Question

Draw the major product for each of the following reactions, showing the correct stereochemistry. (Include H\'s on chirality centers.)

Answer 1

Alcohols undergo nucleophilic substitution reactions only if the OH group is converted into a better leaving group before nucleophilic attack. Thus, substitution does not occur when an alcohol is treated with HX with X- because OH- is a poor leaving group, but the substitution does occur on treatment of an alcohol HBr он Br PBr3 converts the alcohols into alkyl bromides. The mechanism for this reaction consists of two parts conversion of the OH group into a better leaving group, and nucleophilic attack by Br-via an SN2 reaction PBr, pyridine он Reaction of alcohols with tosylates gives an alkyl tosylate which is further reacted with sodium bromide gives an alkyl bromide. The reaction undergoes nucleophilic substitution reaction by the SN2 mechanism 1.TsCl, pyridine IH 2.NaBr он Br