Fluorinated 1-tetralone

Fluorination of the sodium enolate of 2-methyl-1-tetralone by (-)-A-tluoro-2,10-(3,3-dichlorocamphorsultam) gives (5 )-(- -)-2-iluoro-2-methyl-1-tetralone in 70% ee, which corresponds to the opposite asymmetric induction to that achieved using non-racemic (camphorsulfonyl)oxaziridines as closely related hydroxylation reagents. ... 

Asymmetric fluorination of the lithium enolate derived from tetralone 307 has been achieved with several new chiral A-fluoro-l,2-benzothiazine reagents (Scheme 44) <2000JOC7583, 2000CPB1954, see also 1999JFC(97)65>. For instance, sulfonamides 149 and 150 afford the opposite enantiomers of fluoroketone 308 in up to 79% yield and 62-70% ee. 

Trying to avoid too many hydrogens in sodium propionate we replaced die two in the a position with chlorine atoms. This time the reaction with fluorine at -75 °C resulted in a stable oxidizing solution. The low temperature F NMR spectrum revealed a sharp singlet at +134 ppm, a characteristic signal for the COOF fluorine nucleus. Also this oxidizer was reacted with the enol acetate of a-tetralone to give, in 85% yield, the... 

The Behenna-Stoltz protocol was soon applied to a-fluoroketones. As shown in Scheme 5.26, the silyl enol ethers 80 of 2-fluoro-indanone, tetralone-, and ben-zosuberone can be reacted with allyl or methallyl carbonate to give the tertiary a-fluorinated ketones 81 in 83-95% ee [43]. The procedure that was also applied to an allylation of 4,4-dimethyl-6-fluorocyclohexenone offers an alternative to the enantioselective fluorination of enolates on the one hand and the decarboxylative allylation of fluorinated P-keto esters on the other hand vide infra). 

SCHEME 9 Fluorination of tetralone silyl enol ethers 3 and 4. 

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