Intermolecular Allene Functionalization by Silver-Nitrene Catalysis
作者:Manuel R. Rodríguez、María Besora、Francisco Molina、Feliu Maseras、M. Mar Díaz-Requejo、Pedro J. Pérez
DOI:10.1021/jacs.0c04395
日期:2020.7.29
Under silver catalysis conditions, using [Tp*,BrAg]2 as the catalyst precursor, allenes react with PhI=NTs in the first example of efficient metal-mediated intermolecular nitrenetransfer to such substrates. The nature of the substituent at the allene seems crucial for the reaction outcome since arylallenes are converted into azetidine derivatives whereas methylene aziridines are the products resulting
A Convenient Stereoselective Reduction of <i>Gem</i>-Dibromides with a Combination of Dimethyl Phosphite and Potassium Carbonate
作者:Yalei Zhao、Tieqiao Chen、Xiang-Bo Wang、Li-Biao Han
DOI:10.1080/10426507.2015.1024786
日期:2015.11.2
GRAPHICAL ABSTRACT Abstract An efficient and highly stereoselectivereduction of a gem-dibromocyclopropane to the corresponding monobromocyclopropane under mild reaction conditions was developed using a combination of dimethyl phosphite and potassium carbonate. This reaction provided a simple and practical way for the synthesis of the valuable monobromocyclopropanes and β-monobromoalkenes.
Formation of Nucleophilic Allylboranes from Molecular Hydrogen and Allenes Catalyzed by a Pyridonate Borane that Displays Frustrated Lewis Pair Reactivity
allylboranes from H2 and allenes mediated by a pyridonate borane that displays frustrated‐Lewis‐pairreactivity. Experimental and computational mechanistic investigations reveal that upon H2 activation, the covalently bound pyridonate substituent becomes a datively bound pyridone ligand. Dissociation of the formed pyridone borane complex liberates Piers borane and enables a hydroboration of the allene. The allylboranes
Stereoselective Monoalkylation of α-Halocyclopropyllithiums. A Versatile Method for the Synthesis of α-Alkylcyclopropyl Acetates and Alkylidenecyclopropanes
作者:Katuzi Kitatani、Tamejiro Hiyama、Hitosi Nozaki
DOI:10.1246/bcsj.50.3288
日期:1977.12
The title carbenoids (7 and 8) prepared by the action of butyllithium on dihalocyclopropanes are smoothly methylated with methyl iodide. The product ratio of cis-methylated product (3)/trans-methylated one (4) (or endo-methylated product (5)/exo-methylated one (6) is found to depend on the aging period of the carbenoids; thermodynamic equilibration gives almost 3 or 5. This procedure has been extended to general alkylation by utilizing HMPA co-solvent. The resulting α-alkylated cyclopropyl halides are converted into allylic acetates or cyclopropyl acetates upon acetolysis and also into alkylidenecyclopropanes upon base treatment. The protonolysis of 8 gives trans- or exo-bromocyclopropanes stereoselectively.
Stereoselective One-pot Dialkylation of<i>gem</i>-Dihalocyclopropanes by Means of Dialkylcopperlithiums
作者:Katuzi Kitatani、Tamejiro Hiyama、Hitosi Nozaki
DOI:10.1246/bcsj.50.1600
日期:1977.6
(2 and 3) is established by successive treatment with dibutylcopperlithium and several electrophiles. This sequence is found to be stereochemically controllable and is successfully applied to dl-sireninsynthesis. In contrast to the reaction of dibutylcopperlithium, dimethyl- and divinylcopperlithiums convert 1,1-dibromo-2-phenylcyclopropane (1a) into 1-bromo-1-methyl- and 1-bromo-1-vinyl-2-phenylcyclopropanes