Cycloalkanones boron trifluoride complex

A variation of the above reaction involves the boron trifluoride etherate-catalyzed condensation of gi OT-dihydroper-oxides 240 with dimethyl and diethyl acetals 243 (method C, Scheme 45) <2004S2356>. The gi OT-dihydroperoxides 240 were prepared from cycloalkanone dimethyl or diethyl acetals 242 by treatment with hydrogen peroxide catalyzed by boron trifluoride complexes <2003TL7359> or similarly from appropriate enol ethers <2004RCB681>. 

Various condensations of cyclo-octanone to give 2,2 -dialkylcyclo-octa-nones, and with ethyl cyanoacetate, have been reported. The u.v. spectra of boron trifluoride complexes of cycloalkanones and the i.r. spectra of titanium tetrachloride complexes have been studied. Reactions of benzo-cycloheptanone are discussed. ... 

The reaction of methyl (S)-4-methylbenzenesulfmate with cyclic silyl enol ethers under catalysis with boron trifluoride diethyl ether complex leads to addition to the enolate17. The resulting sulfoxide-substituted cycloalkanones, e.g., 15, are versatile starting materials for further reactions with chirality transfer from sulfur to carbon (Section D.5.). 

N.m.r. data for several unsaturated ketones and the corresponding alkenes, saturated ketones, and alkanes, have been analysed in terms of n-electron densities. Included are data for cyclohepta-2,7-dienone, cyclo-octa-2,4-dienone, cyclohept-2-enone, cyclo-oct-2-ene, and tropone. The n.m.r. spectra of several di-esters, including medium-ring examples, have been reported. Boron trifluoride complexa-tion of cycloalkanones has been studied using n.m.r. at low temperatures (— 85 to —125 °C) separate signals for both the complexed ( 24 p.p.m. downfield) and free ketones were observed. ... 

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