Influence of resin cross-linking on solid-phase chemistry

A range of PS-DVB resins were prepared by suspension polymerization with st yrene, p-chloromethyl styrene, and DVB. Yields of polymerization increased (from 40% to almost 80%) with increasing cross-linking. The beads exhibited the expected swelling characteristics, with the 0.3% resin swelling to alm ost 9 times its dry volume in CHCl3, Kinetics of cleavage of the dye Methyl Red from the range of Rink linked resins showed rate enhancements of up to 500% between the 6.0 and the 0.3% cross-linked resins. Total synthesis of Kawaguchipeptin B was carried out on the resins, and their performance duri ng the syntheses was investigated. Contrary to expectations, the purities o f the cyclic peptide product increased with increasing resin cross-linking doubling from the 0.3-6.0% resin. A Suzuki reaction showed the half-lives o f reaction increased with increasing resin cross-linking with an Ii-fold in crease in half-life between the 0.3-2.7% resin, Surprisingly, we observed v ery little reaction in the case of the 3.0 and 6.0% cross-linked resins.