Fluoroacetate allyl

Namely, allyl alcohol is successively treated with diethylzinc, (R,R) dipropyl tartrate, and 4-methoxybenzohydroximinoyl chloride (163) to afford the enantiomeric isoxazoline alcohol 166, which under the Jones oxidation conditions affords the corresponding carboxylic acid derivative (167). Treatment of compound 167 with hydroxylamine-O-triflate followed by tri-fluoroacetic acid gives rise to the desired enantiomeric 165 in high excess enantiomeric yield. The synthesis of other isosteric analogues of 165 was reported in the same paper. None of the isosteric analogues exhibits LpxC inhibitory and antibacterial activities [103]. 

Ireland-Claisen rearrangement, in the case of anions of allyl fluoroacetates. 

Allylic esters of fluoroacetic acid were used in the Ireland silyl ketene acetal rearrangement procedures by the Welch group at Albany [164]. For example, Eq. (53) shows a highly diastereoselective rearrangement which formed an early stage in syntheses of 2,3-dideoxy-2-fluoro-3-C-methyl pentose nucleosides [165, 166]. If a stereoselective synthesis of a functionalised monofluorocompound is... 

Tabic 21. Synthesis of 2-Fluoroalk-4-enoic Acids 16 by the Ireland-Claiscn Rearrangement of Allylic Fluoroacetates 15... 

Hydroxysulphenylation. The reaction of these two reagents in CH2Cl2/tri-fluoroacetic acid with allylic esters gives vic-trifluoroacetoxy sulfides, which are hydrolyzed to vic-hydroxy sulfides. The reaction with allyl acetate (equation I)... 

Among oxi tions producing allylic alcohols or their derivatives the modem variants of selenium dioxide oxidations are by far the most popular. Systems based on metal acetates, particularly palladium tri-fluoroacetate, can be very useful and are receiving increasing attention but the Kharasch-Sosnovsky reaction, once very common for allylic oxidation, is now rarely used. Sensitized photooxidation with singlet oxygen, a very well-known procedure, is still somewhat unpredictable and has periu K received less consideration than it deserves. 

Some complexes dissociate fully in solution (e.g., 7r-allyl nickel tri-fluoroacetate) whence [63] Rp cc [C2][M]. Donor solvents (triphenyl-phosphite, nitrobenzene) can also coordinate with the metal and influence catalyst dissociation with effects on rate and polymer molecular weight the structure of the polymer may also be affected [173]. 

In a related reaction, treatment of the lithinm salt of diethyl (l-phenylsulfonyl)ethylphosphonate with triflnoroacetic anhydride affords triflnoroacetylated phosphonate, which, without isolation, reacts with Grignard reagents in THF at reflux to give trifluoromethylated vinylsulfones in 42-55% yields, with the formation of ( )-isomer exclusively or predominantly. Treatment of the lithium salt of diethyl 1-fluoro-l-(ethoxycarbonyl)methylphosphonate with trimethylsilyl trifluoroacetate leads to the enolate of ethyl (trifluoroacetyl)fluoroacetate, which can further undergo protonation, alkylation, or allylation. °5... 

The nucleophile is the enolate anion from ethyl 2-fluoroacetate 30 formed with NaH in the presence of n-Hex4N+Br. The complex 28 would be achiral except for the ligand which directs the nucleophile to one end of the allyl cation on the opposite face to the palladium. With only 1 mol% of the catalyst up to 96% ee was achieved though only one centre in 31 is controlled. 

In the rearrangement of allyl fluoroacetates, trialkylsilyl triflates have been introduced as a new reagent for the Z-selective generation of silyl ketene acetals485. Thus, when (T)-crotyl fluoroacetates are treated at ambient temperatures with a trialkylsilyl triflate in the presence of a tertiary amine, rearranged products with a svn relationship are preferentially obtained. The ketene acetal intermediates cannot be isolated and the geometry has been deduced from the stereochemistry of the products. The selectivity of this process improves in the order triisopropyl > ferf-butyldimethylsilyl > rerf-hexyldimethylsilyl > trimethylsilyl a triethylsilyl (see Table 11). 

Rearrangements. Ireland-Claisen rearrangement of allyl fluoroacetates, formation of /3-(W-acylamino)aldehydes from 0-vinyl-N,0-acetals, 1,2-group migra-tion/trapping are some of the useful transformations initiated by TMSOTf. ... 

The Nakai conditions in some cases can lead to greatly increased stereoselectivities relative to the Ireland conditions. Welch et al. found that use of sUyl triflates could lead to significantly improved diastereoselectivities and/or yields in the rearrangement of allyl fluoroacetates (Scheme 4.51) [53]. Rearrangement of the Z-crotyl fluoroacetate under the Nakai conditions proceeded via the Z-silyl ketene acetal and afforded excellent yield and high diastereoselectivity for the anti isomer Treat-... 

Each of the cyclic amines shown below has been synthesized by reaction of an amino-substituted allylic silane with formaldehyde in the presence of tri-fluoroacetic acid. Identify the appropriate precursor of each amine and suggest a method for its synthesis. 

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