Unsymmetrical 1,1-diborated multisubstituted sp<sup>3</sup>-carbons formed via a metal-free concerted-asynchronous mechanism
作者:Ana B. Cuenca、Jessica Cid、Diego García-López、Jorge J. Carbó、Elena Fernández
DOI:10.1039/c5ob01523e
日期:——
unsymmetrical 1,1-diboration of diazo compounds, formed in situ from aldehydes and cyclic and non-cyclic ketones, in the absence of any transition metal complex. The heterolytic cleavage of the mixed diboron reagent, Bpin–Bdan, and the formation of two geminal C–Bpin and C–Bdan bonds has been rationalised based on DFT calculations to occur via a concerted-asynchronous mechanism. Diastereoselection is attained
A matter of catalyst: Azole compounds can be directly alkylated with N‐tosylhydrazones that bear unactivatedalkylgroups (see scheme; phen=1,10‐phenanthroline, Ts=p‐toluenesulfonyl). Nickel catalysis enables the introduction of simple secondary alkyl chains into benzoxazole compounds, whereas the alkylation of 5‐aryloxazoles and benzothiazole is possible by using a cobalt catalyst.
Investigations on Superbase Mediated Reactivity of N‐Tosylhydrazones with Aza‐ortho‐Quinone Methide Precursors
作者:Rahul P.、Arunkumar T. K.、Seena Sebastian、Haritha Raveendran、Sunil Varughese、Jomon Mathew、Jubi John
DOI:10.1002/ejoc.202400151
日期:2024.5.13
We have encountered a superbase‐mediated chemoselective reaction of N‐tosylhydrazones with aza‐ortho‐quinone methide precursors. When tosylhydrazone was treated with ortho‐aminobenzyl alcohol in super basic conditions (KOH+DMSO), we observed the formation of 2‐substituted quinoline. The reaction was found to be general, and by this method, mono‐, di‐ and tri‐substituted quinolines could be made. We could prove experimentally and theoretically that the reaction proceeded via the formation of an azine from the basic decomposition of N‐tosylhydrazones. Finally, the reaction of tosylhydrazone with N‐(2‐(chloromethyl)phenyl)‐4‐methylbenzenesulfonamide (aza‐ortho‐quinone methide precursor) under super basic conditions afforded hydrazine substituted sulfonamides.