Triflone

Triflones reacted with p-tolylsulfonyl azide in the presence of two equivalents of base (NaH/glyme) and afforded vinyl azides380. These azides were reduced with LiAlH4 to afford the corresponding amines and, upon treatment with triethyl phosphite, they gave ketones after hydrolysis381. 

The cyclopropane cyclizations by elimination of triflinic acid (CF3S02H) are readily effected by basic treatment of triflones (trifluoromethyl alkyl sulfones) with activated /-protons (equations 46 and 47)39. The cyclopropane diesters 45 are formed on treatment of 44 with potassium hydride in DMSO or sodium methoxide in methanol (equation 48). In contrast, the monoester 46 failed to give the desired cyclopropane40. Addition of carbanions derived from /f, y-unsaturated phenyl sulfones to a, /i-unsaturated carboxylic esters and subsequent elimination of benzenesulfinate ion give cyclopropanes possessing the unsaturated side chain and the ester function in trans positions (equation 49)41. 

Triflate anions, elimination of 639 Triflinates, rearrangement of 669 Triflones 669... 

Vinyl triflones 636 Vitamins, synthesis of 833 VSEPR theory 34... 

There have been Ramberg-Backlund-type reactions in which the leaving group is not a halide ion. For example, treatment of the polyalkylated methyl triflone 365 is known to result in a Ramberg-Backlund reaction forming the corresponding olefin. Since methyl triflone 364 can be alkylated successively regiospecifically at the two carbon atoms, Hendrickson and coworkers used this reaction for the synthesis of some tailor-made olefins. 

It has also been reported" " that rearrangements of both a- and y-propylallyl triflinates on heating in acetonitrile yield the same sulfone y-propylallyl triflone. Although the possibility of an ion-pair mechanism may be responsible for the lack of allylic rearrangement in one case as a result of the better leaving group ability of the triflinate anion as compared with the arenesulfmate anion, it is just as likely a consequence of the unbuffered conditions in which these reactions were performed. In this respect this is reminiscent of the results observed by Cope and coworkers" mentioned above which were also performed under nonbuffered conditions, and which could be simply corrected by the addition of 2,6-lutidine . 

The ability to conduct radical reactions without the use of tin reagents is important. Allylic triflones have been used to conduct allylation reactions on a range of substrates (39) as a replacement for allyltributylstannane (Scheme 28). The main limitation was that unactivated or trisubstituted triflones failed to undergo reactions. In other nontin radical methods, arenesulfonyl halides have been used as functional initiators in the CuCl/4,4 -dinonyl-2, 2 -bipyridine-catalysed living atom-transfer polymerization of styrenes, methacrylates, and acrylates.The kinetics of initiation and propagation were examined with a range of substituted arylsulfonyl halides with initiator efficiency measured at 100%. 

Heteroaromatic naphthalene derivatives generally have a lower HOMO-LUMO gap than the analogous phenylene-based compounds, leading to a bathochromic shift of the PL emission maxima. By superimposing the PL spectra of 364 (X = 469 nm/498 nm) and the corresponding triflone 365 (X = 485 nm), it can be shown that replacement of cyano by triflyl does not shift the spectral position of the nathylenevinylenes. 

The radical C-H transformation of ethers is generally initiated by a-hydrogen abstraction with highly reactive radicals generated from such initiators as peroxides [3a, g], photo-activated carbonyl compounds [3b—d], metallic reagents [3i, j], and redox systems [3f, h[. Various combinations of ethers, radical initiators, and radical acceptors (e.g. carbon-carbon multiple bonds) may be used as the reaction components [6], Several notable means of direct C-C bond formation via the radical a-C-H transformation of ethers involve the use of triflon derivatives [7], the phthalimide-N-oxyl (PINO) radical [8], 2-chloroethylsulfonyl oxime ethers [9], and N-acyl aldohydrazones [10],... 

Primary and secondary trifluoromethylsulfones (triflones) such as 12 are efficiently obtained from readily available sodium trifluoromethanesulfinate (10) and alkyl bromides (e. g., 11) in A, A -dimethylacetamide (DMAC). Simple primary alkyl bromides may also be employed. 

Allyl halides also react well with sulfinates and give good yields in this reaction under comparable conditions to those employed for the triflones." "... 

Xiang et al. added Bu SnH to an alkynyl triflone [176] in the presence of Pd(PPh3)4. Casson and Kocienski obtained a-alkoxyalkenyltins by addition of Bu3SnH to the corresponding alkynyl ethers [199]. 

Even unactivated hydrocarbons can be alkynylated to furnish disubstituted alkynes. For example, treatment of cyclohexane with the acetylenic triflone (RC=C-S02CF3)... 

The alkylation of sulfones has played an important role in this development. Most of this work has been performed with aryl sulfones, and in only rare cases have triflones (RS02CF3) or dialkyl sulfones been employed. ... 

Simple sulfonyl carbanions which do not contain additional carbanion-stabilising groups, e.g. carbonyl groups or heteroatoms, can be readily alkylated in high yield by modern techniques with the use of alkyllithiums and lithium amide bases. A number of allylic halides have been successfully used. In allylic halides, the halogen directly attached to the double-bonded carbon is relatively inert towards nucleophilic attack (Scheme 41). In this way, sulfones (96) can be transformed via desulfonation into vinyl halides (97) or into ketones (98) by hydrolysis (Scheme 41). In contrast to ordinary alkyl sulfones, triflones (99) can be alkylated under mildly basic conditions (potassium carbonate in boiling acetonitrile) (Scheme 42). The ease of carbanion formation from triflones (99) arises from the additional electron-withdrawing (-1) effect of the trifluoromethyl moiety. 

Ethynytation. On photoactivation in the presence of hexabutylditin the reaction of the triflone with various alkyl iodides leads to the silylated alkynes. To minimize polymerization of the reagent reactions are conducted at low concentration. 

The ability to conduct radical reactions without the use of tin reagents is important. Allylic triflones have been used to conduct allylation reactions on a range of substrates... 

Another approach to carrying out tin-free radical fragmentation processes, developed by Fuchs, utilizes trifluoromethyl sulfone, or triflone, derivatives. Fuchs first reported examples of free radical alkynylation reactions using acetylenic triflone 102 [62]. What is most remarkable about these reactions is that the radicals being alkynylated are formed from the cleavage of C-H bonds standard radical precursors are not required. For example, when tetrahydrofuran is mixed with triflone 102 at room temperature, alkynylation occurs a to the ether oxygen in 92% yield (Scheme 21). In this case, the radical chain process is most likely initiated by traces of peroxides in the THF. Similarly, unactivated alkanes such as cyclohexane will react with triflone 102 in good yield (83% for cyclohexane) when heated with a catalytic amount of AIBN. 

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