Fischers solution to the problem of sugar structures was actually much more diffi cultto

Chapter 24, Problem 62

(choose chapter or problem)

Fischers solution to the problem of sugar structures was actually much more diffi cultto achieve experimentally than Section 24-10 implies. For one thing, the only sugars that he couldreadily obtain from natural sources were glucose, mannose, and arabinose. (Erythrose and threosewere, in fact, not then available at all, either naturally or synthetically.) His ingenious solution requireda way to exchange the functionalities at C1 and C6 of glucose and mannose in order to make thecritical distinction described at the end of the section. (Of course, had gulose existed in nature, all thiseffort would have been unnecessary, but Fischer wasnt so lucky.) Fischers plan led to unexpecteddiffi culties, because at a key stage he got a troublesome mixture of products. Nowadays we solve theproblem in the manner shown below. Fill in the missing reagents and structures (a) through (g). UseFischer projections for all structures. Follow the instructions and hints in parentheses.D-()-Glucose (b)MethylD-glucoside(c)MethylD-glucuronoside(Both isomers;write only one)(a) O2, Pt(A special reactionthat oxidizes onlythe primary hydroxyat C6 into acarboxylic group)NaHg(Reduces lactonesto aldehydes)(d)D-Glucuronicacid(e) H2O Gulonicacid(f)Gulonolactone(Write theopen-chainform only)