Palladium‐Catalyzed Cascade Carbonylation to α,β‐Unsaturated Piperidones via Selective Cleavage of Carbon–Carbon Triple Bonds

Abstract

Ad irect and selective synthesis of a,b-unsaturated piperidones by an ew palladium-catalyzed cascade carbonylation is described. In the presented protocol, easily available propargylic alcohols react with aliphatic amines to provide abroad variety of interesting heterocycles.Key to the success of this transformation is ar emarkable catalytic cleavage of the present carbon-carbon triple bond by using aspecific catalyst with 2-diphenylphosphinopyridine as ligand and appropriate reaction conditions.M echanistic studies and control experiments revealed branched unsaturated acid 11 as crucial intermediate. Scheme 1. a) Summary of the main catalytic methods for CCcleavage. b) Summary of the main currently available synthetic methods for a,b-unsaturated piperidones. c) This work. d) Selected examples of biologically active molecules.

Enzyme-Graphene Nanometal biohybrid Architectures as Highly Efficient Multifunctional Catalysts for Cascade Reactions

“…8). 53 First cascade tested involved enzymatic hydrolytic activity followed by metallic oxidative activity of G@CALB-CuNPs hybrids to transform peracetylated glucose (5) (Fig. 8).…”

“…Catalytic cascade reactions are considered one of the most sustainable ways to produce complex structures from relatively simple starting materials. [1][2][3][4][5][6][7][8] These processes present advantages when compared to the typical single reaction, such as atom economy, step-saving, and therefore high yield and efficiency of the chemical process. Among the different catalytic methodologies to perform cascade reactions, systems that combines the wide reactivity of chemocatalysts and the unbeatable selectivity of biocatalysts have shown great application potential in chemical synthesis.…”

Solid‐Phase Lipase‐CuNPs Biohybrids as Catalysts for One‐Pot Parallel Synthesis of 2,3,4‐Triacetyl‐D‐Gluconic Acid

“…The development of cascade or parallel reaction systems represents the perfect strategy to produce these semiprotected monosaccharides, as they display several advantages compared to a typical single reaction, such as atom economy, step‐saving, and high yield, therefore providing high efficiency to the chemical process [8–11] …”

“…[7] The development of cascade or parallel reaction systems represents the perfect strategy to produce these semiprotected monosaccharides, as they display several advantages compared to a typical single reaction, such as atom economy, step-saving, and high yield, therefore providing high efficiency to the chemical process. [8][9][10][11] In particular, regioselective biocatalytic strategies and metal-catalysis have been successfully applied in carbohydrate chemistry, [12] thus a combination of both would be an ideal task, low exploited until now. [13] However, a proper design of enzyme-metal combination is challenging, because these two types of catalysts often deactivate mutually and the reaction conditions for one cannot be applied to the other.…”

Palladium-Catalyzed Three-Component Regioselective Dehydrogenative Coupling of Indoles, 2-Methylbut-2-ene, and Carboxylic Acids

“…Herein, we reported an unprecedented three-component dehydrogenative cascade coupling of indoles, 2-methylbut-2-ene, and carboxylic acids (Scheme e). It is known that the three-component cascade reaction is difficult in balancing the compatibility of reactant partners and the speed of individual elementary steps . Note that, unlike the previous reports of the introduction of five-carbon structural units usually at their C2′ and C4′ positions, , this approach selectively bonds a five-carbon structural unit at the C3′ position.…”