Hammett Analyses of Halocarbene–Halocarbanion Equilibria
摘要:
Substituted arylchlorocarbenes (X = H, p-Cl, p-CF3, p-F, m-Cl) reacted reversibly with Cl- in dichloroethane to form the corresponding aryldichloromethide carbanions. Equilibrium constants and rate constants for the forward and reverse reactions were correlated by the Hammett equation. DFT methods were used to compute equilibrium constants and electronic absorption spectra.
Carbon Atom Insertion into Pyrroles and Indoles Promoted by Chlorodiazirines
作者:Balu D. Dherange、Patrick Q. Kelly、Jordan P. Liles、Matthew S. Sigman、Mark D. Levin
DOI:10.1021/jacs.1c06287
日期:2021.8.4
calculations supporting a selectivity-determining cyclopropanation step. Computations surprisingly indicate that the stereochemistry of cyclopropanation is of little consequence to the subsequent electrocyclicringopening that forges the pyridine core, due to a compensatory homoaromatic stabilization that counterbalances orbital-controlled torquoselectivity effects. The utility of this skeletal transform is
Systematic Repression of β-Silyl Carbocation Stabilization
作者:Xavier Creary、Elizabeth D. Kochly
DOI:10.1021/jo802722z
日期:2009.3.6
intermediate cyclopropyl cation undergoes substantial ring opening since β-silyl stabilization is not large (calculated stabilization energy of 12 kcal/mol). Solvolysis rates of 2-trimethylsilylbenzocyclobutyl derivatives are not significantly enhanced by the β-trimethylsilyl group. β-Silyl stabilization of benzocyclobutenyl carbocations generated in solution has been effectively eliminated due to antiaromatic
Unified Access to Pyrimidines and Quinazolines Enabled by N–N Cleaving Carbon Atom Insertion
作者:Ethan E. Hyland、Patrick Q. Kelly、Alexander M. McKillop、Balu D. Dherange、Mark D. Levin
DOI:10.1021/jacs.2c09616
日期:2022.10.26
transformations with the capacity to modify such molecular skeletons with modularity remain highly desirable. Ring expansions that enable interconversion of privileged heterocyclic motifs are especially interesting in this regard. As such, the known mechanisms for ring expansion and contraction determine the classes of heterocycle amenable to skeletal editing. Herein, we report a reaction that selectively cleaves
Reactions of Frustrated Lewis Pairs with Chloro‐Diazirines: Cleavage of N=N Double Bonds
作者:Dipendu Mandal、Ting Chen、Zheng‐Wang Qu、Stefan Grimme、Douglas W. Stephan
DOI:10.1002/anie.202209241
日期:2022.9.12
lead to rapid loss of N2, reactions of phosphine/borane FLPs with chlorodiazirines prompt N=N double bond cleavage, affording linked phosphinimide/amidoborate zwitterions of the general form R3PNC(Ar)NR′BX(C6F5)2. A detailed DFT mechanistic study shows that these reactions proceed via FLP addition to the N=N bond.
虽然已知 FLP 与重氮甲烷的反应会导致 N 2的快速损失,但膦/硼烷 FLP 与氯二氮丙啶的反应会促进 N=N 双键断裂,从而提供通式 R 3 PNC(Ar) 的连接的膦酰亚胺/氨基硼酸盐两性离子NR′BX(C 6 F 5 ) 2 。详细的 DFT 机理研究表明,这些反应通过 FLP 加成到 N=N 键上进行。
Hammett Analyses of Halocarbene–Halocarbanion Equilibria
作者:Lei Wang、Robert A. Moss、Karsten Krogh-Jespersen
DOI:10.1021/ol400698y
日期:2013.4.19
Substituted arylchlorocarbenes (X = H, p-Cl, p-CF3, p-F, m-Cl) reacted reversibly with Cl- in dichloroethane to form the corresponding aryldichloromethide carbanions. Equilibrium constants and rate constants for the forward and reverse reactions were correlated by the Hammett equation. DFT methods were used to compute equilibrium constants and electronic absorption spectra.