Are carboxylic esters really refractory to DAST? On the fluorination of α-hydroxyesters with DAST

A Convenient Synthesis of Difluoroalkyl Ethers from Thionoesters Using Silver(I) Fluoride

“…Prominent among these approaches is fluorodesulfurization using highly reactive fluorinating agents including SF 4 gas or BrF 3 (Type I), or combinations of oxidizing agents with hydrofluoric acid (Type II) . Alternatively, both DAST and DeoxoFluor (Type III) have demonstrated utility in the deoxyfluorination or fluorodesulfurization of esters or thionoesters, respectively. As a strategic alternative, the rearrangement of heteroaryl ketones using XeF 2 and HF/pyr or displacement of bromide from α,α‐difluoro‐α‐bromo esters and amides (e.g., 7 → 11 ) are also employed for the synthesis of difluoroalkyl ethers (e.g., 4 ) and heterobenzylic difluoro ethers (e.g., 5 ) .…”

“…Prominent among these approachesi sf luorodesulfurization [9] using highly reactive fluorinating agents including SF 4 gas [9b] or BrF 3 [9c] (Type I), or combinations of oxidizinga gents with hydrofluorica cid (Type II). [1b, 9a, 10] Alternatively, both DAST and DeoxoFluor( Type III) [11] have demonstrated utility in the deoxyfluorination or fluorodesulfurization of esters [12] or thionoesters, [12][13] respectively.A sastrategic alternative, the rearrangement of heteroaryl ketones using XeF 2 and HF/pyr [5b] or displacemento fb romide from a,a-difluoro-a-bromo esters [14] and amides [15] (e.g., 7!11)a re also employed for the synthesis of difluoroalkyl ethers (e.g., 4) [6] and heterobenzylic difluoro ethers (e.g., 5). [7] Unfortunately,m any of the reagents relevant to the synthesis of difluoroalkyl ethers are toxic, dangeroust o handle, and react violently with water.O wing to this extreme reactivity,u se of theser eagents is often limited to substrates devoid of unprotected functional groupsa nd under strictly anhydrous reaction conditions.…”

Monofluorination of Organic Compounds: 10 Years of Innovation

“…Deoxofluorination of α-Hydroxy-β-diesters. Ruzziconi and co-workers described the deoxofluorination of α-hydroxy-β-diesters using DAST (Scheme ) . The reaction worked well on α-methyl malonates but the use of larger substituents gave a mixture of polyfluorinated products.…”

“…Ruzziconi and co-workers described the deoxofluorination of αhydroxy-β-diesters using DAST (Scheme 110). 175 The reaction worked well on α-methyl malonates but the use of larger substituents gave a mixture of polyfluorinated products. The authors reported that the reaction is very sensitive to steric and electronic effects.…”

Synthesis of new indole-based bisphosphonates and evaluation of their chelating ability in PE/CA-PJ15 cells

“…As previously reported, 3-methyleneindolines are valuable building blocks for 3-functionalized indole derivatives due to the remarkable reactivity of the exocyclic carbonecarbon double bond through the "ene" reaction [34,35]. These findings led us to consider their use for the synthesis of new regioselectively substituted tetraethyl [3-(1H-indol-3-yl)propane-1,1-diyl] bis(phosphonate) derivatives 1aef with Ca 2þ chelating ability and improved cell permeability (Fig.…”