Vj. Aran et al., APPROACHES TO 1,1-DISUBSTITUTED CINNOLIN-3-YLIO OXIDES - SYNTHESIS AND REACTIVITY OF A NEW CLASS OF HETEROCYCLIC BETAINES, Journal of the Chemical Society. Perkin transactions. I, (15), 1997, pp. 2229-2235
The cinnolin-3-ylio oxides 6, a new class of heterocyclic aminimide, c
an be prepared by intramolecular cyclization of the N',N'-disubstitute
d (2-fluorophenyl)acetohydrazides 5. Attempts to prepare these betaine
s by an alternative route, namely cyclization of the nitrenes expected
from the thermal decomposition of (2-dialkylaminophenyl)acetyl azides
11, failed, Curtius rearrangement-derived compounds being the main pr
oducts isolated from these processes, Hydrochlorides of the cinnolin-3
-ylio oxides 6 undergo alkyl halide elimination to yield the 1-(omega-
chloroalkyl)cinnolin-3-ols 19a,b or 1-methylcinnolin-3-ol 21. Oxidatio
n of the latter to the 3-hydroxycinnolin-4-one 22, its methylation to
the corresponding N-1,O- 23 and N-1,N-2-dimethyl 24 derivatives as wel
l as the cyclization of 1-(5-chloropentyl)cinnolin-3-ol 19a to the dia
zepino[1,2-a]cinnolinone 20 are also reported.