New compounds of the formula (VIIIa) are disclosed ##STR1## wherein R.sup.1 is hydrogen, methyl or ethyl;R.sup.2 is hydrogen, fluoro, or alkyl having 1 to 4 carbon atoms;R.sup.3 is hydrogen, phenyl, alkoxy having 1 to 6 carbon atoms; phenoxy, thenoyl, or benzoyl; orR.sup.2 and R.sup.3 together with the phenyl group to which they are attached form a naphthyl group which is unsubstituted or substituted by C.sub.1 to C.sub.4 alkyl or C.sub.1 to C.sub.4 alkoxy;R.sup.10 is phenylaminocarbonyl, 1-phenyl-5-tetrazolyl, a group --SO.sub.2 OMe, wherein Me is a metal atom selected from the group which consists of sodium or potassium, or a group --SO.sub.2 R.sup.6 in which R.sup.6 is alkyl having 1 to 4 carbon atoms, 4-methylphenyl, amino, C.sub.1 to C.sub.4 alkoxycarbonyl-amino, or benzoylamino, or R.sup.10 is a group ##STR2## in which R.sup.7 is cycloalkyl having 5 to 6 carbon atoms, and R is vinyl. The compounds are intermediates useful in the preparation of arylacetic acids having antiinflammatory compounds.