Question

Which of the following is methyl- $\alpha -D$ -glucoside?
(i)
(ii)
(iii)
(iv)
(v)

• A. (i)
• B. (ii)
• C. (iii)
• D. (iv)

Answer 1

Answer: (A)

$\alpha $ -D-Glucoside has methoxy and ethanol group attached on carbons bonded as $C-O-C$ . So option $3,4$ and $5$ can be discarded as the groups are far away from each other. Now we look at option $1,2$ . In $\alpha $ -D- glucoside, we have $3OH$ groups and a methoxy and ethanol group. The methoxy and ethanol groups are Trans to each other whereas the alcohol group attached adjacent to carbon of methoxy and ethanol are cis and Trans respectively. Now we are left with just one alcohol which is in direction of ethanol.So the structure would be as,