Synthetic Studies on Nitrogen Heterocycles

[摘要] Part 1 Treatment of the chlorohydrin (49), of the Reissert compound, 2-acetyl-l-cyano-1,2-dihydroisoquinoline (48) with sodium ethoxide gives 1-ethoxy-3-methylisoquinoline-4-carbaldehyde (50) and highly coloured by-products. A deep purple compound has been isolated from the reaction mixture, and identified as ethyl 2-amino-1-oxo-inden-3-carboxylate (51). This first example of a simple 2-amino-indenone has been synthesised from ethyl homophthalate. Attempts were made to find an alternative synthetic route using indanone and 2-methyl-2-nitrosopropane. Several chlorohydrin alkyl ethers, 2-benzoyl-4-chloro-1-cyano-3-ethoxy-1,2,3,4-tetrahydroisoquinoline (27), and the corresponding 3-methoxy compound (28) were prepared from Reissert compound, 2-benzoyl-1-cyano-1,2-dihydroisoquinoline (2). The stereochemistry of these ethers was investigated. With triethylamine there was a 1,4-elimination of hydrogen chloride to give reactive intermediates (29) and (30), respectively, which were trapped as Diels-Alder adducts (83) and (84) with N-phenylmaleimide. The stereochemistry of these adducts was determined using 1H n. m. r. nuclear Overhauser enhancement spectra. Other Reissert compounds and their derivatives have been studied briefly. Part 2 Oxidation of benzyl N-hydroxycarbamate, PhCH2OCONHOH (55a), with sodium periodate in the presence of cyclopentadiene gave the cycloadduct (87a) of the transient dienophile, benzyl C-nitrosoformate, PhCH2OCONO (56a), and the diene. The cycloadduct (87b) of tert-butyl C-nitrosoformate, ButOCONO (56b) was prepared similarly. Both cycloadducts dissociated reversibly in benzene at 80

[发布机构] University:University of Glasgow

[关键词] Organic chemistry