The n.m.r. spectra of S-alkylthiophenium salts, obtained from thiophens with silver tetrafluoroborate and alkyl halides and which are powerful alkylating agents, axe consistent with a pyramidal arrangement for the sulphur-carbon bonds.
A number of derivatives of 2-methyl-3-(o-tolyl)-4(3H)-quinazolone bearing new substituents on the 2-methyl group have been synthesized. It was established that most substitutions at this position reduce or remove the CNS depressant activity of methaqualone. From the series prepared only the 2-fluoromethyl derivative or certain isothiouronium salts, which could be hydrolyzed in vivo to the 2-mercaptomethyl derivative, showed activity of the same magnitude as methaqualone.
Evidence has been obtained that the compound formulated previously as 2-iodobenzimidazole is actually an N-iodo-compound. The preparation of 2-chlorobenzimidazoles by the interaction of phosphoryl chloride and benzimidazolin-2-ones has been systematically studied, and improved yields have been obtained without the use of sealed tubes. The structure of an intermediate isolated from one of these reactions is considered.ALTHOUGH benzimidazolin-2-one (I) is potentially tautomeric, very little of the hydroxyform ( 11) is present in equilibrium under normal conditions.' The known dialkyl and diacyl derivatives are '' fixed " forms derived from structure (I). With the exception of 2-ethoxybenzimidazoleJ2 compounds derived from the hydroxy-form (11) appear not to have been prepared. Two apparent exceptions, the compounds formulated as 2-acetoxy-and 2-acetoxy-l-acetyl-benzimidazole,4 have been shown to be l-acetyl-and 1,3-diacetyl-benzirnidazolin-2-one, respectively. As a possible Toute to compounds derived from the hydroxy-structure might involve nucleophilic displacement of a %halogen substituent, the preparation of 2-halogenobenzimidazoles has been studied.
The synthesis of some quinazolino[3,2‐a][1,4]benzodiazepines from 2‐bromomethyl‐3‐o‐carbomethoxyphenyl‐4(3H)quinazolone is described. Alkylation and acylation of N‐6 led to a series of novel derivatives of this ring system.
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