BIO 360 Chapter : Module 4_ Lesson 2 Carbohydrate Cyclization
Document Summary
Aldehydes attacked by alcohols ( hemlacetais) ketones attacked by alcohols ( hemiketals) Cyclization of monosaccharides ketone: nucleophilic alcohol attacks electrophilic carbonyl carbon . > allows formation ofahemlacetal: linear carbs forma ring structure chair forms of b-dglucopyranose, at completion , carbonyl carbon is reduced -10 an alcohol orientation of alcohol around carbon is variable and transient. Pentoses + hexoses readily undergo intramolecular cyclization former carbonyl carbon becomes achiral center / anomeric carbon) Hydroxyl group on the opposite side (trans)0f+he ring as chzoh moiety ; configuration isai. Hydroxyl group on the same side ( cis) ofthe. B- dg /ucopyranose nngasctl. ch moiety; configuration / sb. Furan pypanoses and futanoses cyclohexane rings "chair. Multiple "chair " conformations possible; require energy for interconversion (~ 46kg / mole) six membered oxygen -containing rings pyranoseslpyranring structure) five membered oxygen - containing rings furanoseslfuranring structure) anomeric carbon usually drawn on the right-side. B- d glucosamine n - acetyl -b- ? glucosamine o.
