Dinucleotides containing two allyl groups by combinations of allyl phosphotriesters, 5-allyl-, 2′-O-allyl- and 2′-arabino-O-allyl uridine derivatives as substrates for ring-closing metathesis

Five different dinucleotides, each containing two allyl groups in various positions, were prepared and studied as substrates for ring-closing metathesis reactions. These dinucleotides were designed from appropriate nucleoside building blocks combining four different positions for the allyl group; the allyl phosphotriester linkage, 5-allyl-2′-deoxyuridine, and ribo- as well as arabino-configured 2′-O-allyluridine. Thus, convenient procedures for these building blocks were developed. From the dinucleotides, two new cyclic nucleotide structures were obtained; one connecting two adjacent nucleobase moieties and the other forming an unsaturated four-carbon linkage between the phosphate moiety and the adjacent pyrimidine nucleobase. The latter cyclic dinucleotide was also prepared with a saturated four-carbon linkage using a tandem ring-closing metathesis-hydrogenation procedure. This compound was found to be significantly more stable towards a nucleophilic ring-opening than its unsaturated counterpart.