Reaction of 2,2-difluorovinyl ketones with heteroatom nucleophiles: A general one-pot synthesis of α-oxoketene acetals
摘要:
2,2-Difluorovinyl ketones readily react with heteroatom nucleophiles such as thiols, alcohols, and amines to undergo stepwise replacement of the two fluorine atoms via addition-elimination process. The reaction affords alpha-oxoketene acetals including S,S-, N,S-, N,N-, O,S-, and O,O-acetals in good to excellent yields.
2,2,2-Trifluoroethyl p-toluenesulfonate is treated with butyllithium and trialkylboranes successively to generate 1-alkyl-2,2-difluorovinylboranes, which in turn react with acyl chlorides or chloroformates in the presence of cuprous iodide to afford 2,2-difluorovinyl carbonylcompounds in good yields.
regioselective manner viareplacement of the fluorine by the substituted nitrogen of the hydrazines and dehydration between the carbonyl group of 1 and the NH(2) end. The reactions are successfully effected for both aliphatic and aromatic hydrazines in aqueous ethanol under neutral conditions and in THF under basic conditions with butyllithium, respectively. A similar ring-forming reaction of 1 with hydrazine