Table 1:
Chemical shifts of tertiary (C
t
) and quaternary (C
q
) carbon atoms.
Compound
δ
C
in ppm (CDCl
3
, 75.47 MHz)
C-4 (1,5-isomer)
C-5 (1,4-isomer)
(1)
123.24 (C
t
)
140.20 (C
q
)
(2)
144.20 (C
q
)
120.32 (C
t
)