Abstract
o-Cyanobenzyl cyanide does not form an imidate with methoxide but undergoes dimeric addition end cyclization to 1-amino-4-cyano-3-(o-cyanobengyl)isocruinoline. A better yield of this product is obtained from the action of sodamide in formamide on the dinitrile but with this reagent a secondary reaction occurs by attack of the formamido anion, generated in the reaction, on the dinitrile, to afford a mixture of cis-and trans-l-amino-3-formamidoisoquinoline. o-a-Dicyanostilbene, from the piperidine catalysed condensation of o-cyanobenzyl cyanide with benzaldehyde, suffers nucleophilic addition across the aryl nitrile group on treatment with sodamide in formamide to yield l-amino-4-cyano-3-phenylisoquinoline. Analogous 1-alkoxy isoquinolines are obtained by reacting the stilbene with catalytic amounts of alkoxides in the corresponding alcohols but, in the reactions examined, the yield decreases with increasing basicity of the alkoxide. The 3,4-dihydroisoquinoline is an intermediate which can be isolated by rigorously excluding oxygen from the system. Hydrazine does not add across the nitrile groups of o-a-dicyanostilbene but effects cleavage of the olefinic group to yield o-cyanobenzyl cyanide and benzaldehyde. Hydroxylamine, on the other hand, forms the acyclic bis-amidoxime which, whilst stable in base, suffers cleavage of the ethylenic group in mild acid and cyclises to homophthal-imide dioxime. Nucleophilio addition of o-cyanobenzyl cyanide to o-a-dicyanostilbene is achieved in the presence of methoxide, the product being a substituted isoquinoline. Reexamination of the reaction between o-cyanobenzyl cyanide and benzaldehyde in the presence of methoxide has led to determination of the structure of the major product, an adduct of two molecules of the dinitrile and one of the aldehyde.