704 CARBOHYDRATES Cyclization gives the a-and B-furanose forms of L-arabinose OH H OH H HOCH HOCH ar-L-Arabinofuranose B-L-Arabinofuranose In the L series the anomeric hydroxyl is up in the a isomer and down in the B isomer. (d) The Fischer projection formula for D-threose is given in the text Figure 25. 2. Reorientation of that projection into a form that illustrates its potential for cyclization is shown 10-tH is equivalent to 4 H CHOH Cyclization yields the two stereoisomeric furanose forms H H 0 H HO H HO B-D-Threofuranose a-D-Threofuranose 25.6 (b) The Fischer projection and Haworth formula for D-mannose are CHO HO-H HOCH HO-H OH OH 1o HO CS HOHO OH CHOH D-Mannose mannopyranose The Haworth formula is more realistically drawn as the following chair conformation HOCH HO- OH H Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE WebsiteCyclization gives the - and -furanose forms of L-arabinose. In the L series the anomeric hydroxyl is up in the isomer and down in the isomer. (d) The Fischer projection formula for D-threose is given in the text Figure 25.2. Reorientation of that projection into a form that illustrates its potential for cyclization is shown. Cyclization yields the two stereoisomeric furanose forms. 25.6 (b) The Fischer projection and Haworth formula for D-mannose are The Haworth formula is more realistically drawn as the following chair conformation: HO HO H H OH H H H OH HOCH2 O -d-Mannopyranose CHO CH2OH HO H OH H OH H HO H d-Mannose H HO HO OH H H HO H CH2OH -d-Mannopyranose (Haworth formula) H HO OH H HO H HOCH2 H HO H O C O H H HO OH H 4 3 2 O H 1  -d-Threofuranose OH H H HO HO H O -d-Threofuranose H OH H HO HO H O C O H H HO OH H 4 3 2 O H 1 d-Threose CH2OH HO H OH H C H 1 O 2 3 4 is equivalent to C O H -l-Arabinofuranose H HOCH2 OH H OH H H OH O -l-Arabinofuranose H HOCH2 H OH OH H H OH O 704 CARBOHYDRATES Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website