Caravano Audrey, Field Robert A, Percy Jonathan M, Rinaudo Giuseppe, Roig Ricard, Singh Kuldip
Department of Chemistry, University of Leicester, University Road, Leicester LE17RH, UK.
Org Biomol Chem. 2009 Mar 7;7(5):996-1008. doi: 10.1039/b815342f. Epub 2009 Jan 23.
Free radical bromination and nucleophilic fluorination allows the conversion of methyl sorbate into the 6-fluoro analogue which undergoes sequential asymmetric dihydroxylation reactions. A range of 6-deoxy-6-fluorosugars were prepared by using different combinations of ligands. While the enantiomeric excesses obtained were comparable to those from other 6-substituted sorbates, the regioselectivity of dihydroxylation was moderate, with both 2,3- and 4,5-diols being obtained. A successful temporary persilylation strategy was evolved to convert the products of dihydroxylation rapidly to the fluorosugars 6-deoxy-6-fluoro-L-idose, 6-fluoro-L-fucose and 6-deoxy-6-fluoro-D-galactose, which were obtained in overall yields of 4%, 6% and 8% from methyl 6-fluoro-hexa-2E,4E-dienoate .
自由基溴化和亲核氟化可将山梨酸甲酯转化为6-氟类似物，该类似物可进行连续的不对称双羟基化反应。通过使用不同配体组合制备了一系列6-脱氧-6-氟糖。虽然获得的对映体过量与其他6-取代山梨酸酯的相当，但双羟基化的区域选择性适中，同时得到了2,3-二醇和4,5-二醇。一种成功的临时全硅烷基化策略得以发展，可将双羟基化产物迅速转化为氟糖6-脱氧-6-氟-L-艾杜糖、6-氟-L-岩藻糖和6-脱氧-6-氟-D-半乳糖，从6-氟-2E,4E-己二烯酸甲酯出发，它们的总产率分别为4%、6%和8%。
