An Efficient Procedure for the Preparation of 3′-Acetyl-2′,3′-dihydrobenzothiazoles by Ring Contraction of 2′,3′-Dihydro-1,5-Benzothiazepines Under Acetylating Conditions
摘要:
Reaction of 2-benzoyl-6-hydroxy-3-methyl-5-(2'-substituted-2',3'-dihydro-1,5-benzothiazepin-4'-yl) benzofurans (4a-f) with a mixture of acetic anhydride and pyridine afforded 6-acetoxy-2-benzoyl-3-methyl-5-(3'-acetyl-2'-substitutedstyryl-2',3'-dihydrobenzothiazole-2'-yl) benzofurans (5a-f) as sole products in good yields. A reaction mechanism for the ring contraction is proposed. All the compounds (5a-f) were screened for their antifeedant activity by the "Non-Choice test method" using 6 h prestarved fourth instar larvae of Spodoptera litura F. Compounds 5a, 5c and 5d exhibited highest antifeedant activity.
An Efficient Procedure for the Preparation of 3′-Acetyl-2′,3′-dihydrobenzothiazoles by Ring Contraction of 2′,3′-Dihydro-1,5-Benzothiazepines Under Acetylating Conditions
摘要:
Reaction of 2-benzoyl-6-hydroxy-3-methyl-5-(2'-substituted-2',3'-dihydro-1,5-benzothiazepin-4'-yl) benzofurans (4a-f) with a mixture of acetic anhydride and pyridine afforded 6-acetoxy-2-benzoyl-3-methyl-5-(3'-acetyl-2'-substitutedstyryl-2',3'-dihydrobenzothiazole-2'-yl) benzofurans (5a-f) as sole products in good yields. A reaction mechanism for the ring contraction is proposed. All the compounds (5a-f) were screened for their antifeedant activity by the "Non-Choice test method" using 6 h prestarved fourth instar larvae of Spodoptera litura F. Compounds 5a, 5c and 5d exhibited highest antifeedant activity.