THE ADDITION OF DIBROMODIFLUOROMETHANE TO (TRIMETHYLSILYL)ACETYLENE AND TRANSFORMATION OF THE PRODUCTS

Reaction of dibromodifluoromethane (1) with (trimethylsilyl)acetylene (2) initiated by ammonium persulfate/sodium formate ((NH4)(2)S2O8/HCO2 Na) yield the addition-reduction product (3a), tribromide compound (3b ) and the non-fluorinated compound (4) which could be separated by car eful distillation. The reaction appears to be initiated by CO2.-. Indi um mediated coupling of 3a with aldehydes gave the corresponding gem-d ifluorohomoallyl alcohols bearing a trimethylsilyl group 8 in high yie lds. In the presence of indium, 3b reacted with aldehydes to afford th e coupling-reduction product gem-difluorohomoallyl alcohols 9. The reg iochemistry of this reaction and the retention of the configuration of double bond could be rationalized in terms of the more nucleophilic a lpha-carbon of the gem-difluoroallyl intermediate. (C) 1998 Elsevier s cience Ltd. All rights reserved.