Organocatalyzed direct aldol condensation using L-proline and BINAM-prolinamides: regio-, diastereo-, and enantioselective controlled synthesis of 1,2-diols

Recoverable BINAM-prolinamide derivatives, as well as L-proline, give results complementary to antibodies when used as organocatalysts for aldol eactions between aldehydes and α-alkoxyacetones driving regioselectively to anti/syn-1,2-diols. The formation of the iso-regioisomer is suppressed using α-hydroxyacetone in DMSO at rt, achieving the corresponding anti-1,2-diol with ee’s up to 85%. For α-alkoxyacetones (methoxy, benzyloxy, and tert-butyldimethylsilyloxy), the highest regio- and diastereoselectivity is achieved using α-methoxyacetone in DMF at 0 °C; the enantiomeric excess for the anti-1,2-isomer being up to 98%.This work was financially supported by the Dirección General de Investigación of the Ministerio de Educación y Ciencia of Spain (Grant BQU2001-0724-CO2-01 and CTQ2004-00808/BQU), the Generalitat Valenciana (Grant CTIOIB/2002/320, GRUPOS03/134, and GV05/157) and the University of Alicante