Heterocyclic imines and amines. Part 19. Isoquinoline and other products from α,o-dicyanostilbene and basic reagents

Abstract

a,o-Dicyanostilbene (1) was cleaved by hydrazine or hydroxylamine under mildly acid conditions to 0cyanobenzyl cyanide (2) and benzaldehyde, isolated as derivatives. Sodamide with compound (1) gave 1-amino-4-cyano-3-phenylisoquinoline: alkoxides similarly gave the 1 -alkoxy compounds, the presumed intermediate 3,4-dihydroisoquinoline from the methoxide reaction being isolated and separately dehydrogenated. Acid hydrolysis of the 1-ethoxy compound gave the known 4-cyano-3-phenylisoquinolin-1 (2H)-one. With the anion of o-cyanobenzyl cyanide, compound (1) gave a 1-amino-4-cyano-3-(2substituted phenyl)isoquinoline, which was oxidised to 1-amino-4-cyano-3-(2-carboxyphenyl)isoquinoline. The latter lost water at 210 ·C to give yellow 12-cyano-5-iminoisoindolo[2, 1-b]isoquinolin-7 (5H) -one, closely related to known compounds.Many 1,2-and 1,3-dicyano compounds add basic reagents to form heterocyclic products. 2 In continuing studies in this field, we have examined the behaviour of a,o-dicyanostilbene (1) towards hydrazine, hydroxylamine, sodamide, sodium ethoxide, and the anion of o-cyanobenzyl cyanide: isoquinoline products arise. The starting 1,3-dicyanide (1) is readily accessible 3 through Knoevenagel condensation of benzaldehyde with o-cyanobenzyl cyanide (2).

Synthesis and Reactivity of Ortho-Palladated Phenylacetamides. Intramolecular C−N vs C−O Reductive Coupling after CO or XyNC Insertion into the Pd−C Bond. Synthesis of Isoquinoline- and Isocoumarin-Based Heterocycles

“…Moreover, the tmeda complexes 6a − c gradually decomposed when kept in solution under CO at room or higher temperatures (Scheme ). Complete decomposition of 6a was observed after 30 h of reaction of 1a with CO (1.4 bar) at 50 °C in CDCl 3 to give quantitatively colloidal palladium, (tmedaH)I, and isoquinoline-1,3(2 H ,4 H )-dione ( 7a ) (homophthalimide), ,, resulting from the reductive C−N coupling. Decomposition of 6b , formed in situ from 1b under CO, was considerably slower and reached only 71% after 3 days (1.4 bar, 50 °C), giving an approximately 1:2 mixture of 2-methylisoquinoline-1,3(2 H ,4 H )-dione ( 7b ) and the new isocoumarin derivative 3-(methylamino)-1 H -2-benzopyran-1-one ( 8b ), resulting from C−N and C−O couplings, respectively.…”

“…As observed for the previous C−N couplings, the decomposition is much faster for the unsubstituted derivative 1a (30 min at room temperature) than for its methyl-substituted analogue 1b , the latter requiring harsher reaction conditions (3 h at 61 °C). Compounds 11 are new members of the small family of imino derivatives of isoquinoline-1,3(2 H ,4 H )-dione. , The reaction of 1c with 1 equiv of XyNC gave a mixture containing a new organometallic derivative, probably the expected insertion product, and unreacted starting material, which could not be separated. However, heating this mixture at 60 °C for 24 h led to its gradual decomposition to give colloidal Pd, (tmedaH)I, and an almost quantitative yield of the new iminoisocoumarin derivative 1-(2,6-dimethylphenylimino)-3-( N , N -dimethylamino)-1 H -2-benzopyran ( 12c ), resulting from a C−O coupling.…”

Using of 3-Arylisocoumarins in 3-Arylisoquinolons Synthesis

“…Незважаючи на досить жорсткі умови трансформації О-гетероциклу в N-гетероцикл, CN-група при цьому не зазнає будь-яких змін. Цей факт було підтверджено і в більш пізній роботі, автори якої проводили рециклізацію 3-феніл-4-ціаноізокумарину в 3-феніл-4-ціаноізохінолін у концентрованому амоніаці протягом 18 год при 140 °С [8].…”

Synthesis of a Hydrophilic Naphthalimidedioxime

“…After a number of other procedures failed to afford any product in addition to poor step economy, we decided to adjust our strategy. We would not depend upon a lengthy reductive amination sequence to install the hydrophilic carboxylic acid in our new target 14 .…”