A new synthesis of trifluoromethylated cyclohexenes (original) (raw)
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Journal of Fluorine Chemistry, 1999
Reaction of 5,5,5-tri¯uoro-4-(tri¯uoromethyl)penta-3-en-2-one (1) with p-toluene-sulfonylhydrazines under basic conditions provided anti-Michael addition products. Acid-catalyzed reactions yielded the expected hydrazones. In the absence of solvent the reaction of (CH 3) 3 SiCl with 1 gave the corresponding silylenolether (3), which did not yield cross condensation products with ketones. In the presence of TiCl 4 silylenolether (3) reacted at À788C to give the corresponding nonadienone (11). Analogously at 208C condensation with water elimination gave the pyran system (12). The yields of 11 and 12 were increased by adding ZnCl 2. It is interesting to note that trimethylsiloxycyclohexene reacted with 1 in a Mukaiyama-aldol-condensation to the corresponding cross condensation product 13. Starting from (CF 3) 2 C=C(CN) 2 and a mixture of (E/Z)-1,3-pentadiene the expected cyclohexene was formed. One of the two CN-groups was removed with NaOH in C 2 H 5 OH/H 2 O. A second double bond was introduced in an allylic position of the hexene ring by bromination and elimination with (C 2 H 5) 3 N to yield the diene. Reduction with DIBAlH provided the aldehyde 7,7,7,8,8,8-hexa¯uorosafranal. Hydrogenation of the C3±C4 double bond in the presence of palladium on a charcoal catalyst led to 7,7,7,8,8,8-hexa¯uoro-cyclocitral. Xray structures of selected compounds are provided.
Trifluoromethyl ethers – synthesis and properties of an unusual substituent
Beilstein Journal of Organic Chemistry, 2008
After nitrogen, fluorine is probably the next most favorite hetero-atom for incorporation into small molecules in life scienceoriented research. This review focuses on a particular fluorinated substituent, the trifluoromethoxy group, which is finding increased utility as a substituent in bioactives, but it is still perhaps the least well understood fluorine substituent in currency. The present review will give an overview of the synthesis, properties and reactivity of this important substituent.
ChemInform Abstract: A Convenient Route to Trifluoromethyl-Substituted Cyclopropane Derivatives
ChemInform, 2008
A range of alkenes have been converted in a single step into the corresponding trifluoromethyl-substituted cyclopropanes by treatment with 2-diazo-l,l,l-trifluoroethane over metal catalysts. Application of the Gaspar-Roth procedure allowed the preparation of target compounds on a multi-gram scale. The practical utility of this reaction has been demonstrated by the synthesis of both diastereoisomers of the non-natural amino acid trifluoronorcoronamic acid in two steps.
Polyfluoroalkylated 2-ethoxymethylene- 3-oxo esters: synthesis and chemical properties overview
Pure and Applied Chemistry, 2017
The review focuses on the synthesis and chemical properties of polyfluoroalkylated 2-ethoxymethylene-3-oxo esters. The scope and peculiarities of their use as organic reagents in reactions with various N-, C-, O-, mono- and dinucleophiles are discussed in detail. The high reactivity of such derivatives is employed in the construction of enaminoketone, arene and heterocycle frameworks. Particular attention is paid to applications of these building blocks as chemicals for fine organic synthesis, bioactive compounds and metal complexes synthesis.
Tri- and tetrasubstituted α-fluorocyclohexanones with enantiomeric excesses in the range of 97–100%
Tetrahedron: Asymmetry, 2001
The a-fluorinated trisubstituted ketones (2S,5R)-(−)-7-Ia, (2R,5R)-(+)-7-IIe, (2S,5R)-(−)-8-Ia and (2R,5R)-(+)-8-IIe were synthesised from (+)-dihydrocarvone (99% (R)-configuration at C-5) and fully characterised. a-Fluorinated tetrasubstituted ketones (−)-9-Ia, (+)-9-Ia, (+)-9-IIa and (+)-10-Ia having e.e.s of ]97% were synthesised as racemates from 3-methyl cyclohexenone then resolved into the pure enantiomers using chiral HPLC and fully characterised.