In order to establish a comparative analysis of chemical shifts caused by r
ing compression effects or by the presence of a chlorine atom on strained c
hlorinated carbons, a series of the chlorinated and dechlorinated polycycli
c structures derived from "aldrin" (5) and "isodrin" (14) was studied. Comp
ounds were classified in four different groups, according to their conforma
tion and number of ring such as: endo-exo and endo-endo tetracyclics, penta
cyclics and hexacyclics. The C-13 chemical shift comparison between the chl
orinated and dechlorinated compounds showed that when C-9 and C-10 are olef
inic carbons, it occurs a shielding of 0.5-2.4 ppm for endo-endo tetracycli
cs and of 4.7-7.6 ppm for endo-exo tetracyclic. The chemical shift variatio
n for C-11 reaches 49-53 ppm for endo-exo and endo-endo tetracyclics, 54 pp
m for pentacyclic and 56-59 ppm for hexacyclic compounds. From these data,
it was possible to observe the influence of ring compression on the chemica
l shifts.