Abstract
The synthesis of novel l-prolinal dithioacetal and its application as an organocatalyst for the direct Michael
addition of cyclic ketones and acetophenone derivatives to trans-β-nitrostyrene and related compounds is described. The prolinal dithioacetal acts
as effective catalyst in the case of cyclic ketones of different ring size, in particular
five- and six-membered examples, as well as larger and smaller ring systems. High
enantioselectivity and diastereoselectivity is observed for different substrates and
trans-β-nitrostyrenes. Also, the first asymmetric syntheses of selected 2-methyl-4-nitro-1,3-diphenylbutan-1-one
derivatives by application of the obtained organocatalyst is presented.
Key words
asymmetric catalysis - C–C bond formation - catalyst design - Michael reaction