... Chemistry The camptothecin analogues were prepared by total synthesis. ... constants (RS)-1"' 63 163 148 128 128 114 >3.7 are reported in hertz and chemical shifts in ... and 25d" 26 >189( ) 17; / 151 135 > 9“ 6 toluene were dried over molecular sieves (4 A) (Wako Chemicals). ...