shows a single resonance at τ = +2·7 consistent with a formulation of the complex as a monomeric cyclobutadiene co-ordination compound. IR spectra of this compound and the analogous ones with NO3− and BF4− anions have been discussed in relation to possible structures of this type. It is concluded that the crystalline complexes probably have (C4H4Ag)+ cations of symmetry C2v or C2h.
A Metal-Free Cyclobutadiene Reagent for Intermolecular [4 + 2] Cycloadditions
作者:Benjamin R. Boswell、Carl M. F. Mansson、Gabrielle E. Cabrera、Calvin R. Hansen、Allen G. Oliver、Noah Z. Burns
DOI:10.1021/jacs.3c01591
日期:2023.3.15
due to its lengthy synthesis that generates hazardous byproducts including excess heavy metals. Herein, we report a scalable, metal-free cyclobutadiene reagent, diethyldiazabicyclohexene dicarboxylate, and explore its intermolecular [4 + 2] cycloaddition with various electron-deficient alkenes. We also demonstrate its utility in a three-step synthesis of dipiperamide G and a diverse array of product derivatizations
环丁二烯是一种高反应性抗芳烃,60 多年来一直令化学家着迷。然而,它在化学合成中的制备和使用很少,部分原因是它的合成过程冗长,会产生包括过量重金属在内的有害副产物。在此,我们报道了一种可扩展的、不含金属的环丁二烯试剂二乙基二氮杂双环己烯二羧酸盐,并探索了它与各种缺电子烯烃的分子间 [4 + 2] 环加成反应。我们还证明了它在双哌酰胺 G 的三步合成和包括溴环丁二烯在内的多种产品衍生化中的实用性。
Photochemical precursor to cyclobutadiene
作者:Robert Dennis Miller、E. Hedaya
DOI:10.1021/ja01047a047
日期:1969.9
The dimeric structure of [C4H4AgC1O4]n: A reinvestigation of the nuclear magnetic resonance spectrum