The Biginelli reaction is a one-pot (three-component) procedure that in the presence of an acid catalyst, converts a β-keto ester, an aryl aldehyde, and urea to a hexahydropyrimidine derivative. First, urea reacts with the aldehyde affording an aminal, which dehydrates to an N-acyliminium ion. The enol form of the β-keto...

The Dakin-West reaction uses a base to convert an amino acid and anhydride to an acylamino ketone. Acylation of both the nitrogen atom and the carboxylic acid group occur first, followed by an intramolecular acyl substitution, producing a protonated oxazolone intermediate. Further acylation of the oxazolone, acetoxy group additions, and...

The intramolecular condensation of a diester, producing a cyclic β-keto ester, is called the Dieckmann condensation. The base abstracts an α-proton from one of the esters, yielding an enolate ion that attacks the other ester, forming a tetrahedral intermediate. Alkoxide ion is released, followed by the formation of a second...

Proceeding through a concerted, aromatic transition state, the Diels-Alder [4π+2π] cycloaddition uses heat to form a cyclohexene derivative from an electron rich (s-cis) diene and an electron poor dienophile (referred to as the normal electron-demand Diels-Alder reaction). Benefits include the conservation of the starting dienophile’s stereochemistry and the high regioselectivity...

The formation of a C-C single bond between the α-position of a conjugated carbonyl compound and a carbon electrophile in the presence of a nucleophilic Lewis Base catalyst is known as the Baylis-Hillman reaction. A Michael addition of the catalyst occurs at the β-position of the conjugated carbonyl compound, forming...

The Cannizzaro reaction utilizes a strong base and two aldehydes with no α-hydrogens: one is reduced to the corresponding 1° alcohol, while the other is oxidized to a carboxylic acid in a maximum yield of 50% each. Although a variety of mechanisms have been proposed, the generally accepted mechanism involves...