New reactions catalyzed by hydrogen bond donors are being discovered at an increasing pace, including asymmetric variants of common organic reactions useful for synthesis, such as aldol additions, Diels-Alder cycloadditions and Mannich reactions.
22.
An integral component of the Mannich reaction, in addition to an amine and a carbonyl compound, is a carbanion, which plays the role of the nucleophile in the nucleophilic addition to the ion formed by the reaction of the amine and the carbonyl.
23.
Related transformations of amines with a wide variety of other nucleophiles have been investigated, such as cyanide ( Strecker reaction ), silyl enol ethers ( Mannich reaction ), dialkylphosphates, allyl silanes ( aza-Sakurai reaction ), indoles ( Friedel-Crafts reaction ), and copper acetylides.
24.
The reaction taking place is between a simple aldehyde, such as propionaldehyde, and an imine derived from diastereoselective with a preference for the syn-Mannich reaction 3 : 1 when the alkyl substituent on the aldehyde is a methyl group or 19 : 1 when the alkyl group the much larger pentyl group.
25.
It undergoes Friedel-Crafts acylation with acetyl chloride and aluminium chloride to give the acyl derivative "'2 "', with formaldehyde and hydrochloric acid to the chloromethyl derivative "'3 "', in a Vilsmeier-Haack reaction with N-methylformanilide and phosphorus oxychloride to the formyl "'4 "', and in a Mannich reaction to amine derivative "'5 " '.
