5505
(or revision) of the structure previously assigned to natural stigmatellin. Results along this line
will be published in due course.
References
1. Adje, N.; Domon, L.; Vogeleisen-Mutterer, F.; Uguen, D. Tetrahedron Lett. 2000, 41, 5495±5499.
2. Ho¯e, G.; Kunze, B.; Zorzin, C.; Reichenbach, H. Liebigs Ann. Chem. 1984, 1883±1904.
3. (a) Bradley, W.; Robinson, R.; Schwarzenbach, G. J. Chem. Soc. 1930, 793±817; (b) Syper, L. Synthesis 1989, 167±
172.
4. Hirao, I.; Yamaguchi, M.; Hamada, M. Synthesis 1984, 1076±1078. Protocol for the 3±6c conversion: To a
suspension of NaH (91 mg, 2.27 mmol) in DMSO (12 ml) was added the ester 3 (560 mg, 0.85 mmol), diluted
with DMSO (5 ml). After 3 hours stirring at rt, the reaction mixture was slowly poured into a well-stirred, cooled
(0ꢀC), saturated solution of oxalic acid in water (30 ml). The resulting mixture was extracted with AcOEt (4Â20
ml) and the pooled organic extracts were washed with water (50 ml), and brine (3Â25 ml), then dried (MgSO4).
The residue left by evaporation of the solvents was taken up in AcOH (4 ml) and a few drops of conc. HCl were
added. After 1.5 hours stirring, the resulting yellow solution was evaporated to dryness (rotoevaporator) and the
residue was dissolved in AcOEt (20 ml). This was followed by washing with water (20 ml) and the resulting
aqueous layer was back extracted with AcOEt (2Â10 ml). The resulting, pooled, organic extracts were dried
(MgSO4), and evaporated to give an oil which was treated by TBAF (500 mg) in CH2Cl2 (10 ml). After 1 hour, the
resulting solution was thoroughly washed with brine (5Â10 ml), and dried (MgSO4). Evaporation of the solvents
gave an oil which was chromatographed on 60 silica gel (hexane/AcOEt) to aord the pure compound 6c as a
colourless oil (337 mg, 81%). The corresponding acetate of 4b gave the chromone 2b in moderate yield (49%) in
these conditions.
5. (a) Crimmins, M. T.; King, B. W. J. Am. Chem. Soc. 1998, 120, 9084±9085; (b) Maryano, B. E.; Reitz, A. B.
Chem. Reviews 1988, 84, 863±927.
6. Selected data: compound 8a: m.p. 123ꢀC; compound 8b: m.p. 68ꢀC; compound 8e: m.p. 54ꢀC; compound 4a: m.p.
128ꢀC; compound 4c: m.p. 132ꢀC; compound 4b: m.p. 68ꢀC; compound 10b: [ꢀ]D ^47.9 (c 2); compound 10c:
[a]D ^22 (c 3.5); compound 10d: [a]D +4 (c 4.6); compound 5e: [a]D +8 (c 2.8); compound 5c: [a]d +2.8 (c 4.5);
compound 3: 1H NMR: 0.92 (d, J=6.8 Hz, 6H), 1.05±1.19 (m, 24H), 1.36±1.49 (m, 1H), 1.64±1.84 (m, 3H), 2.31±
2.5 (m, 2H), 2.79 (q, J=7.3 Hz, 2H), 2.85 (m, 1H), 3.41 (s, 3H), 3.71 (m, 2H), 3.82 (s, 3H), 3.89 (s, 3H), 4.92 (s,
2H), 6.39 (s, 1H), 7.35 (m, 5H); 13C NMR: 8.2, 12.1, 14.9, 16.9, 18.2, 24.5, 34.5, 37.6, 38.8, 56.2, 61.3, 65.2, 75.1,
87.6, 94.5, 117.5, 127.9, 128.1, 128.4, 134.5, 137.7, 142.2, 153.5, 155.1, 171.9, 202.8; compound 6c: 1H NMR: 0.91
(d, J=7 Hz, 3H), 1 (d, J=6.7 Hz, 3H), 1.46±1.65 (m, 1H), 1.65±1.96 (m, 3H), 1.97 (s, 3H), 2.39±2.82 (m, 2H), 2.83
(m, 1H), 3.39 (s, 3H), 3.5±3.71 (m, 2H), 3.92 (s, 6H), 5 (s, 2H), 6.38 (s, 1H), 7.28±7.48 (m, 5H); 13C NMR: 9.6,
15.6, 16.8, 29.1, 30, 35.8, 37, 56.3, 56.5, 61.4, 66.2, 75.7, 91.8, 92.1, 108.1, 117, 128.2, 128.3, 128.4, 137.5, 141.5,
1
152.1, 156.1, 156.4, 162.3, 177.5. H and 13C NMR in CDCl3 at 200 and 50 MHz, respectively. [ꢀ]D values in
CH2Cl2. All new compounds have given satisfactory elemental (C, H) analyses. The results presented herein are
taken in part from the thesis of L. Domon, Strasbourg (1999).