A synthesis of 3-phenyl-1,2,3,4-tetrahydroisoquinoline and 2-phenyl-1,2,4,5-tetrahydro-3H-3-benzazepine via Pummerer-type cyclization: enhancing effect of boron trifluoride diethyl etherate on the cyclization.
Chem Pharm Bull (Tokyo)
; 49(8): 979-84, 2001 Aug.
Article
em En
| MEDLINE
| ID: mdl-11515589
ABSTRACT
A synthesis of 6,7-dimethoxy-3-phenyl-1,2,3,4-tetrahydroisoquinoline (14a) and 7,8-dimethoxy-2-phenyl-1,2,4,5-tetrahydro-3H-3-benzazepine (14b) was achieved via the cyclization of N-(3,4-dimethoxyphenyl)methyl-1-phenyl-2-(phenylsulfinyl)ethylformamide (6a) and N-2-(3,4-dimethoxyphenyl)ethyl-1-phenyl-2-(phenylsulfinyl)-ethylformamide (6b) using the Pummerer reaction as a key step, respectively. The Pummerer reaction of 6a,b under usual conditions using trifluoroacetic anhydride yielded the vinyl sulfides (8a, b), non-cyclized products, as a major product. The cyclization proceeded when boron trifluoride diethyl etherate was used as an additive reagent, thus giving rise to the corresponding cyclized products (7a) and (7b) in moderate yields. We propose that the enhancing effect of the Lewis acid on the cyclization may be attributable to the involvement of a dicationic intermediate, sulfonium-carbenium dication (23).
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Benzazepinas
/
Boranos
/
Isoquinolinas
Idioma:
En
Revista:
Chem Pharm Bull (Tokyo)
Ano de publicação:
2001
Tipo de documento:
Article