Steric Consequences on the Conformation of Medium-Sized Rings: Solution NMR, Solid-State Crystallographic, <i>ab Initio</i> Molecular Orbital Calculations, and Molecular Mechanics Studies on Substituted Eight-Membered Organosilicon Ring Systems<sup>1</sup>
作者:Lilibeth P. Burke、Anthony D. DeBellis、Herman Fuhrer、Hansrudolf Meier、Stephen D. Pastor、Grety Rihs、Guenther Rist、Ronald K. Rodebaugh、Sai P. Shum
DOI:10.1021/ja9711829
日期:1997.9.1
The conformation of the eight-membered membered 12H-dibenzo[d,g][1,3,2]dioxasilocin ring system was investigated both in the solid-state by X-ray crystallography and in solution by NOE experiments. Ab initio Hartree−Fock calculations were performed to locate all stationary points for the unsubstituted 12H-dibenzo[d,g][1,3,2]dioxasilocin ring system. The MM2* force field was parametrized to reproduce
八元元 12H-二苯并[d,g][1,3,2]dioxasilocin 环系统的构象通过 X 射线晶体学在固态和通过 NOE 实验在溶液中进行了研究。执行从头算 Hartree-Fock 计算以定位未取代的 12H-二苯并[d,g][1,3,2]dioxasilocin 环系统的所有驻点。MM2* 力场被参数化以重现我们的 ab initio 结果,并将这些数据与实验数据进行比较。确定了构象交换的过渡态。C(12) 碳原子或硅上甲基取代基的伪赤道偏好大于 2,4,8,10-四叔丁基中船椅和扭曲船构象之间的能量差异取代的 12H-二苯并[d,g][1,3,2]二恶唑菌素。