Abstract
Tetrahydro-1,4-benzodiazepin-5-ones with an alkoxy group at the C-6 position were synthesized in 76–82% yields from alkyl haloaryl ethers and 1.3-dimethyl-2-imidazolidinone in the presence of sodium bis(trimethylsilyl)amide at reflux. A bigger alkyl group in haloaryl ethers gave a lower yields of the correspondng benzodiazepinone. The same annellation was also accomplished by use of the t-butyldimethylsilyl haloaryl ether to replace an alkyl haloaryl ether. Nevertheless, partial desilylation took place to lead to the desired benzodiazepinone bearing an –OH group. Although the heterocycle fromation was accomplished by use of 1,3-dimethyl-2-imidazolidinone as the starting materials, its replacement with 3-methyl-2-oxazolidinone, 3-methyl-2-thiazolidinone, or 1-methyl-2-pyrrolidinone did not give the corresponding 7-membered heterocycles. Furthermore, ours results indicate that reaction of meta-iodoanisole with 3-methyl-2-oxazolidinone generated 1-(3-methoxyphenyl)-3-methyl-2-imidazolidinone in 25% yield, of which the structure was confirm by X-ray crystallography. Among various bases including lithium 2,2,6,6-tetramethylpiperidide, sodium bis(trimethylsilyl)amide, sodium tert-butoxide, and sodium hydride, choice of sodium bis(trimethylsilyl)amide was essential for the "one-flask" annellation to proceed.