The title aldehyde (-)-3 and its enantiomer (+)-3 have been prepared starting from furfuryl alcohol and acetone. The method involves the diastereoselective [4+3]-cycloaddition of 2-[(benzyloxy)methyl]furan and 1, 3-dibromo-2-oxyallyl cation giving adduct (+/-)-4 that was converted with high yield into (+)(2RS, 5RS, 6SR)- 5-azido -2-[(benzyloxy)methyl] -2, 3,5,6-tetrahydro-2, 6-bis (hydroxymethyl) -4H-pyran-4-one ((+/-)-9). Ketone (+/-)-9 was then transformed with high selectivity into (+/-)-(2RS,4RS,5SR,6RS)-5-azido-2-[(benzyloxy)methyl]-2, 3,5,6-tetrahydro-4-[(triethylsilyl)oxy]-6-{[(triisopropylsilyl)oxy]methy l}-2H-pyran-2-methanol (+)-3 that was resolved by the Alexakis-Mangeney method (column chromatography of aminals derived from (1R,2R)-1,2-diphenylethylenediamine). The absolute configuration of (-)-3 was established by circular dichroism and the Dale-Mosher method on derivatives. (C) 2001 Elsevier Science Ltd. All rights reserved.
Majed Chergui, Oliviero Cannelli, Giulia Fulvia Mancini, Malte Oppermann, Camila Bacellar Cases Da Silveira, Dominik Kinschel, Christian David, Jérôme Lacour