17.7 Lithium Enolates 17.8 α-Selenation: A Synthesis of α,β-Unsaturated Carbonyl Compounds 17.9 Additions to α,β-Unsaturated Aldehydes and Ketones

The aldols formed in aldol additions can be easily dehydrated to yield conjugated enals (enones)

If a chiral atom attached to the carbonyl group, the stereoselectivity of nucleophilic addition follows the Cram’s rule

The most characteristic reaction of aldehydes and ketones is nucleophilic addition to the carbon-oxygen double bond

Many other pairs of reagents that form cabocations (orcarbocationlike species) may be used as well

No addition of bromine No oxidation No hydroation Slow addition at high temperature and pressure

The reactivity of organometallic compounds increases with the percent ionic character of the carbon-metal bond. RLi and RMgX are of great importance in organic synthesis

11.15A Ethers by Intermolecular Dehydration of Alcohols

四川大学：华西药学院《生物有机与生物正交化学》课程教学大纲

Acid-Catalyzed hydration of Alkenes Oxymercuration-Demeruration Hydroboration-Oxidation