25.4The confguration at C-5 is opposite to that ofD-(1)-glyceraldehyde. This particular carbohydratetherefore belongs to theLseries. Comparing it with the Fischer projection formulas of the eightD-aldohexoses reveals it to be in the mirror image ofD-(1)-talose; it isL-(2)-talose25.5(b)The Fischer projection formula of D-arabinose may be found in text Figure 25.2. The Fischerprojection and the eclipsed conformation corresponding to it areCyclic hemiacetal formation between the carbonyl group and the C-4 hydroxyl yields the a- and b-furanose forms of D-arabinose.(c)The mirror image of D-arabinose [from part (b)] is L-arabinose.The C-4 atom of the eclipsed conformation ofL-arabinose must be rotated 120°in a clock-wise sense so as to bring its hydroxyl group into the proper orientation for furanose ring
This is the end of the preview. Sign up
access the rest of the document.