The present invention provides a process for the preparation of phenylacetic acid compounds 2 where R.sup.2 is an optionally substituted aryl, R.sup.6 is NO.sub.2, NH.sub.2, alkyl, halogen, or a function group readily derived there from and R.sup.4a is hydrogen C.sub.1-6 alkyl, tert-butyl or benzyl The compounds of formula 2a are useful intermediates for the preparation of HIV reverse transcriptase inhibitors ##STR00001##