4. An iterative approach to oligosaccharide synthesis involves the use of protected glycals (sugars with C1-C2 double bond) as shown below. The product from the reaction of the first glycal with DMDO under anhydrous conditions is treated with another suitably-protected glycal to form a disaccharide glycal, and the process can be repeated to form a trisaccharide glycal, and so on... Crucial to the success of this approach is the stereoselective formation of the intermediate A in the scheme below. Draw the structure of A. DMDO CH₂Cl2 A OH ZnCl₂, THF OH

Which of the following best describes the disaccharide shown here? HO OH OH HO OH OH AmoH HO A. a-1,4' glycoside of D-glucose and D-galactose B. B-1,3' glycoside of D-glucose and D-galactose C. a-1,4' glycoside of D-galactose and D-glucose D. B-1,4' glycoside of D-gulose and D-galactose E. a-1,3' glycoside of D-allose and D-glucose F. a-1,3' glycoside of D-altrose and D-galactose G. a-1,3' glycoside of D-idose and D-idose H. B-1,3' glycoside of D-altrose and D-galactose O A OB OC OD OE OF OG OH F3 1-0 F4 FS MacBook Air FB

Compare the following monosaccharides and choose the best description. a. same sugar b. enantiomers c. diastereomers d. different sugars

Select the glycoside(s) that are formed when the following monosaccharide is treated with CH3CH₂OH, HCI. HO OH OH HO- НО. OH OCH₂CH₂ OH OH OH OCH₂CH₂ OH OH OH -OH HO OH OH OH С HO- OH CH3CH₂OH HCI OH OH OCH₂CH3 -OCH₂CH3 a НО НО OH OH OH OH OH OCH₂CH₂ OCH₂CH₂ Lo -OH HO OCH CH НО. OH OH -0 OH OCH₂CH₂ OH -OH OCH₂CH₂