Fluorous carbodiimide

Fluorous-tagged reagents are very attractive for reactions in which a stoichiometric by-product is formed that is difficult to separate. An example is perfluor-oalkylated triphenylphosphane for use in Wittig and aza-Wittig reactions, where the corresponding phosphane oxide is removed by fluorous extraction [22, 23]. Similarly, fluorous sulfoxide has been employed in Swern oxidations, and fluorous carbodiimide has been used as a coupling reagent [24, 25]. 

Fluorous carbodiimide was used for dipeptide and ester synthesis. The reaction was carried out in CH2CI2 and FC-72, and the fluorous urea byproduct was extracted in the FC-72 using perfluoroheptanoic acid. The acid formed a stable complex with the fluorous urea and the solubility of the complex in FC-72 was dramatically increased compared with the fluorous urea. 

Proline analogs, biaryl-substituted, fluorous synthesis 112 PS-anthracene, dienophiles 151 PS-carbodiimide 136 Pimine C-2, nucleophilic displacement 119... 

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