Diastereoselectivity in the osmium-catalyzed dihydroxylation of allylic amides and carbamates was written by Krysan, Damian J.;Rockway, Todd W.;Haight, Anthony R.. And the article was included in Tetrahedron: Asymmetry in 1994.Reference of 28322-40-9 This article mentions the following:
The stereochem. of the osmium-catalyzed dihydroxylation of chiral allylic amides and carbamates I (R = BOC, PhCH2O2C, EtO2C, Ac, Cl3CO, i-BuCO, R1 = R2 = H, R3 = i-Bu; R = BOC, R1 = R3 = H, R2 = i-Bu; R1-R3 = H, R1 = Me, R2 = R3 = H) has been studied. The diastereoselectivity depended on the solvent, the N protecting group, and the geometry and substitution pattern of the olefin substrate. In contrast to the erythro selectivity observed with allylic alcs., osmylations of I were threo selective to give threo-II (same R-R3) . Stoichiometric osmylations were consistently more selective than the corresponding catalytic reactions. Control experiments suggest this is due to the presence of a second catalytic cycle based upon an osmium glycolate catalyst which accumulates as the reaction proceeds to completion. Double diastereoselective dihydroxylations of allylic carbamates were also briefly examined In the experiment, the researchers used many compounds, for example, Isopentyltriphenylphosphonium bromide (cas: 28322-40-9Reference of 28322-40-9).
Isopentyltriphenylphosphonium bromide (cas: 28322-40-9) belongs to organobromine compounds. Most of the natural organobromine compounds are produced by marine organisms, and several brominated metabolites with antibacterial, antitumor, antiviral, and antifungal activity have been isolated from seaweed, sponges, corals, molluscs, and others. Commercially available organobromine pharmaceuticals include the vasodilator nicergoline, the sedative brotizolam, the anticancer agent pipobroman, and the antiseptic merbromin. Reference of 28322-40-9
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary