Trifluoroacetic acid-mediated facile transformation of 2-C-hydroxymethyl-D-glycals to chiral pyrano[2,3-b]benzopyrans

Treatment of 2-C-hydroxymetilyi-D-glyCalS With phenols in trifluoroacetic acid at ambient temperature leads to an extremely facile transformation affording chiral pyrano[2,3-b]benzopyrans in high yields. (C) 2008 Elsevier Ltd. All rights reserved.