Michael H. Rock

Addition of organolithium reagents to α-(trifluoromethyl)styrene: concise synthesis of functionalised gem-difluoroalkenes

The treatment of α-(trifluoromethyl)styrene with organolithium reagents results in the selective formation of gem-difluoroalkenes in good-to-excellent yields. This reaction has been applied to the synthesis of 3-gem-difluoro-2-phenylallylic amines and other functionalised gem-difluoroalkenes.

A concise synthesis of functionalised gem-difluoroalkenes, via the addition of organolithium reagents to α-trifluoromethylstyrene

The treatment of α-trifluoromethyl styrene with organolithium reagents results in the selective formation of gem-difluoroalkenes in good to excellent yield. This reaction has been applied to the synthesis of a range functionalised gem-difluoroalkenes.

Synthesis of 3-gem-difluoro-2-ethoxy allylic alcohols from ethyl chlorodifluoroacetate

Abstract The chlorine atom in chlorodifluoromethyl epoxy ethers is unusually reactive towards butyllithium. This reactivity has been used to develop a concise synthesis of gem-difluoro2-ethoxy allylic alcohols from the commercially available ethylchlorodifluoroacetate.

Highly selective 1,3-dipolar cycloaddition of a cyclic azomethine ylide to ethyltrifluorocrotonates

Abstract The 1,3-dipolar cycloadditions of ethyltrifluorocrotonates to the azomethineylide, generated from 2-( tert -butyl)-3-methyl-imidazolin-4-one and formaldehyde, proceeds with a high degree of stereo- and regioselectivity to give precursors of 4-trifluoromethylpyrrolidine-2,3-dicarboxylic acids in good yields.

ELECTROSYNTHESIS OF NEW FUNCTIONALIZED DIFLUORO ALLYLSILANES

Abstract An efficient electrochemical silylation of chlorodifluoromethyl enol ethers 2 afforded in good yields the new functionalized difluoromethyl allylsilanes 1 on a preparative scale. These silanes reacted as difluoromethyl anion equivalents with an aldehyde as electrophile, providing functionalized α-difluoromethyl alcohols 4 .

Z-TRIFLUOROMETHYL THIOENOL ETHERS, ENOL ETHERS, AND ENAMINES ; REACTIVITY TOWARDS ORGANOLITHIUM REAGENTS

Abstract Trifluoromethyl enol ethers and thioenol ethers conjugated with an unsaturation in the β-position undergo addition/elimination reactions with organolithium reagents to yield the corresponding trifluoromethyl alkenes while preserving the geometry of the double bond. Trifluoromethyl enamines exhibit a different reactivity towards organolithium reagents with a vinyl anion being formed in preference to addition/elimination products.

Halogenation of 1-trifluoromethyl enamines: A new and efficient synthesis of α-bromo- and α-iodo-trifluoromethyl ketones

Abstract Treatment of the 1-trifiuoromethyl enamines 1a-d with bromine or iodine results in the formation of the corresponding iminium salts. Treatment of any of these salts with methanol results in the formation of the corresponding α-halo-trifluoromethyl ketones.

Concise stereoselective synthesis of 1-perfluoroalkyl enamines via the addition of N-lithiated amines to enol ethers and their subsequent metalation to form new functionalized enamines

Addition of lithium amides derived from a range of cyclic, sterically demanding, and chiral amines, to trifluoromethyl (Z)-enol ethers 1 and 4, provides stereoselectively the corresponding (Z)-enamines 3a–e and 7 in good yields. This reaction has been extended to the perfluoroalkyl and chlorofluoroalkyl enol ethers (CF2Cl, C2F5). The enamines can react with ButLi to give vinylic anions and, after quenching with aldehydes and ethyl chloroformate, provide new functionalized enamines 12–16.

Conversion of trifluoromethyl carbonyl compounds to the corresponding vinylsilanes with cyclopentadienyltris(trimethylsilylmethyl) titanium(IV)

Abstract The conversion of trifluoromethyl ketones, esters, amides, and thioesters to their corresponding vinylsilanes using cyclopentadinyl tris (trimethylsilylmethyl)titanium(IV) has been investigated.

The mass spectrometric behaviour of some halogen-containing epoxyethers

The mass spectrometric behaviour of 1,2-epoxy-1-phenyl-2-ethoxy-3,3,3-trifluoropropane (1), 1,2-epoxy-1-phenyl-2-ethoxy-3,3-difluoro-3-chloropropane (2) and 2,3-epoxy-1-cyclohexyl-3-ethoxy-4,4,4-trifluorobutane (3) has been studied by means of electron impact and fast atom bombardment experiments. The decomposition pathways of odd electron molecular ions and protonated molecules have been studied by means of metastable ion spectra. Specific fragmentation channels are present for the three compounds; while for all the compounds C2H5O• loss is highly favoured for 2 the ethyl radical loss becomes predominant. This has been justified by formation of a chloronium cation. Compound 3 only exhibits a product ion related to cleavage of the oxirane ring, suggesting that the lack of conjugation leads to labilisation of the oxirane ring. The protonated molecules partially decompose according to the structure of the alkoxycarbenium ion already proposed in the condensed phase. In the case of 1 the hydroxyl localisation on C(2) has also been evidenced.