Effects of Substituents in the β-Position of 1,3-Dicarbonyl Compounds in Bromodimethylsulfonium Bromide-Catalyzed Multicomponent Reactions: A Facile Access to Functionalized Piperidines

Abstract

1,3-Dicarbonyl compounds can be converted to Mannich-type products A or highly functionalized piperidines B in the presence of a catalytic amount of bromodimethylsulfonium bromide (BDMS). The combination of aromatic aldehyde, amine, and 1,3-dicarbonyl compounds in the presence of a catalytic amount of BDMS leads to the formation of Mannich-type product A when R is a non-enolizable carbon or an alkoxy group, whereas in cases when R = CH3, the same combination yielded highly functionalized piperidines B. A synthetic study and mechanistic proposal are presented.

One-pot multi-component green synthesis of highly substituted piperidines

“…The results are presented in Table 3. Based on previous literature records, 13,[16][17][18][19][20][21][22][23] it is reasonable to assume following mechanism of the reaction. Piperidines 4 results from initial condensation of aromatic aldehydes (1) and β-ketoesters This reaction can be regarded as an efficient approach for the preparation of synthetically and pharmaceuptically important piperidine systems.…”

Synthesis of Highly Functionalized Piperidines by One-Pot Multicomponent Reaction Using Boron Trifluoride Etherate

“…The results are briefly mentioned in Table 1. The products were characterized by 1 H NMR, 13 C NMR, IR and mass etc. …”

Methyl Acetoacetate: A Useful Reagent in Multicomponent Reactions

“…4 Replacing methylacetoacetate by diethyl malonate in the presence of the same catalyst yields the Mannich-type products. 5 (C) Synthesis of Substituted Pyrazoles: Substituted pyrazoles have received much attention because of their useful pharmacological properties.…”