Selective introduction of a fluorine atom into carbohydrates and a nucleoside by ring-opening fluorination reaction of epoxides

Abstract

Ring-opening fluorination reactions of epoxides using tetrabutylammonium bifluoride (TBABF)-KHF 2 , or Et 3 N-3HF under microwave irradiation were applied for the introduction of a fluorine atom into the carbohydrate molecules. When TBABF-KHF 2 was used as the fluorination reagent, a fluorine atom was introduced regioselectively and various functional groups can tolerate the conditions. When Et 3 N-3HF was used under microwave irradiation, the reaction time could be remarkably shortened compared with the conventional oil-bath heating.

Monofluorination of Organic Compounds: 10 Years of Innovation

“…Racemic Reactions. Hara and co-workers described the fluorination of carbohydrates by opening of epoxides under neat conditions . Either TBABF-KHF 2 with thermal activation or Et 3 N·3HF under microwave irradiation can be used.…”

“…Hara and co-workers described the fluorination of carbohydrates by opening of epoxides under neat conditions. 305 Either TBABF-KHF 2 with thermal activation or Et 3 N•3HF under microwave irradiation can be used. The former required longer reaction times, but similar yields are obtained in both cases.…”

Site-Selective Photochemical Fluorination of Ketals: Unanticipated Outcomes in Selectivity and Stability

“…These are the most commonly encountered type of fluorinated sugars in the literature due to the well-established reactivity at the anomeric position. Other positions have also been fluorinated utilizing the same nucleophilic and electrophilic sources of fluorine; however, they typically require specialized precursors and/or longer syntheses . Only a few C–H functionalization methods are known to produce gem -oxyfluorides directly from their corresponding ethers, esters, or other oxygen-containing substrates.…”

Synthetic strategies for fluorination of carbohydrates

“…Hara and colleagues [49] have studied the fluorination of epoxides leading to 6-fluoro-furanoses employing Et3N-3HF mixtures by microwave irradiation, resulting in a considerable shortening of reaction times and improvement in yields, according to Scheme 26.…”