using reversed-phase chromatography. The initial mobile
phase gradient applied to isolating compounds 1
and 2 from fraction 15 was based on the elution profile
observed during the preparative HPLC separation that
afforded this fraction. An HPLC method was quickly
developed which started at an isocratic gradient of
32% acetonitrile in water for 33.0 min, followed by a linear
gradient of acetonitrile from 32% to 36% over 3.0
min. The final isocratic gradient of 36% acetonitrile in
water was run for 5.0 min followed by a 95% acetonitrile
in water gradient for 5.0 min. This afforded compounds
1 (70 lg, Rt = 31.5 min) and 2 (15 lg, Rt = 32.9 min).