Hept-l-ynitol

Buchanan and co workers71 found that treatment of the 7 3 mixture of the D-altro (68) and D-alio (69) hept-l-ynitol derivatives obtained from 2,3,5-tri-O-benzyl-D-ribofuranose and ethynylmagnesium bromide with 2.2 equivalents of p-toluenesulfonyl chloride at 60° gives the 1-D-ribofuranosylethyne derivatives (70 and 71) in 52 and 13%... 

Cyclization72 of the D-allo-hept-l-ynitol derivative 72, obtained from 2,3-O-isopropylidene-D-ribofuranose and ethynylmagnesium bromide, leads in very high yield to the amorphous a-D-ribosylethyne derivative 73, which gave crystalline 1-a-D-ribofuranosylethyne (74) after acid hydrolysis. 

Adition of Grignard reagents. Reaction of 2,3-O-isopropylidene-D-ribose (62) with ethynyl magnesium bromide gives l,2-dideoxy-4,5-0-iso-propylidene-D-a//o-hept-l-ynitol (63), which is then converted into its 7-O-trityl ether (64). Treatment of 64 with TsCl/pyridine provides 2,3-0-isopropylidene-5-0-trityl-a-D-ribofuranosylethyne (65) which upon deprotection affords derivative 66 (Scheme 22).89... 

Mella, M, Panza, L, Ronchetti, F, Toma, L, l,2-Dideoxy-3,4-5,7-bis-0-(l-methylethylidene)-D-gluco and D-galacto-hept-l-ynitols — synthesis and conformational studies, Tetrahedron, 44, 1673-1678, 1988. 

O-Isopropylidene, 5-trityl 3,6-Anhy-dro-l,2-dideoxy-4,5-0-isopropylidene-7-O-trityl-D-ahro-hept-l-ynitol C29H28O4 440.538... 

A synthesis of a dimeric ribitol fragment of a capsular polysaccharide is mentioned in Chapters 3 and 7, and a one-carbon chain elongation procedure converting hexoses to hept-l-ynitols is referred to in Chapter 13. 

Buchanan s group has published details of the reaction of 2,3-C-isopro-pylidene-D-ribofuranose with ethynylmagnesium bromide to yield 1,2-dideoxy-4,5-C-isopropylidene-D-a//o-hept-l-ynitol, which was converted into its 7-trityl ether. Treatment of this trityl ether with toluene-/7-sulphonyl chloride in pyridine furnished 2,3-0-isopropylidene-5-C-trityl-a-D-ribofuranosylethyne (35). 

O-Isopropylidene 3,6-Anhydro-l,2-dideoxy-4,5-0-isopropylidene-D-a.lt[0-hept-1 -ynitol... 

Anhydro-4,5,7-tri-0-benzyl-l,2-dideoxy-D-a//o -hept-1-ynitol, R-105, 2-Dideoxy-D-arabino-hex-l-ynitol, H-120... 

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