Carl L. Bumgardner

Synthesis of fluorinated heterocycles

Selected 1,3-diketones having a trifluoromethyl group and/or a fluorine in the 2-position were condensed with aromatic hydrazines, hydroxylamine, urea, thiourea, guanidine, and substituted anilines producing pyrazoles, isoxazoles, pyrimidines, and quinolines, respectively, in yields ranging from 27 to 87%.

Preparation of α-fluoroaldehydes and α-fluoroketones using dilute fluorine

Abstract Fluorination of silyl enol ethers with 5% F 2 in N 2 at −78°C in Freon 11 results in the formation of α-fluoroketones and α-fluoroaldehydes.

Lack of polymerization of fluorinated acrylates

Abstract trans -Ethyl 3-fluoroacrylate and ethyl 2-methyl-3,3-difluoroacrylate do not undergo radical initiated polymerization. They form 1:1 adducts with α-alkoxy radicals in high yield.

Aryl trifluoromethyl acetylenes

Abstract A wide variety of aryl trifluoromethyl acetylenes may be prepared in high yield by allowing CF3CCZnCl, generated from CF3CCH, to react with aryl iodides a catalytic amount of tetrakis(triphenylphosphine)-palladium.

Ring-fluorinated pyrazoles

Abstract 2-Fluoro-1,3-diketones react with phenylhydrazine to yield ring-fluorinated pyrazoles in high yield. An isoxazole is produced when 2-fluoro-1,3-diphenyl- 1,3-propandione is treated with hydroxylamine hydrochloride.

On the role of the CF3 group in determining the relative stability of E, Z-isomers

Although base-catalyzed addition of PhSH to PhCCCF, under thermodynamic control gives E-Ph(PhS)CCH(CF3), Z-Ph(PhO)CCH(CF3) is the thermodynamically favored product from similar reaction of PhOH with PhCCCF3. The preference for the cis-configuration of CF3 and PhO on a double bond is rationalized in terms of frontier orbital interactions.

Radical additions to β,β-difluoroacrylates

Abstract Tetrahydrofuran, 1,3-dioxolane, hexanal, and benzaldehyde react readily with β,β-difluoroacrylates under free radical conditions to furnish adducts in moderate to high yield.

Preparation of esters containing an β-CF3 group

Abstract Malonates may be converted to esters containing an δ-CF3 group in a two-step process involving bromodifluoromethylation of the malonates followed by decarboxyalkylation-fluorination with fluoride ion in DMSO.

Preparation and synthetic utility of cyclopropyl phenyl sulfides

Abstract Primary alkyl halides and epoxides react with 1-lithiocyclopropyl phenyl sulfide to give derivatives suitable for transformation to carbonyl compounds or for desulfurization.

Synthesis of β,β-difluoroacrylates

Abstract Diethyl malonates substituted in the α-position by an alkyl group may be bromo- difluoromethylated to give derivatives suitable for conversion to β,β-difluoro-α-alkylacrylates. The final step involves dealkoxycarbonylation-elimination promoted by potassium bromide in dimethyl sulfoxide.