LE>FIGR ID=jo061361ln00001>ls/joceah/71/i20/figures/jo061361ln00001.gif" ALIGN="left" HSPACE=5> |
2-Ary
lsu
lfany
l- and benzy
lsu
lfany
lpyridinium
N-ary
limides (
2), easi
ly avai
lab
le
from tetrazo
lo[1,5-
b]pyridinium sa
lts (
1), participate in 1,3-dipo
lar cyc
loaddition with ary
l isothiocyanates and ary
l isocyanatesto resu
lt in
formation o
f fused thioxo- and oxo[1,2,4]triazo
lium sa
lts (
5 and
12), respective
ly. Thistrans
formation is interpreted as a regu
lar 1,3-cyc
loaddition
fo
llowed by spontaneous e
limination o
f theary
l- or benzy
lsu
lfany
l group. Formation o
f these triazo
lium sa
lts can be
fo
llowed-under appropriatereaction conditions-by ring-opening reactions to a
fford some new triazo
ly
ldienes (
6). Recognition o
fthe intermediate participation o
f the thio
late anion a
long the pathway
1 f">
5 a
llowed e
laboration o
f asimp
le procedure to
5 imp
lying a tandem reaction sequence.