チオフェノールとジケテンとの反応および4-メチル-2 H-1ベンゾチオピラン-2-オン誘導体のケイ光性

The reaction of thiophenol with diketene in the presence of small amounts of concentrated sulfuric acid offers a convenient method for the synthesis of acetacetylthiophenylester. An equimolar quantity of 100%--sulfuric acid was the. rp-ost u-eff- ective. cat. alys. t for the. r. e. actl on i, n, The synthesis of acetacetylthiophenyl- etrm at temperatures in the range from Oe to about 300ester was urfsuccessful by using 70%e-sulfuric acid, 70%-perchloric acid, concentrated hydrochloric acid, p-toluenesulfonic acid or triethylamine as a catalyst, or eyen arger amo. un. ts of c. on. ceptrated sulfUfic acid. Apph cation of this reaction to substituted thiophenols and thienapht. hols gave th6 corresponding-Acetacetylthioarylesters. On the basis of these obseryations, a mechanislin. of th e reactihon wds discussed.4-Methyl-2 H-1-benzothiopyran-2-ons have been prepared by 6Y610dehydration of acetacetylthioarylesters by the treatment. with. polyphos orig acid. The A oresceVnce of 4-methyl-2 H-benzethiopyran-2-ons was weaker in ethanol and stronger in perchloric acid than those of 4-methylcoumarins and 4-methylcarbostyrils.