Abstract
Fused nitrogen-containing heterocycles with seven or more atoms form the structural scaffold of many natural and synthetic molecules possessing diverse range of biological activity. A series of new fused azepanes and azonanes have been prepared
via
two sequential Hofmann-type cleavages of the endocyclic C–N bonds in azetidinium rings of decahydro-1
H
,6
H
-biscyclopenta[2,3]azeto[1,2-a:2’1’-e]pyrrolium system. The latter resulted from double intramolecular alkylation of pyrrolidine nitrogen in (1
R
(
S
),5
R
(
S
),7
R
(
S
),8
R
(
S
))-6-azadispiro[4.1.4.2]tridecane-1,8-diyldimethanol (
7
), which easily occurs under Appel reaction conditions. A simple 7-step synthesis of
7
from 1-chloronon-8-en-4-one and unsubstituted hydroxylamine
via
intramolecular 1,3-dipolar cycloaddition in α-pent-4-en-1-yl nitrones of pyrroline series was described earlier.