The 5'-alkynylation of uridine-derived aldehydes is described. The addition of alkynyl Grignard reagents on the carbonyl group is significantly influenced by the 2',3'-di-O-protecting groups (R1): O-alkyl groups led to modest diastereoselectivities (65:35) in favor of the 5'R-isomer, whereas O-silyl groups promoted higher diastereoselectivities (up to 99:1) in favor of the 5'S-isomer. A study related to this protecting group effect on the diastereoselectivity is reported.
Othman, R. B., Fer, M. J., Le Corre, L., Calvet-Vitale, S., & Gravier-Pelletier, C. (2017). Effect of uridine protecting groups on the diastereoselectivity of uridine-derived aldehyde 5’-alkynylation. Beilstein Journal of Organic Chemistry, 13, 1533–1541. https://doi.org/10.3762/bjoc.13.153