Process for preparation 4,5,6,7-tetrahydro-7-oxobenzo-[b]-thiophenes and 1,2,3,4-tetrahydro-4-oxo-1-naphthalenes

DETAILED DESCRIPTION I claim: 1.
A process for the preparation of a compound of the formula: ##STR13## wherein R.
sub.
1 and R.
sub.
2 are each a substituent selected from the group consisting of alkanoyl C.
sub.
1 -C.
sub.
7, halogen-substituted ##STR14## R.
sub.
3 is a substituent from hydrogen and alkyl C.
sub.
1 -C.
sub.
4 ; R.
sub.
4 is a substituent selected from hydrogen, alkyl C.
sub.
1 -C.
sub.
8, alkanoyl C.
sub.
1 -C.
sub.
4, halogen-substituted alkanoyl C.
sub.
2 -C.
sub.
4 and ##STR15## and when ##STR16## is each cyclized, each represents phthalimido; X and Y are selected from hydrogen, halogen, nitro, alkyl C.
sub.
1 -C.
sub.
4 and alkoxy C.
sub.
1 -C.
sub.
4 ; the racemic mixtures and the optical isomers thereof, consisting essentially in the steps of: oxidizing a compound of the formula: ##STR17## wherein R.
sub.
1 and R.
sub.
2 are each a substituent as hereinabove defined; with 2.
5 to 3.
2 molar equivalents of potassium permanganate at a temperature ranging from 0.
degree.
C.
to 50.
degree.
C.
, in a solvent selected from aqueous solutions of acetone, tert-butanol, pyridine and acetonitrile, in the pH of from 6 to below 11, in the presence of a buffer selected from magnesium sulfate, calcium sulfate, sodium bicarbonate and acetic acid, for a period of time sufficient to essentially complete the reaction and recovering a compound of the formula: ##STR18## where R.
sub.
1 and R.
sub.
2 are as defined hereinabove.
2.
The process according to claim 1, wherein R.
sub.
1 and R.
sub.
2 each are selected from alkanoyl C-hd 1-C.
sub.
2, and ##STR19## R.
sub.
3 and R.
sub.
4 each are hydrogen; the compounds are oxidized with 2.
5 to 3.
2 molar equivalents of potassium permanganate at a temperature ranging from 10.
degree.
C.
to 20.
degree.
C.
, in a solvent selected from aqueous solutions of acetone, tert-butanol and pyridine, in the pH range of 7 to 9, in the presence of a buffer selected from magnesium sulfate, calcium sulfate, sodium bicarbonate and acetic acid; for a period of time of from three to sixteen hours.
3.
The process according to claim 1, wherein the compound to be oxidized is N-(4,5,6,7-tetrahydrobenzo[b]thien-4-yl)formamide