Page 48 - Catalysts for Fine Chemical Synthesis Vol 1 - Robert & Poignant
P. 48
the integration of biotransformations into catalyst 31
CH 3 CH CHCONR 2 ). Later investigations showed the catalysts were also
effective stereocontrolling systems for the coupling of a maleimide to an acyclic
diene (Scheme 44) [130] .
Me Me
Ph
Ph
Me H Me
H HO
OH
CF 3 SO 2 N NSO 2 CF 3
Al
Me
(49) (50)
O H O
i
+ N N
MeO
O Me 3 C H O Me 3 C
MeO
95 % ee
Scheme 44: Reagents and conditions: i) CH 2 Cl 2 , ÿ78 C, 10±20 mol% catalyst (49).
The biaryl compound (50) forms a complex with diethylaluminium chloride
to provide a catalyst able to promote enantioselective reaction between cyclo-
pentadiene and methacrolein or acrylates (Scheme 45). The addition of di-tert
butyl 2,2-dimethylmalonate to the reaction mixture was found to enhance the
enantiomeric excess of the product [131] .
O
i
+ H
OMe
CO 2 Me
>99 % ee
76 % yield
Scheme 45: Reagents and conditions: i) (Me 3 CO 2 C) CMe 2 50 mol%, Et 2 AlCl and com-
2
pound (51) 10 mol% each, CH 2 Cl 2 , ÿ78 C to ÿ 40 C.
