1-Isoquinolone from isoquinoline

If quinoline derivatives are expected to be synthesized by this procedure, the starting cycloalkene should contain a cyclobutene ring. When cyclobutene derivative 65c is reacted with Ig under ethylene gas, isoquinoline derivative 66c is obtained in 60% yield. Furthermore, cyclic amino acid ester 66d is obtained from glycine derivative 65d in 75% yield by a one-step reaction. Various isoquinolone derivatives 66e-66i are also synthesized from cyclobutenyl amides... 

Similarly, application to the chemistry of isoquinoline alkaloids allowed the preparation of a 1-isoquinolone derivative in good yield from the corresponding enamine30 (Scheme 16). 

Simple isoquinolines are not found in the Menispermaceae of South America. The isoquinolone thalifoline (1) was identified from Abuta pahni [32], Benzyltetrahydroisoquinolines are the biogenetic precursors for aporphines, proaporphines, and oxoaporphines. Yet the only such compound isolated from South American Menispermaceae is (+) coclaurine (2) obtained from Sciadotema eichleriam [52] and Caryomene olivascens [37-38]. The chemistry of simple isoquinolines [65], isoquinolones [66], and benzyltetrahydroisoquinolines [67] have been reviewed. 

Homophthalic acid surprisingly yields an isoquinoline upon Vilsmeier formylation, apparently by rearrangement and cyclization of the side-chain formylated intermediate (Scheme 25). This intermediate may be isolated at low temperatures.64 In a related manner the isoquinolone (87) has been synthesized from the toluic acid (86).64a... 

Various isoquinolines and isoquinoline alkaloids are easily available from isoquinolones... 

The occurrence of isoquinoline alkaloids in the genus Aristolochia is limited to three species, A. arcuata, A. elegans and A. gehrtii. Isolates of this calss were listed in the Table 13. Most of these alkaloids reported from Aristolochia were tetrahydroisoquinoline type, except 168 which is fully aromatic. It is interesting to note that all the alkaloids isolated from A. arcuata [285] were isoquinolines whereas all the alkaloids from A. elegans were isoquinolones with a carbonyl function at C-l. The... 

Isoquinoline is derived from naphthalene by replacement of a p-CH group by nitrogen. The isoquinolinium ion and 1-isoquinolone [isoquinolin-l(2//)-one, isocarbostyril] are important... 

As for quinolines, isoquinoline derivatives can be prepared by ring transformation of other heterocycles. For instance, oxazole-4-carboxylic ester 74, obtained from phthalic anhydride and isocyanoacetic ester, is converted into the l-isoquinolone-3-carboxylic ester 75 in an acidic medium, probably by hydrolysis to the enaminocarboxylic acid 76 followed by cyclization. 

The 4-(methoxycarbonylamino)isoquinolone (163) is prepared in 84% yield by cyclization of compound (162) with methanesulphonic acid. The starting material is obtained from benzylamine, glyoxylic acid (HCOCO2H), and methyl carbamate (H2NC02Me) (Scheme 66).Aluminium-chloride-promoted cyclization of the benzylaminopropyl bromide (164) gives 64% of the isoquinoline (165) and 14% of the benzazepine (166) (Scheme 67). ... 

Hostalkova A, Novak Z, Pour M, Jirosova A, Opletal L, Kunes J, et al. Berfaanine A new isoquinoline-isoquinolone alkaloid from Berberis vulgaris (Berberidaceae). Nat Prod Commun 2013 8(4) 441-2. 

Aromatic isoquinolones can be obtained by the thermal rearrangement of isoquinoline iV-oxides thus it was possible to derive the isoquinoline 3 from the iV-oxide 2. Compound 3 could be further functionalized through bromina-tion and subsequent treatment with a mixture of cuprous cyanide and sodium cyanide. ... 

Isoquinolines (and isoquinolones ) can also be prepared from cyclopalla-dated imines (Scheme 36). The reactions look very promising in that a variety... 

From the benzylisoquinolines are derived all the types of isoquinoline alkaloids found in the Annonaceae (Fig. 3) berberines, aporphines, oxoaporphines, phenanthrenes, cularines, morphinanedienones, isoquinolones, dimethylaminoethyl-benziles and bisbenzylisoquinolines. 

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