Question

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An unknown pentose (C_5H_10O_5) A is treated with conc. HNO_3 giving optically inactive diacid B. Kiliani-Fischer chain elongation of A results in the formation of two epimeric hexose sugars, C and D, whose diacids (from HNO_3 oxidation) are both optically active (E and F, respectively). When subjected to the Fisher sequence (C1 - C6 interchange), hexose D affords L-glucose. Treatment of pentose A with aqueous bromine gives G, which undergoes decarboxylation in the presence of iron (III) and hydrogen peroxide to afford H. Lastly, HNO_3 oxidation of H gives D tartaric acid. Using your knowledge of organic transformations, draw the structures of compounds A through H as Fischer projections. Place your answers in the spaces provided below.

Answer 1

We are getting D-tarto ricacid as on。0f the produts, so Pentose is a Pentoge wi th Conc. HNos 9ives ophcally in ach'vo diac So pentose t is either D-mbose D-xylose Kilianyi -Fischer synthesis of D-ibose gives ballase and D-attotse chí ch aYe 0n Ovidation give an 야tically in active dia ad (D-allo.oica ad) So D-bose is not the equired pentoso Pentose A s D-yylose Conc HNOg 4 CH20 H D- xtylose oph cally in acive Fiseher synthesi's 40 CHO Fischer H o En chan CH2OH D-Gulose D-ldose HNOS CODH Coo H Opti colly ative di acios

CHO COOH CO2 CH20 나 Cu20H Conc N NO 2 CoOH