Self-assembly of organocatalysts for the enantioselective Michael addition of aldehydes to nitroalkenes

A proline-thiourea self-assembled organocatalyst is described as a good catalyst for the enantioselective nitro-Michael addition of aldehydes to nitroalkenes The reaction is efficient with 5% of the thiourea, to give moderate to good enantioselectivity (up to 76% ee) High syn-selectivity was obtained with both branched and unbranched aliphatic aldehydes This is the first example of self-assembly of organocatalysts with an achiral additive in a Michael addition wherein aldehydes are utilized as donors. (c) 2009 Elsevier Ltd All rights reserved