ISSN:
0170-2041
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Thermal Rearrangements and Nucleophilic Ring cleavage of cis-2,3-Dihydro-2,3-Diphenyl-1H-1,4-diazepinesThermolysis of cis-2,3-dihydro-2,3-diphenyl-1H-1,4-diazepine (c2a) at 150°C in [D5]bromobenzene solution affords quantitatively 2,3-diphenylpyridine (4a) via ring contraction and loss of one mole of ammonia. In striking contrast, on heating a [D5]bromobenzene solution of cis-2,3-dihydro-2,3,6-triphenyl-1H-1,4-diazepine (c2b) to 140°C loss of C7H8 occurs resulting in the formation of 2,5-diphenylpyrimidine (5b) in 70% yield. Mechanisms are proposed in order to rationalize these surprising ring contractions. Piperdine in methanol cleaved the ring of c2a ·H⊕ producing meso-1,2-diphenyl-1,2-ethanediamine (12) and 1,3-dipiperidinopropenylium perchlorate (13).
Notes:
Die Thermolyse von cis-2,3-Dihydro-2,3-diphenyl-1H-1,4-diazepin (c2a) bei 150°C in [D5]Brombenzol ergibt unter Ringkontraktion und Abspaltung von ammoniak quantitativ 2,3-Diphenylpyridin (4a). Dagegen entsteht aus cis-2,3-Dihydro-2,3,6-triphenyl-1H-1,4-diazepin (c2b) bei 140°C in [D5]Brombenzol unter Verlust von C7H8 2,5-Diphenylpyrimidin (5b) in 70% Ausbeute. Für diese überraschenden Ringkontraktionen werden Mechanismen vorgeschlagen. Durch Piperidin in Methanol wird c2a ·H⊕ in meso-1,2-Diphenyl-1,2-ethandiamin (12) und 1,3-Dipiperidinopropenylium-perchlorat (13) gespalten.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.198319830715
