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A cyclic pseudopeptide containing the RGD sequence has been synthesized in high yield by ring-closing metathesis using a Grubbs’ catalyst in tetrahydrofuran. Conformational analysis has been correlated to structure modeling and preliminary biological activity as an integrin binding inhibitor has been evaluated.

Ring closing metathesis has been performed for the first time on a soluble poly(ethylene glycol) supported substrate in the presence of Grubbs' catalyst and provided in good yields 6-, 7- and 8-membered ring aminoacid derivatives. The presence of the polymer required the use of a higher amount of ruthenium complex but the addition of a cofactor such as 1-octene improved the turnover of the catalyst. On the other hand, a Schiff base protected glycine supported on a poly(ethylene glycol) reacted readily with various electrophiles in the presence of an inorganic base under microwave activation.

A new soluble poly(ethylene glycol)-supported protecting group of the SES (silylethylsulfonyl) type has been prepared and utilized in the synthesis of cyclic amino esters by ring-closing metathesis (RCM). Acidic cleavage from the support was performed to recover the fully deprotected amino acids. More conventional deprotection conditions with fluoride anions resulted in aromatization of the heterocycles in the case of the 6-membered ring and provided a new route to the synthesis of substituted pyridines. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).