Topics in Current Chemistry (2020) 378:1
1 3
report that the organocatalyst alone was unable to promote the aldol reaction of
the cyclohexanone with aldehydes, and the presence of the Lewis acid was mandatory in order to observe the reaction. Chiral prolinamides based on cyclohexanediamine were investigated by Fu [69], as catalysts able to promote the formation of
β-hydroxy ketones in good diastereoselectivities (dr up to 99:1) and high enantioselectivities (up to 99% ee) (Scheme 6). The reaction was carried out in EtOH:H 2 O as
reaction solvent employing ZnCl 2 as Lewis acid catalyst (10 mol%). What is particularly interesting about this work is the possibility to perform larger-scale asymmetric aldol reactions on 20 mmol of aromatic aldehydes, using a catalyst loading of
10 mol%, with quite good stereoselection.
Scheme 5 Primary amine-metal Lewis acid bifunctional catalyst
Scheme 6 Asymmetric aldol reactions of cyclohexanone with various aryl aldehydes in the presence of
water
Reprinted from the journal
40
1 3
report that the organocatalyst alone was unable to promote the aldol reaction of
the cyclohexanone with aldehydes, and the presence of the Lewis acid was mandatory in order to observe the reaction. Chiral prolinamides based on cyclohexanediamine were investigated by Fu [69], as catalysts able to promote the formation of
β-hydroxy ketones in good diastereoselectivities (dr up to 99:1) and high enantioselectivities (up to 99% ee) (Scheme 6). The reaction was carried out in EtOH:H 2 O as
reaction solvent employing ZnCl 2 as Lewis acid catalyst (10 mol%). What is particularly interesting about this work is the possibility to perform larger-scale asymmetric aldol reactions on 20 mmol of aromatic aldehydes, using a catalyst loading of
10 mol%, with quite good stereoselection.
Scheme 5 Primary amine-metal Lewis acid bifunctional catalyst
Scheme 6 Asymmetric aldol reactions of cyclohexanone with various aryl aldehydes in the presence of
water
Reprinted from the journal
40