Highly selective rhodium-catalyzed conjugate addition reactions of 4-oxobutenamides.
A variety of 4-oxobutenamides 1 were subjected to rhodium-catalyzed conjugate addition with arylboronic acids providing high regio- and enantioselectivity (97:3 to >99:1, >96% ee) and moderate to excellent yields (54-99%). The key to high selectivity is the use of sterically demanding P-chiral diphosphines, such as Tangphos or Duanphos. The product oxobutanamides 2 may be converted to alternate targets by selective derivatization of either the amide or ketone functional group. A stereochemical model predicting the absolute sense of induction was developed based on single-crystal X-ray structures of product and precatalyst.
Zigterman
Jamie L
JL
Chemical Process Research and Development, Amgen Inc, Thousand Oaks, CA 91320-1799, USA.
Woo
Jacqueline C S
JC
Walker
Shawn D
SD
Tedrow
Jason S
JS
Borths
Christopher J
CJ
Bunel
Emilio E
EE
Faul
Margaret M
MM