ChemInform Abstract: Enantioselective Introduction of Fluoride into Organic Compounds. First Asymmetric Ring Opening of Epoxides by Hydrofluorinating Reagents.

Abstract

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Cobalt-Catalyzed Trifluoromethoxylation of Epoxides

“…Nucleophilic ring-opening of epoxides represents an important method to obtain, in single step, bifunctional organic molecules. − Accordingly, various nucleophiles have been reported in the past few years, such as amines, thiols, hydroxyl, − phenol, , carboxylic acids, − azide, , cyanide, − halogen − and so on. In comparison, the trifluoromethoxy group (OCF 3 ) is rarely used as the nucleophile in the ring-opening reaction of epoxides, even though OCF 3 -containing compounds are of great interest in new drug and agrochemical design due to its unique properties. − It would be the poor nucleophilicity and unstability of trifluoromethoxy anion limited its application in this area.…”

Asymmetric Ring-Opening of Epoxides Catalyzed by Metal–Salen Complexes

“…Attempts to lower the catalyst loading resulted in a drastic drop in enantioselectivity. The reaction also produced some amount of the corresponding chlorohydrin [75]. Changing the fluoride source to silver fluoride led to improved yields and enantioselectivities, and complete suppression of the formation of the chlorinated by-product, although a high catalyst loading of 50-100 mol% was still required (Scheme 18) [76].…”

“…Haufe and coworker investigated Cr-salen complex 46 (Scheme 18) as catalyst for the enantioselective fluorination of epoxides [75][76][77]. The studies included a limited number of examples of the KR of terminal epoxides.…”

Catalytic asymmetric nucleophilic fluorination using BF3·Et2O as fluorine source and activating reagent

“…Alternatively, nucleophilic fluorine reagents (F − reagents) have been attracting considerable interest recently since the relative stability and low-cost. Considerable advances have recently been achieved in this field involving catalytic asymmetric fluorination of keto esters 19,20 and alkenes [21][22][23][24][25] employing pyridine•HF as a fluorine reagent, catalytic asymmetric fluorination of allylic trichloroacetimidates using a combination of Et 3 N•HF with Iridium complex 26 , asymmetric ring-opening fluorinations of mesoepoxides (aziranes) using PhCOF, HF-reagents or AgF as the fluorine source in metal-catalyzed system [27][28][29] , and other asymmetric transformations in the presence of metal fluorides (KF, CsF or AgF) [30][31][32] (Fig. 1b).…”