C.sub.10 hydrocarbyl), CHO, CO(C.sub.1 -C.sub.10 hydrocarbyl), COO(C.sub.1 -C.sub.10 hydrocarbyl) or CONR.sup.7 R.sup.8 ;
• R.sup.10 and R.sup.11 are each independently hydrogen, C.sub.1 -C.sub.10 hydrocarbyl, O(C.sub.1 -C.sub.10 hydrocarbyl), SO.sub.2 (C.sub.1 -C.sub.10 hydrocarbyl), CHO, CO(C.sub.1 -C.sub.10 hydrocarbyl), COO(C.sub.1 -C.sub.10 hydrocarbyl) or CONR.sup.7 R.sup.8 ;
• any of the hydrocarbyl groups within the group A may optionally be substituted with halogen, hydroxy, SO.sub.2 NR.sup.a R.sup.b, cyano, nitro, amino, mono- or dialkylamino, acylamino, C.sub.1 -C.sub.6 alkoxy, C.sub.1 -C.sub.6 haloalkoxy, C.sub.1 -C.sub.6 alkylthio, C.sub.1 -C.sub.6 alkylsulphinyl, C.sub.1 -C.sub.6 alkylsulphonyl, carboxy, carboxyamide in which the groups attached to the N atom may be hydrogen or lower hydrocarbyl optionally substituted with halogen, alkoxy carbonyl, or aryl;
• R.sup.21 is hydrogen, halogen, OH, or OCONHR.sup.1, wherein R.sup.1 is as defined above;
• the process comprising cyclising a compound of formula III:
• ##STR21## wherein A, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.21 are as defined in formula II and R.sup.25 is a leaving group;
• under basic conditions.