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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Synthesis of beta-lactams by Ag+-induced ring expansion of 1-hydroxycyclopropylamines: A theoretical analysis
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Synthesis of beta-lactams by Ag+-induced ring expansion of 1-hydroxycyclopropylamines: A theoretical analysis

机译：Ag +诱导的1-羟基环丙胺的扩环合成β-内酰胺的理论分析

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摘要

A theoretical analysis of the silver-induced ring expansion of N-chloro-N-methyl-l-hydroxycyclopropylamine to form N-methyl-2-azetidinone, and of the Cl- elimination from this substrate without Ag+ assistance, was performed using the B3LYP method and the 6-31+G(d) basis set for C, N, O, H, and Cl atoms and the relativistic effective core pseudopotential LANL2DZ complemented with one set of f polarization functions (xi(f) = 0.473) for the Ag atom. The partial Ag+-assisted extrusion of Cl- at the rate-determining transition state provokes an important change in the nodal properties of the frontier molecular orbitals of the H3CCINCOHAg+ fragment, thus making very stabilizing HOMO-LUMO interactions between this fragment and the C2H4 moiety possible. This interaction leads to the ring opening and release of most of the strain energy, giving rise to a low energy barrier for the process. Also, by assisting the Cl- extrusion, Ag+ avoids the elimination of the hydroxyl hydrogen atom, which would provoke the fragmentation of the system instead of the formation of the beta-lactam.
机译：使用B3LYP对银诱导的N-氯-N-甲基-1-羟基环丙胺形成N-甲基-2-氮杂环丁酮的环扩环以及在没有Ag +辅助的情况下从该底物消除Cl进行了理论分析。方法，C，N，O，H和Cl原子的6-31 + G（d）基组以及相对论有效有效核心伪势LANL2DZ补充了一组f极化函数（xi（f）= 0.473）银原子。 Ag-辅助挤出的Cl-在决定速率的过渡态引发了H3CCINCOHAg +片段前沿分子轨道的节性的重要变化，从而使该片段与C2H4部分之间的非常稳定的HOMO-LUMO相互作用成为可能。这种相互作用导致大多数应变能的开环和释放，从而使该过程的能垒降低。而且，通过辅助Cl-挤出，Ag +避免了羟基氢原子的消除，这会引起系统的断裂而不是β-内酰胺的形成。

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