Fluoroalkyl esters

Fuchigami s group and Laurent s group independently found that electron-withdrawing groups, such as fluoroalkyl, ester, and cyano groups, markedly promote anodic ot-fluor-ination of sulfides, as in Eqs. (12) and (13) [42-46]. 

One such flare, described in some advertising literature, claims the use of fluoroalkyl-ester monomers as oxidizer and (after casting and curing) as binder. Heat of reaction is up to 2 kca)/g, and an auto-ignition temperature above 470" C has been reported. 

Recently, Dong and Sun disclosed an unprecedented intermolecular asymmetric a-aldol reaction of vinylogous NHC-enolates, a type of versatile but less explored species relative to simple NHC-enolates. In contrast to the known C—C bond formation at the y-position of vinylogous NHC-enolates, this reaction exhibits complete a-selectivity. Unlike most cycloaddition reactions of NHC-enolates with external carbonyl electrophiles, this reaction does not involve a cycloaddition step. Notably, two challengingstereocenters, one quaternary and the other labile tertiary (both allylic and a-carbonyl), are also established in an acyclic product with excellent stereocontrol. A range of highly enantioenriched p,y-unsaturated P -fluoroalkylated esters have been synthesized with high efficiency under mild conditions. These products can be easily transformed into other useful molecules, such as densely functionalized tetrahydrofurans (Scheme 7.90). 

The fluoroalkyl hypochlorites readily react with GO and SO2 to form the corresponding chloroformates and chlorosulfates in near quantitative yields (270). They add to olefins giving a-chloroethers (271). Borate esters are obtained by reaction of perfluoroalkyl hypochlorites with BGl (272). 

Uses. /-Butyl hypochlorite has been found useful in upgrading vegetable oils (273) and in the preparation of a-substituted acryflc acid esters (274) and esters of isoprene halohydrins (275). Numerous patents describe its use in cross-linking of polymers (qv) (276), in surface treatment of mbber (qv) (277), and in odor control of polymer latexes (278). It is used in the preparation of propylene oxide (qv) in high yield with Httle or no by-products (269,279). Fluoroalkyl hypochlorites are useful as insecticides, initiators for polymerizations, and bleaching and chlorinating agents (280). 

Various sources of fluoride ion have been investigated, of which highly nucleophilic tetraalkylammonium fluorides ate the most effective Thuf, fluoro alkyl halides and N (fluoroalkyl)amines are efficiently synthesized by treatment of the corresponding trifluoromethanesulfonic esters with tetrabutylammonium fluoride trihydrate in aprotic solvents [5fl] (equation 34) The displacement reactions proceed quantitatively at room temperature within seconds, but tail with hydrogen fluoride-pyridine and give reasonable yields only with hydrogen fluo ride-alkylamine reagents... 

E NSF is a useful reagent for the low temperature conversion of the (hydroxyalkyl)phosphonic esters (88 X=OH R=allyl, or aryl) and (89.) into the corresponding (fluoroalkyl) phosphonic... 

Deacylation of hydrophobic p-nitrophenyl alkanoates Hydroxamic acid and phenyl ester derivatives had alkyl or fluoroalkyl substituents. Rate effects depend on selectivity of binding of fluoro- and hydro-carbon derivatives Kunitake et ai, 1984... 

However, most asymmetric 1,3-dipolar cycloaddition reactions of nitrile oxides with alkenes are carried out without Lewis acids as catalysts using either chiral alkenes or chiral auxiliary compounds (with achiral alkenes). Diverse chiral alkenes are in use, such as camphor-derived chiral N-acryloylhydrazide (195), C2-symmetric l,3-diacryloyl-2,2-dimethyl-4,5-diphenylimidazolidine, chiral 3-acryloyl-2,2-dimethyl-4-phenyloxazolidine (196, 197), sugar-based ethenyl ethers (198), acrylic esters (199, 200), C-bonded vinyl-substituted sugar (201), chirally modified vinylboronic ester derived from D-( + )-mannitol (202), (l/ )-menthyl vinyl ether (203), chiral derivatives of vinylacetic acid (204), ( )-l-ethoxy-3-fluoroalkyl-3-hydroxy-4-(4-methylphenylsulfinyl)but-1 -enes (205), enantiopure Y-oxygenated-a,P-unsaturated phenyl sulfones (206), chiral (a-oxyallyl)silanes (207), and (S )-but-3-ene-1,2-diol derivatives (208). As a chiral auxiliary, diisopropyl (i ,i )-tartrate (209, 210) has been very popular. 

Jean-Pierre Begue, Daniele Bonnet-Delpon, and Andrei Kornilov 153 WITTIG OLEFINATION OF PER-FLUOROALKYL CARBOXYLIC ESTERS SYNTHESIS OF 1,1,1-TRIFLUORO-2-ETHOXY-5-PHENYLPENT-2-ENE AND 1 -PERFLUOROALKYL EPOXY ETHERS 1,1,1-TRIFLUORO-2-ETHOXY-2,3-EPOXY-5-PHENYLPENTANE... 

The use of trialkyl phosphates for dialkylation of anilines has been found applicable to naphthylamines and to a large number of anilines substituted in the ortho, meta, or para position by groups such as chloro, methoxy, and methyl and in the meta position by fluoroalkyl (author s laboratory). The reaction has been used to introduce ethyl and M-butyl as well as methyl groups by employing the appropriate phosphate esters. The reported yields range from 50% to 95%. 

One of the earliest uses for rhodium(II)-catalyzed dipoles was demonstrated in Davies furan synthesis [22]. Isomiinchnones were also shown to produce substituted furans [115]. Additional furan syntheses have been described using silylacetates [116], unsaturated esters [117], and fluoroalkyl diazo acetates [118]. The synthesis of furofuranones and indenofuranones 35 from a-diazo ketones having pendant alkynes has also been reported (Eq. 6) [119]. Other fused heterocyclic systems include furo[3,4-c]furans [120, 121] furo[2,3-b]furans [122] as well as thiobenzofurans [123], and benzoxazoles[124] have also been synthesized with this methodology. 

Table 4. Asymmetric hydrolysis of esters from fluoroalkylated benzyl alcohol...

Since sulfur from the persulfate does not appear in the polymer, two possible reactions were suggested. The sulfate ion-radicals may initiate the polymerization to produce fluoroalkyl sulfuric acid esters which would be very rapidly hydrolyzed. 

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