Masanobu Tani

Fischer indolization of 2-sulfonyloxyphenylhydrazones: A new and practical approach for preparing 7-oxygenated indoles and application to the first synthesis of eudistomidin-A. (Fischer indolization and its related compounds. Part 28)☆☆☆

Abstract An efficient method for synthesis of 7-oxygenated indoles was established by Fischer indolization of the phenylhydrazones ( 10 ) with a sulfonyloxy group at the ortho -position. This method was applied to the first synthesis of the calmodulin antagonist eudistomidin-A ( 2 ).

Regioselective bromination of methoxy derivatives of ethyl indole-2-carboxylate [synthetic studies of indoles and related compounds. XXX]

Bromination of ethyl methoxyindole-2-carboxylates (1) with bromine in acetic acid proceeded on the benzene moiety of 1, whereas the reaction of 1 with pyridinium bromide perbromide in pyridine or N-bromosuccinimide in dimethylformamide gave ethyl 3-bromo-methoxyindole-2-carboxylates (2)

Heterocyclic systems containing bridgehead nitrogen atoms. Part LXVIII. Reaction of 5-fluorobenzimidazolyl-2-thione with chloroacetic acid: studies of orientation of cyclization in the syntheses of 6-fluoro- and 7-fluorothiazolo[3,2-a]benzimidazol-3(2-H)-ones

Abstract 4-Fluoroaniline on successive acetylation, nitration and hydrolysis affords 4-fluoro-2-nitroaniline which on reduction with Raney nickel and hydrazine hydrate followed by treatment of the resulting diamine with carbon disulphide in situ gives 5-fluorobenzimidazolyl-2-thione. The thione on condensation with chloroacetic acid yields [(5-fluoro-2-benzimidazolyl)-thioe]acetic acid which on cyclization in a mixture of acetic anhydride and pyridine furnishes two isomers viz . 6-fluoro- and 7-fluorothiazolo[3,2- a ]benzimidazol-3(2 H )-ones. The condensation of thione with 1,2-dibromoethane affords sym -bis-(5-fluorobenzimidazo-2-yl-mercapto)ethane. The structural assignments for the 6-fluoro- and 7-fluorothiazolo[3,2- a ]benzimidazol-3(2 H )-ones have been made by 1H NMR spectral data using two different methods.

The vilsmeier-haack reaction on methyl homologues of N-benzyltetrahydrocarbazole (synthetic studies on indoles 52')

To examine the steric effect in the Vilsmeier-Haack reaction of N-benzyl-1,2,3,4-tetrahydrocarbazole (1), the reactions were carried out on three methyl homologues of 1. It was found that 1-methyl- or 4,4-dimethyl group has a large effect on reactivity due to their steric bulkiness. This result shows the importance of an initial attack at the 4a-position for the formation of these products.