scheme ii dialkoxybenzo b thiophene may be acylated with the acylating agent described above and the protecting group removed to afford compound iii alternatively as shown in scheme iii subsequent to intramolecular cyclization of acetophenone ii the alkoxy groups of the dialkoxybenzothiophene may be removed to yield a dihydroxybenzothiophene the hydroxy groups may then be reprotected and the resulting protected dihydroxy compound may then be reacted with the acylating agent described above after which the protecting groups are removed the cyclization of a alkoxyphenyl thio 4 alkoxyacetophenone is carried out in polyphosphoric acid ppa with phosphoric acid to yield 6 alkoxy 2 4 alkoxyphenyl benzo b thiophene and 4 alkoxy 2 4 alkoxyphenyl benzo b thiophene the reaction proceeds cleanly without generation of a thick difficult to stir paste according to the invention the cyclization is conducted at temperatures of from about 50 u00b0 to 110 u00b0 c preferably from about 75 u00b0 to 95 u00b0 c and most preferably from about 80 u00b0 to 90 u00b0 c the acetophenone starting material is heated in the ppa h 3 po 4 mixture for at least 30 minutes and preferably from about 60 to 180 minutes as presently practiced the acetophenone is cyclized at about 85 u00b0 c for about 1 75 hours the weight ratio of ppa to h 3 po 4 in this cyclization reaction is from about 10 1 to 1 1 subsequent to this initial heating period the reaction is cooled to a temperature of from about 25.