Fluorous solvents, Diels—Alder reactions with

Extensions of the triflate catalyst include the use of versions with fluorinated ponytails such as [Sc C(S02C8Fi7)3 3] for use in fluorous phase Diels-Alder reactions (fluorinated solvent.)... 

Bayardon and Sinou have reported the synthesis of chiral bisoxazolines, which also proved to be active ligands in the asymmetric allylic alkylation of l,3-diphenylprop-2-enyl acetate, as well as cyclopropanation, allylic oxidations and Diels-Alder reactions. [62] The ligands do not have a fluorine content greater than 60 wt% and so are not entirely preferentially soluble in fluorous solvents, which may lead to a significant ligand loss in the reaction system and in fact, all recycling attempts were unsuccessful. However, the catalytic results achieved were comparable with those obtained with their non-fluorous analogues. 

In another example of catalysis by the hydrogen-bonded hexamers, Shimizu et al. prepared Teflon-footed resorcin[4]arenes [56] (i.e., resorcin[4]arenes with per-fluorinated side chains) that form hexameric capsules in wet fluorous solvents. These capsules, several years later, were used to accelerate a Diels-Alder reaction in abiphasic system [56b]. 

Lanthanoid salts with non-coordinating anions carrying long perfluoroalkyl chains, Yb[C(SO2CgFi7)3[3 (19) and Sc[C(SO2CgFi7)3[3 (20), have been successfully used as Lewis catalysts for O-acylations, Friedel-Crafts, Diels-Alder, and Mu-kayama aldol reactions in fluorous biphasic media [21] (Scheme 3.6). In these reactions the fluorous medium avoids deactivation of the Lewis acid by solvent coordination. The catalyst can also be recycled and reused. 

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