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The aim of this work is to study the influence of the nature and position of substitution at allyl benzene on the regioselectivity of the hydrosilylation reaction. We studied hydrosilylation of the various allyl derivatives with cyclic siloxane, D4H, and linears hydrosilylating agents, 1,1,3,3-tetramethyldisiloxane and MDHM, in the presence of platinum-based catalysts (Karstedt catalyst, platinum black). We also show the effects of the amount of catalyst on the conversion. Moreover, the influence on the temperature on catalytic activity and selectivity of the hydrosilylation reaction was explained. All new compounds were characterized by 1H, 13C, 29Si NMR and HRMS as well.

The ten-membered ring in the title molecule, C25H29ClN2O7, adopts an approximate chair–chair conformation, whereas the five-membered furan and pyrazole rings display envelope conformations. The mean plane of the furan ring is almost perpendicular to that of the pyrazole ring, as indicated by the dihedral angle between them of 86.45 (9)°. The pyrazole ring is slightly inclined to the plane of the attached phenyl ring, subtending a dihedral angle of 16.88 (8)°. The conformation of the molecule is stabilized by six intramolecular hydrogen bonds and crystal cohesion is ensured by five C—H...O hydrogen bonds, in addition to C—H...π interactions.

The ten-membered ring in the title mol-ecule, C

In the title compound, C22H25NO5·H2O, the ten-membered ring displays an approximate chair–chair conformation, whereas the five-membered furan ring has an envelope conformation, with the C atom of the methine group adjacent to the spiro C atom as the flap. The isoxazole ring is almost planar and its plane is slightly inclined to the plane of the attached phenyl ring. The mean plane of the furan ring is nearly perpendicular to that of the isoxazole ring, as indicated by the dihedral angle between them of 89.39 (12)°. In the crystal, the organic molecules are linked into [010] chains by O—H...O hydrogen bonds. The water molecule forms O—H...O and O—H...N hydrogen bonds and a weak C—H...O interaction is also observed. Together, these lead to a three-dimensional network.

A series of novel spiropyrazoles and spiroisoxazolines was efficiently synthesized. Structural modifications were performed at the C-9 and C-13 positions of 9α- and 9β-hydroxyparthenolide, which were isolated from the aerial parts of Anvillea radiata. The structures and stereochemistry of the cycloadducts were fully established by spectroscopic methods including X-ray diffraction data.