Rhodium perfluorobutyramide

Rhodium perfluorobutyramide, (pfm)4Rh2, has been shown to catalyse the conversion of alkenes to trichloroethoxysulfonyl, nosyl, and tosyl aziridines on reaction with the corresponding sulfonamide and PhI(OAc)2.97... 

In addition to fluorous catalysis, the preparation of fluorous catalyst itself can benefit from microwave-assisted synthesis. The Wood group reported the preparation of rhodium perfluorobutyramide (Rh2(pfm)4), a catalyst for... 

The perfluoroacetamide catalysts, rhodium(II) trifluoroacetamidate [Rh2(tfm)4] and rhodium(II) perfluorobutyramidate [Rh2(pfbm)4], are interesting hybrid molecules that combine the features of the amidate and perfluorinated ligands. In early studies, these catalysts were shown to prefer insertion over cycloaddition [30]. They also demonstrated a preference for oxindole formation via aromatic C-H insertion [31], even over other potential reactions [86]. In still another example, rhodium(II) perfluorobutyramidate showed a preference for aromatic C-H insertion over pyridinium ylide formation, in the synthesis of an indole nucleus [32]. Despite this demonstrated propensity for aromatic insertion, the perfluorobutyramidate was shown to be an efficient catalyst for the generation of isomtinchnones [33]. The chemoselectivity of this catalyst was further demonstrated in the cycloaddition with ethyl vinyl ethers [87] and its application to diversity-oriented synthesis [88]. However, it was demonstrated that while diazo imides do form isomtinchnones under these conditions, the selectivity was completely reversed from that observed with rhodium(II) acetate [89, 90]. 

As Moody and co-workers (173) discovered, isomtinchnones can occasionally form even when they are not the desired product Thus, these workers inadvertently obtained an oxazolidinedione via an isomtinchnone rather than the desired oxoindo-line when a diazo compound was treated with rhodium(II) perfluorobutyramide in their studies leading ultimately to a synthesis of the marine alkaloid convolutamy-dine C. 

The a-(phenylsulfonyl)- and a-(ethoxyphosphoryl)-diazoacetamides 84d/e are exclusively converted to formal aromatic C-H insertion products 86d/e upon rhodium(II) perfluorobutyramide (Rh2(pfb)2> catalysis. The unsubstituted diazoacetamide 84a affords exclusively the Buchner ring expansion product 85a, and the Buchner reaction remains the favorable pathway with diazo substrates 84b/c, which bear relatively small a-substituents. The predominant formation of the Buchner products in these cases can be rationalized on the basis of steric effects. Various isoquinolinones are synthesized intramolecularly via six-membered ring formation with high regioelectivity and diastereoselectivity, while averting the common Buchner reaction. 

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