نتایج جستجو برای: boat
تعداد نتایج: 9115 فیلتر نتایج به سال:
The title compound, C(20)H(24)O(5), isolated from Rabdosia var. lophanthoides Hara, is built up from six fused rings. Cyclo-hexane ring A adopts a chair conformation, ring B exists in a screw-boat conformation and ring C adopts a boat conformation; the three five-membered rings D, E and F adopt envelope conformations.
The relative energies of the chair and boat transition states of a variety of Ireland-Claisen rearrangements were obtained by B3LYP/6-31G calculations. Theoretical results are in good agreement with experimental data and provide a quantitative analysis of the origins of boat preferences that are observed in some of these reactions.
In the title compound C18H26BrNO2S, the thia-zepine ring adopts a boat conformation. The dihedral angle between the mean planes through the benzene ring and the four C atoms making up the basal plane of the boat is 35.8 (2)°. In the crystal, inversion dimers linked by pairs of N-H⋯O hydrogen bonds generate R 2 (2)(8) loops.
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