Notes
Journal of Natural Products, 2005, Vol. 68, No. 9 1411
CO) were extracted with CHCl3 for spectroscopy (Merck ref.
1.02447, 3 × 300 mL) at room temperature for 8 days.
Filtration and evaporation (470 mbar, 40 °C) of the solvent
gave a residue (3.07 g). A part (1.5 g) of this extract was
subjected to chromatography (Si gel 230-400 mesh column,
80 g) eluting with petroleum ether (PRA grade, 99.5%
C6 isomers, free of Me2CO) and petroleum ether-EtOAc
(CHROMASOLV Plus, for HLPC, 99.9%, free of acetone) 9:1,
4:1, and 1:1 mixtures. The fractions eluted with 4:1 petroleum
ether-EtOAc contained compounds with polarities similar
(TLC) to that of 1. Alternately, the remaining sample (1.57 g)
of the total extract was digested with 9:1 petroleum ether-
EtOAc (30 mL) at room temperature for 5 h. The soluble
fraction was very similar (TLC) to that obtained by chroma-
tography. Both these fractions were subjected to HPLC
analysis (see General Experimental Procedures), and in both
cases a peak with a retention time 2.5 min (identical to that
of an authentic sample of 1) was observed. HPLC of a mixture
of authentic 1 and each one of the above fractions showed an
enhanced peak at tR 2.5 min. The mobile phase (9:1 acetoni-
trile-water) for the HPLC analyses was free of Me2CO
(analytical grade solvents).
Treatment of Cryptotanshinone (3) with Acetone
under Basic Conditions. To a stirred solution of 38,9 (23 mg,
0.077 mmol) in EtOH (8 mL) were successively added Me2CO
(2 mL) and an EtOH solution of KOH (10%, w/v, 2 mL, 3.56
mmol), and the reaction mixture was stirred at room temper-
ature for 8 min. Then, water (20 mL) was added and the
mixture was extracted with CH2Cl2 (4 × 15 mL). The extracts
were dried (Na2SO4) and filtered, and the solvents were
removed, giving a residue (23 mg), which was chromato-
graphed (Si gel 230-400 mesh column, 7 g, eluted with 4:1
petroleum ether-EtOAc), yielding pure 2 (17 mg, 0.048 mmol,
61.8%), less polar (TLC, 4:1 petroleum ether-EtOAc as eluent)
than the starting material (3).
mmol) at room temperature for 48 h, the starting material (5)
was recovered unchanged.
Acknowledgment. We thank Dr. E. S. Martins, “Centro
de Botaˆnica do Instituto de Investigac¸a˜o Cient´ıfica Tropical”,
Lisbon, Portugal, for the identification of the plant material.
The authors are indebted to Miss M. D. Casado and Mrs. M.
Plaza, “Centro de Qu´ımica Orga´nica Manuel Lora-Tamayo”,
CSIC, Madrid, Spain, for technical assistance. We thank H.
Vila Real and J. Bento Marques, undergraduate students of
the Faculty of Pharmacy, Lisbon University (Search Project I
Course), for their valuable and enthusiastic aid in the plant
extraction and chromatographic processes. This work was
supported by funds from the Spanish “Comisio´n Interminis-
terial de Ciencia y Tecnolog´ıa” (CICYT, grant no. 5653) and
from the Portuguese FCT (I&D no. 8/94), POCTI (QCA III),
and Feder Projects. One of us (C.G.-M.) thanks the FCT for a
fellowship (Praxis XXI/BD/18046/98).
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(32) Signals marked with an asterisk appeared as overlapped or partially
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Attempts at Obtaining Michael Adducts from 7r-
Acetoxyroyleanone (5) and Acetone. Treatment of 5,23-25
as described above for obtaining 2, yielded the starting
material (5) and minute amounts (>4%) of horminone (6),24,25
identified by comparison (TLC, UV, and MS) with an authentic
sample.5
When a solution of 5 (39 mg, 0.026 mmol) in MeOH-Me2-
CO (2:1, v/v, 30 mL) was treated with K-t-BuO (19 mg, 0.168
NP0580457