PhSCF2SiMe3 () underwent fluoride-catalyzed nucleophilic addition to the carbonyl group of anhydrides to provide the corresponding γ-difluoro(phenylsulfanyl)methyl γ-lactols, which were employed for the synthesis of γ-difluoromethylated γ-lactams.
Fluoride-catalyzed stereoselective nucleophilic addition of PhSCF(2)SiMe(3) (1) to α-carboethoxycycloalkanones 2 followed by intramolecular radical cyclization of the resulting cis-3 adduct afforded the corresponding gem-difluoromethylenated bicyclic compounds 4, which underwent ring-expansion followed by the Baeyer-Villiger-type oxidation of the resulting macrocyclic ketone intermediates to give gem-difluoromethylenated macrocyclic lactones 5.
Direct nucleophilic gem-difluoro(phenylsulfanyl)methylation of carbonyl compounds has been achieved by use of difluoro(phenylsulfanyl)methane (PhSCF 2 H) and the phosphazene base P 4 -tBu in THF. Non-enolizable aldehydes and ketones are suitable substrates to undergo nucleophilic
An efficient C1-difluoromethylation of tetrahydroisoquinolenes was achieved using TMSCFSPh as a difluoromethylating agent and 2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (TEMPOBF) as an oxidant. The process provides an access to a variety of C1-difluoro(phenylsulfanyl)methylated tetrahydroisoquinoline adducts in good yields. These adducts were employed as key precursors for preparing fluorinated pyrrolo[2,1-a]isoquinoline and benzo[a]quinolizidines.
Stereoselective synthesis of 1-fluoro-exo,exo-2,6-diaryl-3,7-dioxabicyclo[3.3.0]octanes is described. The synthetic strategy involves stereoselective fluorination of 3,4-trans-4,5-cis-3-aroyl-5-arylparaconic esters using Selectfluor to afford the corresponding fluorinated paraconic esters in good yields as a single isomer, which are subjected to reduction employing LiAlH4 or DIBALH followed by furofuran formation under acidic or Lewis acid conditions to afford a series of 1-fluoro-exo,exo-furofurans in moderate yields. The synthetic protocol also provides an access to (±)-1-fluoromembrine.
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