The oxidation of primary and secondary alcohols with ketones in the presence of metal alkoxides such as aluminum isopropoxide (Al(i-PrO)3) to yield aldehydes and ketones is known as the Oppenauer oxidation. The alcohol substrate binds to aluminum, and the ketone coordinates to it, forming a six-membered transition state that allows...

The cobalt catalyzed formation of cyclopentenones from alkenes, alkynes and carbon monoxide is known as the Pauson-Khand reaction. The precise mechanism has not yet been fully elucidated, but previous studies have demonstrated that the larger alkyne substituent ends up next to the carbonyl group in the product. The regioselectivity with...

Generating α,β-unsaturated carboxylic acids (cinnamic acid derivatives) in the presence of a weak base from aromatic aldehydes with the anhydrides of aliphatic carboxylic acids is known as the Perkin reaction. An enolate intermediate is made from the anhydride, which undergoes a condensation reaction with benzaldehyde, followed by an intramolecular acyl...

The Pictet-Spengler reaction uses catalytic acid to convert a β-arylethylamine and an aldehyde or ketone to a substituted tetrahydroisoquinoline. First β-arylethylamine attacks the carbonyl carbon, forming a tetrahedral intermediate, which is dehydrated to afford the corresponding Schiff base. Upon protonation, a 6-endo-trig cyclization occurs, disrupting ring aromaticity. Loss of an...

The acid-catalyzed condensation of alkenes with aldehydes is known as the Prins reaction. A protonated aldehyde is attacked by the alkene to afford the most stable β-hydroxyl carbocation that can engage in various reaction pathways dependent on the reaction conditions: (i) Water and a hydrogen atom on the carbon adjacent...

The Reformatsky reaction uses zinc metal and an acid work-up to convert an α-haloester and an aldehyde or ketone to a β-hydroxyester. Zinc metal is first inserted into the carbon-halogen bond of the α-haloester, followed by the formation of an O-zinc enolate, which undergoes an aldol reaction with the carbonyl...