The acylation of 1,4-dimethylcarbazole, 1, by an acid chloride or acetic anhydride according to the Friedel-Crafts reaction led to diacylcarbazoles 4, 6, 8, 10, 11 or to monoacylcarbazoles 5, 7, 9, 12, 13 and 14. The 3-acetyl-6-methoxy 6-nitrocarbazoles could be obtained by the same route. The 6-methoxycarbazole 3 afforded directly the 3-acyl-6-hydroxycarbazoles 15 and 16. The 3-nitro-1,4-dimethyl-9H-carbazoles 17a, 18, 19, 20, 24 and 25 could be obtained by nitration of 3,6-acyl-dimethylcarbazoles or 6-acyl-1,4-dimethylcarbazoles. The 3-aminocarbazoles 26, 30, 32 and 34 were provided by the reduction of the corresponding nitro derivatives with stannous chloride. The action of sodium borohydride in excess on the 3-nitrocarbazole 17 led directly to the 3-amino-6-hydroxy-3-nitrocarbazole 31. The 6-acyl-3-nitrocarbazoles afford the hydrazones 38 and 41 after reaction with hydrazine. Their reduction with sodium borohydride led to the secondary alcohols 35 and 37, while the Schmidt rearrangement allowed the access to the acetamides 42 and 44.
Efficient Synthesis of 6-substituted 3-nitro-1,4-dimethylcarbazoles and 3-amino-1,4-dimethylcarbazoles
SATURNINO, Carmela;
1991-01-01
Abstract
The acylation of 1,4-dimethylcarbazole, 1, by an acid chloride or acetic anhydride according to the Friedel-Crafts reaction led to diacylcarbazoles 4, 6, 8, 10, 11 or to monoacylcarbazoles 5, 7, 9, 12, 13 and 14. The 3-acetyl-6-methoxy 6-nitrocarbazoles could be obtained by the same route. The 6-methoxycarbazole 3 afforded directly the 3-acyl-6-hydroxycarbazoles 15 and 16. The 3-nitro-1,4-dimethyl-9H-carbazoles 17a, 18, 19, 20, 24 and 25 could be obtained by nitration of 3,6-acyl-dimethylcarbazoles or 6-acyl-1,4-dimethylcarbazoles. The 3-aminocarbazoles 26, 30, 32 and 34 were provided by the reduction of the corresponding nitro derivatives with stannous chloride. The action of sodium borohydride in excess on the 3-nitrocarbazole 17 led directly to the 3-amino-6-hydroxy-3-nitrocarbazole 31. The 6-acyl-3-nitrocarbazoles afford the hydrazones 38 and 41 after reaction with hydrazine. Their reduction with sodium borohydride led to the secondary alcohols 35 and 37, while the Schmidt rearrangement allowed the access to the acetamides 42 and 44.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
