Enantiomerically pure tetrahydroisoquinolines by enzyme catalysis and gold-catalyzed phenol synthesis

Five different furfural derivatives were converted to chiral cyanohydrins by enzyme catalysis in good enantiomeric excess. After a sequence of silyl protection, nitrile reduction, tosylation and propargylation, Substrates for the gold(I) catalyzed cycloisomerization of delta-alkynyl furans delivered good yields of enantiomerically pure dihydroxytetrahydroisoquinoline building blocks. Neither racemization nor elimination to quinolines was observed. (C) 2008 Elsevier Ltd. All rights reserved.