Methylation of 1 Followed by Methanolysis. To a
solution of 1 (2 mg) in dry acetone (1 mL) were added Me
(10 íL) and K
2
CO
(10 mg), and the mixture was stirred
overnight at room temperature and then refluxed for 2 h. After
centrifugation, the supernatant was evaporated and the reaction
mixture was directly methanolyzed in 2% NaOMe in
MeOH (1 mL) at room temperature for 8 h. After acidification
3
with acetic acid and removal of the solvent, the residue was
further treated with CH
2
N
2
in Et
O (1 mL) for 2 h and the
solvent was evaporated. The residue was redissolved in MeOH
2
2
SO
4