Asymmetric conjugate addition of carbonyl compounds to nitroalkenes catalyzed by chiral bifunctional thioureas

The effect of hydrogen bond donors in asymmetric organocatalytic conjugate additions

“…3 In a subsequent study, we also found that the structurally related thioureas are also good catalysts for the reaction. 4 Although we expected that the more acidic N-H bond in the sulfamides could provide better catalytic efficiency than in the corresponding thioureas, a reliable conclusion could not be achieved by the present experiment results. We become interested in the effect of the acidity of the N-H bond and the hydrogen-bonding modes on the catalytic activity and stereoselectivity of bifunctional primary amine organocatalysts.…”

Enantioselective Organocatalytic Michael Additions of Oxyacetaldehydes to Nitroolefins

“…[14] Enantioselective addition of aldehydes to β-nitroacrolein dimethyl acetal was published by Vicario. [15] The best results (up to 88 % ee) were achieved with simple prolinol as the catalyst.…”

Highly Enantioselective Michael Additions of Isobutyraldehyde to Nitroalkenes Promoted by Amphiphilic Bifunctional Primary Amine‐Thioureas in Organic or Aqueous Medium

“…Inspired by the pioneering work of Tanaka and Barbas III,2a who first reported asymmetric Michael additions of isobutyraldehyde to nitroalkenes catalyzed by ( S )‐(+)‐1‐(2‐pyrrolidinylmethyl)pyrrolidine/TFA, a great number of efforts have been devoted to the development of more selective and efficient catalytic systems 2. Only a few of these organocatalysts, however, have provided excellent enantioselectivity for transformations of this type 2g,2h,2l,2m. On the other hand, it should be noted that no success had previously been encountered in attempts to prepare both enantiomers of adducts selectively through organocatalytic Michael additions between isobutyraldehyde and nitroalkenes.…”