A novel domino cyclization for the stereoselective synthesis of indeno[2,1-c]pyran and cyclopenta[c]pyran derivativesElectronic supplementary information (ESI) available: Copies of 1H and 13C NMR specta of products. CCDC 1044784. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5ob00376h

A novel bicyclization of 2-(2-(hydroxymethyl)-1-methylene-2,3-dihydro-1 H -inden-2-yl)ethanol with aldehydes in the presence of 10 mol% BF 3 ·OEt 2 in dichloromethane at 0-25 °C affords the biologically relevant indeno[2,1- c ]pyran scaffolds in good yields with high selectivity. Similarly the bicyclization of 2-(1-(hydroxymethyl)-2-methylenecyclopentyl)ethanol with aldehydes generates the corresponding cyclopenta[ c ]pyran derivatives under similar conditions. This method is very useful to produce hematoxylin and brazilin like scaffolds. A domino cyclization of exo -methylenediol and aldehydes with 10 mol% BF 3 ·OEt 2 provides the indeno[2,1- c ]pyran scaffolds in good yields.