Straightforward formation of carbocations from tertiary carboxylic acids via CO release at room temperature

We report an unprecedented mode of reactivity of carboxylic acids. A series of tertiary carboxylic acids, containing at least one phenyl α-substituent, undergo loss of carbon monoxide at room temperature (295 K), by a one pot reaction with 0.5-1 molar equivalents of WCl₆ in dichloromethane. A plausible mechanism for the Ph₃CCO₂H/WCl₆ reaction, leading to [CPh₃][WOCl₅] and Ph₃CCl, is proposed on the basis of DFT calculations. The analogous reactions involving CEt(Ph)₂CO₂H, CMe(Ph)₂CO₂H and CMe₂(Ph)CO₂H selectively afforded stable hydrocarbons (alkene or indene, depending on the case), apparently resulting from the rearrangement of elusive tertiary carbocations.

The reactions of α-amino acids and α-amino acid esters with high valent transition metal halides: synthesis of coordination complexes, activation processes and stabilization of α-ammonium acylchloride cations

We describe the synthesis of rare coordination compounds of early transition metals with α-amino acids and α-amino acid esters, the unusual C–C dimerization ofl-proline, and the stabilization of reactive α-ammonium acylchloride cations.

One pot conversion of benzophenone imine into the relevant 2-aza-allenium

Interaction of common imines with WCl₆ in organic solvents revealed very unusual features in the context of imine chemistry. Ph₂C[double bond, length as m-dash]NH was converted in one pot into the 2-aza-allenium species [Ph₂C[double bond, length as m-dash]N[double bond, length as m-dash]CPh₂]⁺via N₂ release, with [Ph₂C[double bond, length as m-dash]NH₂]⁺ being a co-product. PhCH[double bond, length as m-dash]N^tBu underwent C-H bond activation resulting in the formation of [C[triple bond, length as m-dash]N] containing derivatives, together with [PhCH[double bond, length as m-dash]NH^tBu]⁺.

The chemistry of high valent tungsten chlorides with N-substituted ureas, including urea self-protonation reactions triggered by WCl6

N-Substituted ureas are oxidized by WCl₆in dichloromethane, resulting in protonated urea saltsviaactivation of C–H and/or N–H bonds.