(3S)-Acetyl-24-methyl-elemo-lanosta-8,24(31)-diene-7,11-dione

N. Mazoir, A. Auhmani, My. Y. Ait Itto and A. Benharref

Laboratoire de Chimie des Substances Naturelles et des Hétérocycles, Université Cadi Ayyad, Faculté des Sciences Semlalia, B.P 2390. Marrakech. Maroc. E-mail: [email protected]

Received: 24 October 2003 / Accepted: 11 February 2004 / Published: 24 February 2004

To a solution of 1¹ (1g, 2.07 mmol) in 20 ml of acetone, was added (0.62g, 6.22 mmol) of chromic anhydride². The mixture was maintained at 0°C during 24 h, and washed with 20ml of cold water. Extracted with ethyl acetate, the organic layer was dried over Na₂SO₄ , and evaporated under reduced pressure. The residue was purified on a silica gel column using hexane/EtOAc (99/1) as eluant to give 2  (0.75g, 70%).

Mp: 139-140 °C (Hexane)

MS (EI, 70eV) : 510 (M^+.).

¹H NMR (300 MHz, CDCl₃) d(ppm): 4.55 (dd, J₁=12, J₂= 4Hz , H-3); 2.05 (s, 3H of acetyl group); 1.22 and 1.25 (2s, 3H-26, 3H-27); 4.63 and 4.69 (2S, 2H-31).

¹³C NMR (75 MHz, CDCl₃) d(ppm): 80.70 C-3 ; 171.09 CO of acetyl group; 200.00;  202.50 C7 and C11 ; 150.00; 155.00 C8 and C9 ; 155.50 C-14 ; 106.50 C-31, IR n (cm^-1): 1700 cm^-1_.

References

1. Benharref, A.; Lavergne, J.-P. Bull. Soc. Chim. Fr. 1985, 965.

2. Muzart, J., Tetrahedron Letters, 1987, 28, 4665-4668.

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