Abstract: Disclosed are compounds of the formula ##STR1## in which R is hydrogen or alkyl C.sub.1 to C.sub.6 and R.sub.5 and R.sub.10, which may be the same or different, are hydrogen or alkyl C.sub.1 to C.sub.6,X represents a group --AR.sub.6,A is CO or SO.sub.2 and R.sub.6 is halogen, C.sub.1 -C.sub.6 haloalkyl, C.sub.1 -C.sub.6 alkoxy, C.sub.6 -C.sub.9 aryloxy or phenyl optionally substituted by C.sub.1 -C.sub.6 alkyl, and salts, esters, and amides which are intermediates to anti-allergic compounds.

Abstract: There is described a process for the production of a compound of formula I, ##STR1## in which R is hydrogen or alkyl Cl to 6, and R.sub.5 and R.sub.10, which may be the same or different, are each hydrogen or alkyl Cl to 6,or a pharmaceutically acceptable derivative thereof,which comprises removal of an activating group from a compound of formula II, ##STR2## or a suitable derivative thereof, in which R, R.sub.5 and R.sub.10 are as defined above, andX represents an activating group,and if desired or necessary converting the resulting compound of formula I to a pharmaceutically acceptable derivative thereof, or vice versa.There is also described a process for the production of a compound of formula II in which R is hydrogen, or a suitable derivative thereof, which comprises reaction of a compound of formula III, ##STR3## or a suitable derivative thereof, in which R.sub.5 and R.sub.10 are as defined above, with a compound of formula IV,X--N.dbd.C.dbd.O IVin which X is as defined above.