Phenyl isocyanate palladium-catalyzed

While simple unactivated cyclopropanes have yet to be used for [3 + 2] cycloaddition, Tsuji and coworkers have developed a palladium-catalyzed cycloaddition reaction using electron-deficient vinylcy-clopropanes. Thus, vinylcyclopropane (43) undergoes smooth cyclization with methyl acrylate in the presence of a palladium catalyst to give vinylcyclopentane (44) as a mixture of diasteroisomers (equation 35). The cycloaddition probably proceeds through the zwitterionic ( ir-allyl)palladium intermediate (45) and its stepwise reaction with the acrylate (equation 36). Enones such as cyclopentenone and methyl vinyl ketone will also react. Reaction of the same vinylcyclopropane with phenyl isocyanate produces vi-nyllactam (46) (equation 37).Some cycloaddition reactions with (cyclopropyl)Fp complexes have also been reported. However, the substrates are limited to SO2 and TCNE and the yields have not been disclosed (equation 38). ... 

Anion Source for Palladium Catalysis. The reagent serves as a source of weakly coordinating anions in the palladium-catalyzed formation of mixed phenyl ureas, a known class of commercially available herbicides, using palladium(II) acetate, copper(II) toluenesulfonate, and 2,2 -dipyridyl as the catalyst system. Other studies have suggested that use of this reagent to form palladium salts may have useful applications in the reductive carbonylation of nitroaromatic compounds to give isocyanates via initial carbamate formation (eq 2). ... 

In the palladium catalyzed reaction of racemic A -substituted vinylaziridines with isocyanates in the presence of chiral ligands higher e,es with benzyl- and methoxyphenyl isocyanate, as compared to phenyl isocyanate, are obtained. ... 

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