Lewis acids catalyzed ring-opening reactions of methylenecyclopropanes and epoxides in supercritical carbon dioxide or modified supercritical carbon dioxide with perfluorocarbon

Lithium Bromide, an Inexpensive and Efficient Catalyst for Opening of Epoxide Rings by Amines at Room Temperature under Solvent‐Free Condition

“…This led to the necessary use of catalysts to activate the epoxide ring for nucleophilic cleavage. Therefore, continuous efforts have been made to develop various catalysts such as alumina,6 metal amides and triflamide,7 alkali metal perchlorates and tetrafluoroborate,8 metal triflates,9 metal alkoxides,10 zirconium sulfophenyl phosphonate,11 metal halides,12 silica gel under high pressure,13 montmorillonite K 10 under microwave irradiation,14 hexafluoro‐2‐propanol (HFIP) under reflux,15 ionic liquids,16 n Bu 3 P,17 Yb(OTf) 3 in supercritical CO 2 under high pressure at 55 °C,18 and silica gel 19. However, some of these methodologies require long reaction times, elevated temperatures, high pressure, air‐ and moisture‐sensitive catalysts, stoichiometric amounts of costly catalysts, special apparatus etc.…”

An efficient synthesis of 2-amino alcohols by silica gel catalysed opening of epoxide rings by amines

“…These include the use of alumina, 6 metal amides and triflamide, 7 alkali metal perchlorates and tetrafluoroborate, 8 metal triflates, 9 metal alkoxides, 10 zirconium sulfophenyl phosphonate, 11 metal halides, 12 microwave irradiation, 13 hexafluoro-2-propanol (HFIP) under reflux, 14 ionic liquid, 15 n Bu 3 P, 16 and Yb(OTf ) 3 in supercritical CO 2 under high pressure at 55 ЊC. 17 However, these methodologies suffer from one or more disadvantages such as long reaction times, elevated temperatures, high pressure, moderate yields and regioselectivities, use of air and moisture sensitive catalysts, use of halogenated solvents, requirement of stoichiometric amounts of catalyst, use of costly reagents/catalysts, the need to use special apparatus, rearrangement to allylic alcohols, 18 potential hazards in handling pyrophoric/moisture sensitive reagents in the preparation of the catalyst, and in most of the cases being applicable to aromatic amines only. Therefore, the development of a better catalyst is in high demand.…”

Recent developments in the reactivity of methylene- and alkylidenecyclopropane derivatives

“…12 As shown in Scheme 2, the reaction led to a mixture of the corresponding mono-and dialkylated amine products in good yields. In some cases, the dialkylated compound was obtained as the single product in high yield.…”

“…12 In contrast with the reactions with amines as nucleophiles performed under similar conditions, these reactions with alcohols proceeded very well without any perfluorocarbon additive, because the alcohol itself could modify scCO 2 fluid to solvate the Lewis acid.…”