Enantiospecific deoxyfluorination of cyclic α-OH-β-ketoesters

Abstract

Cyclic α-hydroxy-β-ketoesters were converted in the corresponding α-F-derivatives with high levels of enantiospecificity using DAST under operationally simple conditions.

Diethylaminosulfur Trifluoride: A Novel, Low-Cost, Stable Double Thiolation Reagent for Imidazo[1,2-α]pyridines

“…Based on these preliminary mechanistic studies and relevant reports, − we proposed a reaction mechanism, as depicted in Scheme . Initially, 2-arylimidazo­[1,2-α]­pyridines ( 1a ) could exist as the resonance structure A , which reacts with DAST to furnish intermediate B with the elimination of HF.…”

“…Diethylaminosulfur trifluoride (DAST), as commercially available organic synthons, has usually been utilized as a fluorinated reagent and trifluoromethylthiolation reagent. [41][42][43][44][45][46]50,51 Based on our research interest in the C−H bond functionalization strategies to manipulate various imidazopyridines, 47,48 we herein report a metal-free, nucleophilic strategy for the synthesis of bis(imidazo [1,2- DAST efficiently to afford the desired products 3b−3d in good yields. Meanwhile, the presence of an electron-donating substituent like the methyl, methoxy, or phenyl group was able to give products 3e−3g in up to 92% isolated yield.…”

“…Diethylaminosulfur trifluoride (DAST), as commercially available organic synthons, has usually been utilized as a fluorinated reagent and trifluoromethylthiolation reagent. − ,, Based on our research interest in the C–H bond functionalization strategies to manipulate various imidazopyridines, , we herein report a metal-free, nucleophilic strategy for the synthesis of bis­(imidazo­[1,2-α]­pyridine-3-yl)­sulfanes using DAST as a sulfur source, which shows good scope and functional group tolerance (Scheme d). Moreover, our aim was to explore new chemical transformation of DAST and ascertain its use as a novel sulfur reagent.…”