Ahmed Benharref

Oxydation et addition des dihalocarbènes sur le β-himachalène

Resume Reaction of β-himachalene with one equivalent of dihalocarbene, KMnO 4 or m -CPBA gives regio- and stereospecifically one product resulting from the attack of the C6 C7 double bond. The molecular structure shows that this attack occurs on the α face of this double bond.

Bioactive triterpene derivatives from latex of two Euphorbia species

We have investigated the antifeedant and toxic effects of 23 semisynthetic terpenoid derivatives obtained through chemical modifications of the major components of Euphorbia resinifera (alpha-euphol and alpha-euphorbol) and E. officinarum (obtusifoliol and 31-norlanostenol) latex on several insect species (Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi), their selective cytotoxicity on insect Sf9 and mammalian CHO cells and their phytotoxic effects on Lactuca sativa. The conversions focused mainly on positions 3,7,11, and 24 with several oxidizing agents. A total of 18 compounds affected S. littoralis growth (IGR). Our results support the importance of the C-3 substituent, suggest the involvement of the C-7 substituent and indicate that the C-3 hydroxyl is not essential for the IGR effect. Overall, Sf9 cells were more sensitive to the active compounds than CHO cells. All of these compounds had non selective moderate phytotoxic effects on radicle elongation of L. sativa.

Optimization of Allylic Oxidation of (1S,3R,8R)‐2,2‐Dichloro‐3,7,7,10‐tetramethyltricyclo[6,4,0,01,3]dodec‐9‐ene

Abstract The allylic oxidation of (1S,3R,8R)‐2,2‐dichloro‐3,7,7,10‐tetramethyltricyclo[6,4,0,01,3]dodec‐9‐ene into the corresponding enone with N‐bromosuccinimide (NBS), CrO3 and t‐BuOOH has been studied. A good yield and high selectivity were obtained in the presence of t‐BuOOH and a copper catalyst.

Regio and Stereoselective Epoxidation of Cis-and Trans-Himachalenes

Abstract As part of our program on valorisation of moroccan essential oils, we have synthesized, from cis-and trans-himachalenes extracted from cedrus Atlantica, mono and diepoxides in 2,3 and 7,13 or 7,8 position whose configurations were established.

REGIOSPECIFIC SYNTHESIS OF A NEW CHIRAL N-SUBSTITUTED PYRAZOLE USING A SESQUITERPENE HYDROCARBON

ABSTRACT Treatment of β-enaminone 4 with 2-hydrazinopyridine gives a regiospecific formation N-substituted pyrazole 6. Enaminone 4 was prepared for the first time by reacting enone 3 with sodium azide in acidic medium. The structural assignment of 2, 3, 4, 5 and 6 is based upon 1H, 13C NMR spectroscopy, mass spectrometry and X-ray structural analyses.

(1S,3R,8R,9R,10S)-2,2-Dibromo-3,7,7,10-tetra­methyl-9β,10β-ep­oxy-3,7,7,10-tetra­methyl­tricyclo­[6.4.0.01,3]dodeca­ne

The title compound, C16H24Br2O, was synthesized from β-himachalene (3,5,5,9-tetramethyl-2,4a,5,6,7,8-hexahydro-1H-benzocycloheptene), which was isolated from the essential oil of the Atlas cedar (Cedrus atlantica). The molecule contains fused six- and seven-membered rings, each linked to a three-membered ring. The six-membered ring has a half-chair conformation, while the seven-membered ring displays a chair conformation. The dihedral angle between the mean planes through the six- and seven-membered rings is 39.55 (12)°. The two three-membered rings, linked to the six- and seven-membered rings, are nearly perpendicular to the six-membered ring, making dihedral angles of 78.6 (2) and 80.5 (2)°, respectively. The absolute structure was established unambiguously from anomalous dispersion effects. In the crystal, each molecule is linked to its symmetry-equivalent partner by C—H⋯O hydrogen bonds, forming zigzag chains parallel to [100].

(1S,3R,8R,9S,11R)-2,2,10,10-Tetra­chloro-3,7,7,11-tetra­methyl­tetra­cyclo­[6.5.0.01,3.09,11]trideca­ne

The title compound, C17H26Cl2, was synthesized from β-himachalene (3,5,5,9-tetramethyl-2,4a,5,6,7,8-hexahydro-1H-benzocycloheptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The asymmetric unit contains two independent molecules with similar conformations. Each molecule is built up from fused six- and seven-membered rings and two three-membered rings from the reaction of β-himachalene with dichlorocarbene. In both molecules, the six-membered ring has a half-chair conformation, whereas the seven-membered ring displays a boat conformation. The absolute configuration was established from anomalous dispersion effects.

Prenatal exposure to tobacco extract containing nicotinic alkaloids produces morphological and behavioral changes in newborn rats

Tobacco exposure is not only a health concern for adults but has also been shown to exert deleterious effects on the health of the fetus, newborn, child, and adolescent. Decreased cognitive function, lower Intellectual Quotient (IQ) and deficits in learning and memory in children have been associated with maternal smoking during pregnancy. In this study, we have studied the effect of a tobacco plant extract on the growth and development in the rat. The extract contained relative proportions of alkaloids, including nicotine, purified by chemical separation. Pregnant rats received oral doses of either control (NaCl) or tobacco extract during the entire gestational period. Offspring length and body weight were measured. Each day, the offspring were observed for the following physical parameters: hair growth, incisor eruption and eye opening. The day of appearance of these developments was recorded. Before weaning, the offspring were examined to test their cliff avoidance response (6 postnatal day (PN)), surface righting reflex (05, 07, 13 postnatal day), swimming development (10, 12 postnatal day), negative geotaxis response (7,9,13 and 17 postnatal day) and jumping down choice cage (15, 17 postnatal day). Administration of tobacco extract to dams during the entire gestation period affects behavior and development in pups. The observed effects were a delay in opening eyes, incisor eruption and hair appearance, behavioral developments and an alteration in the rate of success behavior. However, in the jumping down choice cage test there was no difference compared to control animals. The results suggest that tobacco extract has a significant effect on the development of behavioral patterns, orientation and motor coordination and function. They also suggest significant growth retardation and teratogenic effects.

Crystal structure of 1-isopropyl-4,7-dimethyl-3-nitro­naphthalene

The title compound, C15H17NO2, was synthesized from a mixture of α-himachalene (2-methylene-6,6,9-trimethylbicyclo[5.4.01,7]undec-8-ene) and β-himachalene (2,6,6,9-tetramethylbicyclo[5.4.01,7]undeca-1,8-diene), which were isolated from an oil of the Atlas cedar (Cedrus Atlantica). The naphthalene ring system makes dihedral angles of 68.6 (2) and 44.3 (2)°, respectively, with its attached isopropyl C/C/C plane and the nitro group. In the crystal, molecules held together by a C—H⋯O interaction, forming a chain along [-101].

(1S,3R,8R,9S,11R)-2,2,10,10-Tetrachloro-3,7,7,11-tetramethyltetracyclo[6.5.0.01,3.09,11]tridecane

The title compound, C17H24Cl4, was synthesized from β-himachalene (3,5,5,9-tetramethyl-2,4a,5,6,7,8-hexahydro-1H-benzocycloheptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The molecule is built up from fused six- and seven-membered rings and two three-membered rings from the reaction of β-himachalene with dichlorocarbene. The six-membered ring shows a chair conformation, whereas the seven-membered ring displays a boat conformation.