REACTION OF QUINONEIMINES WITH KETENES

A molecular electron density theory study of the [3 + 2] cycloaddition reaction of nitrones with ketenes.

The [3 + 2] cycloaddition (32CA) reaction between nitrones and ketenes has been studied within the Molecular Electron Density Theory (MEDT) at the Density Functional Theory (DFT) MPWB1K/6-311G(d,p) computational level. Analysis of the conceptual DFT reactivity indices allows the explanation of the reactivity, and the chemo- and regioselectivity experimentally observed. The particular mechanism ...

A silver(I)-catalyzed tandem reaction of 2-alkynylbenzaldoximes with ketenes.

A novel and unexpected reaction of 2-alkynylbenzaldoximes with ketenes in the presence of silver triflate (10 mol%) under mild conditions is discovered. This reaction proceeds through 6-endo-cyclization, [3 + 2] cycloaddition, and rearrangement, leading to isoquinoline derivatives in moderate to good yields.

Generation and Trapping of Ketenes in Flow

Ketenes were generated by the thermolysis of alkoxyalkynes under flow conditions, and then trapped with amines and alcohols to cleanly give amides and esters. For a 10 min reaction time, temperatures of 180, 160, and 140 °C were required for >95 % conversion of EtO, iPrO, and tBuO alkoxyalkynes, respectively. Variation of the temperature and flow rate with inline monitoring of the output by IR ...

Nucleophilicity toward ketenes: rate constants for addition of amines to aryl ketenes in acetonitrile solution.

Second-order rate constants (k(Nu)) have been measured for the addition of amines to ketenes 4-6 in acetonitrile solution by the laser flash photolysis technique. These ketenes are formed from a photochemical Wolff rearrangement of diazoketones 1-3, respectively. For all diazoketones studied, the presence of amines as nucleophiles in the reaction medium results in the formation of an intermedia...

Rhodium-catalyzed linear codimerization and cycloaddition of ketenes with alkynes.

A novel rhodium-catalyzed linear codimerization of alkyl phenyl ketenes with internal alkynes to dienones and a novel synthesis of furans by an unusual cycloaddition of diaryl ketenes with internal alkynes have been developed. These reactions proceed smoothly with the same rhodium catalyst, RhCl(PPh(3))(3), and are highly dependent on the structure and reactivity of the starting ketenes.

Annulation Reactions of ( Trialkylsilyl ) Ketenes : Synthesis of Substituted