Isoquinolinium perchlorate

Nitropyrido[l,2-A]quinolin-6-ium-l 1-olate (6%) was isolated from a reaction mixture obtained by photoirradiation of crystalline photochromic 2-(2, 4 -dinitrobenzyl)pyridine for 10 days <2004JP0865>. Reaction of l-(3-chloropropyl)-6,7-dimethoxy-3-methylbenzo[c]pyrylium perchlorate with hydrazines and hydroxylamine in refluxing MeOH afforded 9,10-dimethoxy-6-methyl-, -4,6-dimethyl-l,2,3,4-tetrahydropyridazino[6,l-tf]isoquinoli-nium, and 9,10-dimethoxy-6-methyl-l,2,3,4-tetrahydro[l,2]oxazino[3,2- ]isoquinolinium, perchlorates, respectively <2004CHE1131>. 

Condensation of 2-methyl-4-phenylpyrimido[2,l-a]isoquinolinium perchlorate (173) with p-dimethylaminobenzaldehyde in acetic acid at 120-125°C for 10 min gave 2-(p-dimethylaminostyryl) derivative 174 (74KGS1148). Reaction of 1 lb-methyl-1,3,4,6,7,1 lb-hexahydro-2/f-pyrimido[2,l-a]isoquinolin-2-one (111) with aromatic aldehydes in acetic acid in the presence of acetic anhydride at 100°C for 4-5 h afforded lib-sty ryl derivatives (175) (93KGS499). 

Pyrimido[2,l -a]isoquinolinium perchlorates (316) were obtained in the reactions of 1-aminoisoquinoline and /3-diketones in acetic acid at 260°C for 2 h in sealed tubes and with phenyl and methyl 2-chlorovinyl ketones in acetic acid at 100°C for 5-10 min, then treatment with perchloric acid (74KGS1148). 

H-[l,3]oxazino[3,2-b]isoquinolinium perchlorate gave 2-(3-hydroxy-propyl)perhydroisoquinol-3-one under basic conditions (75CJC2791). Both perchlorates were stable under acidic conditions (75CJC2791, 75CJC3029). 

Phenyl-2,3,4,6,7,l 16-hexahydro[l,3]thiazino[2,3-a]isoquinoline was obtained by the reduction of 4-phenyl-2//-[l,3]thiazino[2,3-a]isoquinolinium perchlorate and its 3,4-dihydro derivatives with KBH4 in methanol (74IJC1242). Reduction of 4-methyl-5,6-dihydro-2//-[l,3]thiazino[2,3-ajisoquinolinium perchlorate with either NaBH4 or sodium cyanoborohy-dride gave a mixture of 4-methyl-2,3,4,6,7,116-hexahydro[l,3]thiazino[2,3-a]isoquinoline and 1,2,3,4-tetrahydroisoquinoline [81IJC(B)372]. 

The reduction of 3-methylthiazolo[2,3-a]isoquinolinium perchlorate (466) and its 2,3-dihydro derivative (467) led to the same three products with both NBH and LAH. The formation of469 was favored with borohydride, whereas 468 and 470 were the major product with LAH. Reductive ring cleavage of thiazoles is known and has been reported previously. ... 

This annelation reaction has been extended to mesityl oxide and related ketones. Thus (6), isoquinolinium perchlorate, reacts with mesityl oxide at 120° (several hours) to form (7) by a spontaneous oxidative aromatization. 

Treatment of benzopyrilium perchlorates (159) with excess hydrazine hydrate in refluxing EtOH has provided 5/f-benzo-2,3-diazepines (160) in 63-75% yield (Scheme 23) <93KGS1475>. Reaction of (159 R = Me, R = C02Et, CN) with one equivalent of hydrazine hydrate aflbrds 2-amino-isoquinolinium perchlorates (161) in 90% yield, which, in the case of the 4-cyano compound, proceeds to the benzodiazepine (160 R = Me, R = CN) in 73% yield. 

Isoquinolinium perchlorate heated several hrs. at 120° with mesityl oxide >- product. Y 35%. F. e. s. D. D. Chapman, Chem. Commun. 1975, 489. 

---