A method for the preparation of a compound of formula IV
wherein W is CN, NO 2 , COOR 1 or COR 2 ;
R 1 and R 2 are each independently C 1 -C 4 alkyl;
R' is hydrogen or R;
R is C 1 -C 6 alkyl optionally substituted with one C 1 -C 4 alkoxy or phenyl group;
n is an integer of 1, 2 , 3, 4, 5, 6, 7 or 8;
A is


L is hydrogen or halogen;
M and Q are each independently hydrogen, halogen, CN, NO 2 , C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 1 -C 4 alkoxy, C 1 -C 4 haloalkoxy, C 1 -C 4 alkylthio, C 1 -C 4 alkylsulfinyl or when M and Q are on adjacent positions they may be taken together with the carbon atoms to which they are attached to form a ring in which MQ represents the structure

        -OCH 2 O-, -OCF 2 O- or -CH=CH-CH=CH-;


R 1 and R 2 are each independently C 1 -C 4 alkyl;
R 3 , R 4 and R 5 are each independently hydrogen, halogen, NO 2 , CHO or R 4 and R 5 may be taken together with the atoms to which they are attached to form a ring in which R 4 R 5 is represented by the structure

R 6 , R 7 , R 8 and R 9 are each independently hydrogen, halogen, CN or NO 2 ; and
X is O or S
which comprises reacting an intermediate compound of formula I or formula II wherein n, A and R are as
described hereinabove for formula IV and q is an integer of 1, 2, or 3 and Anion -q is a proton acceptor having a negative q charge with at least q molar equivalents of a dieneophile of formula V
wherein W is as described hereinabove for formula (IV) and Y is hydrogen, Cl or Br with the proviso that when said intermediate compound is formula I then Y must be Cl or Br, in the presence of a solvent and essentially in the absence of water.
There are also provided ammonium oxazole intermediates of formula I and amino oxazolium intermediates of formula II, useful in the manufacture of insecticidal arylpyrrole compounds.