Table 3 Characteristic features for the enantiomers.
(+)-1 | (−)-1 | (+)-2 | (−)-2 | (+)-3 | (−)-3 | (+)-4 | (−)-4 | ||
|---|---|---|---|---|---|---|---|---|---|
C-8 | R | S | S | R | S | R | S | R | |
Retention time (min) a | 7.0 | 15.4 | 9.7 | 10.9 | 10.8 | 12.2 | 9.7 | 11.1 | |
Optical rotation | +25.7 | −32.9 | +43.1 | −32.0 | +68.0 | −46.3 | +106.7 | −88.9 | |
CEs | 200–205 nm | + | − | + | − | + | − | + | − |
220–260 nm | − | + | − | + | − | + | + | − | |
280–310 nm | + | − | + | − | + | − | − | + | |
