Sugars, difluorinated

C-6,209,214 anhydro sugars,branched monosaccharides, fluori-nated amino sugars,difluorinated monosaccharides, and fluorinated monosaccharide phosphates,and phosphonates have been described. Further progress has been achieved in the synthesis and n.m.r.-spectral analysis of fluorinated avermectin Bu, tylono-lide, and neuraminic acid derivatives. " ... 

Tables V-LVII detail H and F shift and coupling information, and Tables LVIII to LXXI incorporate the C-n.m.r. data. The data within this compilation are arranged according to the following outline hexoses prior to pentoses, followed by anhydro sugars, sugar acids and lactones, amino sugars (and their synthetic, A -containing precursors), mono-, di-, and tri-deoxy sugars, branched derivatives, ketoses, polyfluorinated monosaccharides, and, finally, difluorinated amino sugars. Within this compilation, and even within each table, pyranoid derivatives are listed prior to their furanoid counterparts, hexoses prior to pentoses, functionalized prior to deoxy compounds the arrangement within each sub-table is made alphabetically.

MONO- AND DIFLUORINATED ANALOGUES OF SUGARS 6.2.1 Fluorinated Furanoses and Nucleosides... 

Diethylaminosulfur trifluoride (DAST) has become one of the most important fluorinating agents (75JOC574,75JOU72 76JOU973 870R513). It is mainly used to transform alcohols, aldehydes, or ketones into mono-or difluorinated compounds. It has been used successfully in sugar, nucleo-... 

More recent examples of cyclooctene formation have been reported where cyclization was achieved without the need for annulation. For example, Percy has reported the syntheses of difluorinated cyclooctenones en route to conformationaUy locked sugar mimics (Scheme 2.46). " These cy-clizations were aided by a judicious choice of protecting group (vide supra) RCM of benzyl-protected 47 proceeded at 2.2 mmol L in 46% yield, while the benzoyl-protected substrate 45 underwent RCM at 10 mmol in 75% yield. Collectively, these results illustrate that synthesis of cyclooctenes can be challenging, and that the outcome of such reactions can acutely depend on substrate structure. 

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