Alkylation of 2,3-Dihydro-1,4-diazepinium Salts

✍ Scribed by Calsy, Adrianne ;King, James ;Lloyd, Douglas ;Reichardt, Christian ;Struthers, Margot

• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 353 KB
• Volume: 1986
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.198619860809

✦ Synopsis

N-Unsubstituted 2,3-dihydro-1,4-diazepinium salts 4 a -d are N-methylated readily (-5ad) by using iodomethane and potassium carbonate in dimethylformamide. The 2,3dihydro-5,7-diphenyl-I ,4-diazcpinium salt 4 d could be N-ethylated but not N-isopropylated, presumably for steric reasons. Vicinal crowding between 1,4-alkyl and S,7-phenyl substituents at the dihydrodiazepinium ring is evident from NMR spectra. 2,3-Dihydro-6-(hydroxyphcnyl)-l,4-diazepiniuni salts (2a, b) are methylated first at the nitrogen atoms (-1 a, b) and only then at the hydroxy group (-+3a, b). Alkylierung yon 2,3-Dihydro-1,4-diazepinium-Salzen N-Unsubstituiertc 2,3-Dihydro-I ,4-diazepinium-Salze 4a -d werden mit Iodmethan/Kaliumcarbonat in Dimethylformamid leicht N-methyliert (-5a -d). Das 2,3-Dihydro-S,7diphenyl-l,4-diazepinium-Salz 4 d konnte zwar N-ethyliert, aber nicht N-isopropyliert werden, vermutlich aus sterischen Grunden. Sterische Wechselwirkungen zwischen benachbarten 1,4-Alkyl-und 5,7-Phcnylsubstituenten am Dihydrodiazepiniumring lassen sich NMRspektroskopisch nachweiscn. 2,3-Dihydro-6-(hydroxyphenyl)-1,4-diazepinium-Salze (2a, b) werden zunachst an den Stickstoffatomen methyliert (+la, b) und erst danach an dcr Hydroxygruppe (-+3a, b).

When the N,N'-unsubstituted analogues 2a, b were treated with the same reagents it was found that methylation took place first at the two nitrogen atoms