Cross silyl benzoin additions catalyzed by lanthanum tricyanide.
From a screen of (cyanide)metal complexes, an improved catalyst for the cross silyl benzoin addition was discovered. Several M(CN)(3) complexes (M = Ce, Er, Sm, Y, Yb, La) were evaluated and lanthanum tricyanide was identified as the optimal catalyst. The catalyst, prepared in situ from LaCl(3), effects the selective coupling of aryl and alkyl acylsilanes with aryl, heteroaryl, alpha,beta-unsaturated, and aliphatic aldehydes. The reactions occur at ambient temperature in less than 5 min to provide, depending on the workup, alpha-hydroxy or alpha-silyloxy ketones in 48-93% isolated yield.
Bausch
Cory C
CC
Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
Johnson
Jeffrey S
JS