1346905-78-9Relevant articles and documents
Catalyzed selective direct α- And γ-alkylation of aldehydes with cyclic benzyl ethers by using T+BF4- in the presence of an inexpensive organic acid or anhydride
Richter, Heinrich,Rohlmann, Renate,Garcia Mancheno, Olga
, p. 11622 - 11627 (2011)
The cross dehydrogenative coupling (CDC) of cyclic benzyl ethers with aliphatic and α,β-unsaturated aldehydes has been developed. The mild reaction conditions, in which an N-oxoammonium salt derived from TEMPO (2,2,6,6-tetramethyl-1-piperidinoxyl) is employed as the oxidant in combination with a Cu catalyst, allow the use of relatively redox-unstable aldehydes under oxidative CDC conditions. The addition of a catalytic amount of trifluoroacetic acid (TFA) or Ac2O facilitates the reaction and increases the efficiency and selectivity. In contrast to the expected α-alkylation obtained with aliphatic aldehydes, α,β-unsaturated aldehydes led preferentially to the more challenging γ-alkylated products. The utility of the developed methodology was demonstrated by the synthesis of isochromane-derived bioactive compounds, such as the dopamine antagonist sonepiprazole.
