Interactions of various fluorinated and nonfluorinated alcohols with trans-stilbene in the presence of electrophilic reagents were studied. Under neat conditions, reactions of trans-stilbene (1) with fluorinated alcohols, R(f)OH (R(f) = CF3CH2-, CFH2CH2-, CF3CF2CH2-, CF2H(CF2)3CH2-, (CF3)2CH-, (CF3)3C- (2a-f) in the presence of an electrophilic reagent, 1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor) or N,N-difluoro-2,2'-bipyridinium bis(tetrafluoroborate) (MEC-31), gave alpha-keto ethers (3a-f) and benzil (4) in good to moderate yields. alpha-Keto ether and benzil formation was very much dependent on the reaction time, the degree of fluorination of the alcohols, and whether a solvent such as CH3CN, DMF or DMA was utilized. In solution, alpha-keto ethers and benzil did not form. Interestingly, under neat conditions, nonfluorinated alcohols, ROH (R = CH3-, CH3CH2-, CH3CH2CH2-, CH3CH2CH2CH2-, CH3CH2CH2CH2CH2CH2-) (5g-k) did not react with trans-stilbene in the presence of MEC-31 but gave 6,6'-dialkoxy-2,2'-bipyridines (6g-k), regioselectively, in excellent isolated yields. On the other hand, fluorinated alcohols did not react with MEC-31. Reaction of MEC-31 with an excess of diethylene glycol (7) gave the bipyridine derivative (8) in 88% isolated yield. Reaction of 8 either with diethylaminosulfur trifluoride (DAST) or bis(2-methoxyethyl)aminosulfur trifluoride (Deoxofluor) readily produced the corresponding difluoro derivative (9) in 85% isolated yield. All new compounds have been characterized by spectroscopic and elemental analysis.

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Base-Mediated Syntheses of New 6,6¢-Di(polyfluoroalkoxy)-2,2¢-Bipyridines with 100% Regioselectivity D i (p o l y f l u o r o a l k o x y)-2 , 2 ¢-Bip y r i d i n e s w i t h 1 0 0 % R e g i o s e l e c t i v i t y

Etherification Etherification O 0328Electrophilic Fluorinating Reagent Mediated Synthesis of Fluorinated α-Keto Ethers, Benzil, and 6,6'-Dialkoxy-2,2'-bipyridines. -New applications of difluorobipyridinium compound MEC and Selectfluor to produce α-keto polyfluoroalkylated ethers in good yields from (E)-stilbene and fluorinated alcohols are reported. Varying amounts of benzil are formed additionally in each case. Fluorinated alcohols are found to be unreactive with MEC in the absence of (E)-stilbene. On the other hand, the reaction of nonfluorinated alcohols with MEC (IV) affords alkoxylated bipyridines in excellent yields. Diol (VIII), derived from MEC and diethylene glycol, is fluorinated by Deoxo-Fluor or DAST to give the corresponding fluorinated product (IX). -(MANANDHAR, S.; SINGH, R. P.; EGGERS, G. V.; SHREEVE*, J. M.; J. Org. Chem. 67 (2002) 18, 6415-6420; Dep. Chem., Univ. Idaho, Moscow, ID 83843, USA; Eng.) -Klein 06-066