Mi. Burguete et al., N-TOSYLATED POLYAZA[N](1,4)NAPHTHALENOPHANES - SYNTHESIS AND CONFORMATIONAL STUDIES, Journal of organic chemistry, 59(5), 1994, pp. 1067-1071
N-Tosylated polyaza[n](1,4)naphthalenophanes containing from 3 to 6 ni
trogen atoms and from 9 to 18 atoms in the saturated bridge can be pre
pared in high yields from 1,4-bis(bromomethyl)naphthalene and the appr
opriate N-tosylated polyamine chains. NMR data and molecular mechanics
calculations suggest the prevalence of conformations in which the pol
yamine bridge is located above the aromatic ring. Variable-temperature
NMR experiments show that internal rotation of the aromatic ring is n
ot allowed, on the NMR time scale, even at 180 degrees C for naphthale
nophanes having chain lengths of 12 or less. For naphthalenophanes wit
h chain lengths of 14 or 15 atoms, the rotational barrier is on the or
der of 12 kcal mol(-1) as calculated from VT-NMR data.