Traceless Linkers Based on Olefin Metathesis

Recently, it was shown that bis(tricyclohexylphosphine)benzyhdene ruthenium dichloride (101) [120, 121] is also capable of catalyzing olefin metathesis on a sohd support [122], Thus, performing the reaction as ring-closing metathesis offers an- 

Other possibility for a traceless release of combinatorial compounds from solid supports. As only the desired products are cleaved during fhe reaction, these are obtained in high purity. The method is compatible wifh a whole variety of different functionalities, such as carboxylic acids, carboxylic acid anhydrides, amides, aldehydes, ketones, alcohols, and sulfonamides. 

The first step consisted of the Mitsunobu etherification of an allyl alcohol with the resorcinol monoester, which afforded 102. Cleavage of the benzoyl protecting group released the phenol, which was then attached to the solid support. One-step cleavage of the THP group and bromination was achieved with PPhs/C Br4 to furnish 103. Nucleophilic substitution of the bromide with benzylamine was followed by acylation of the secondary amine wtith N-Boc-allylglycine 104, which resulted in the precursor 105, ready for the metathesis reaction this was performed with catalyst 101 to yield the final product 106. Either 1-octene or ethene was employed to generate 101. 

Using the same type of linker, the authors have also synthesized heterocyclic six- 

The analogous strategy starting from 107, involving metathesis of a,(B-dienes 

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