One-Pot Construction of Aza- or Oxa-Bridged Benzocycloheptanes from Readily Available 2,3-Allenyl Malonates or 2,3-Allenols ando-Iodobenzaldehyde or Imine
摘要:
A Pd(OAc)(2)-catalyzed reaction of 2,3-alkadienyl malonates or 2,3-allenols with o-lodobenzaldehyde or Its N-tosyl imine occurred smoothly In MeCN at 80 degrees C to form the oxa- or aza-bridged benzocycloheptane derivatives with Important biological potential. With the optically active 2,3-allenols, the absolute configurations of all the three chiral centers have been conveniently established.
substrates 1 and 2 can be regioselectively converted into chiral allenyl alcohols 3 through the title reaction [Eq. (1)] with the synergetic reagent iPrSBEt2 and a chiral TiIV catalyst. The dramatic regioselectivity originates from the regulation of the equilibriumbetween propargyl- and allenylstannanes during the catalytic process.
Practical and efficient catalytic asymmetric allylic transfer reactions of achiral aldehydes with tin reagents promoted by BINOL-Ti(IV) complex are achieved with high enantioselectivity by the utilization of subjoined Lewis acid, B(OMe)3.