Two Birds with One Metallic Stone: Single‐Pot Catalysis of Fundamentally Different Transformations

Abstract

Advances in metal catalysis have revolutionized organic synthesis, with the scope of metal-catalyzed reactions now covering nearly all areas of carbon-carbon, carbon-hydrogen, and carbon-heteroatom bond formation. For years, the goal was to develop catalysts that were highly selective for a single transformation. However, a promising current area of research is the use of a single catalyst to mediate more than one transformation in a selective manner. Whereas much early work was focused on using a catalyst for several similar transformations, recent investigations have shown that it is also possible to employ a single catalyst for several very different transformations in a single reaction sequence. This Minireview focuses on methods in which the mechanisms of the transformations are fundamentally very different.

Indium(III) Chloride‐Catalyzed Propargylation/Amination/Cycloisomerization Tandem Reaction: One‐Pot Synthesis of Highly Substituted Pyrroles from Propargylic Alcohols, 1,3‐Dicarbonyl Compounds and Primary Amines

“…Unfortunately, the optically active primary amine 3g could not afford the desired product under the same reaction conditions, possibly due to the steric bulkiness of 3g. Further screening of various catalysts led to the discovery that the use of the combination of CuA C H T U N G T R E N N U N G (OTf) 2 and AgOTf was ideal, providing the desired pyrrole 6kg in 86% isolated yield (Table 3, entry 7), with the stereogenic centre in the initial amine not being affected during the transformation. However, the trimethylsilyl group could not be tolerated under this condition and had fallen off during work-up.…”

“…[3][4][5][6][7] The corresponding multicomponent coupling reactions proceeding directly from simple and readily available substrates are much less studied. Recently, efficient sequential reactions of propargylic alcohols, carbonyl compounds and primary amines in the presence of [Cp*RuClA C H T U N G T R E N N U N G (m 2 -SMe) 2 RuCp*Cl]/PtCl 2 [8] or CF 3 CO 2 H/Ru(II), [9] which lead to the synthesis of substituted pyrroles, have been reported. However, two or more catalysts are needed in these reactions.…”

“…[1] Especially, the finding and utilization of a single catalyst to promote several transformations in a selective manner is a promising area of research. [2] Such direct synthesis routes help to avoid side-product formation and loss of starting material as well as to reduce capital investment and operation costs.…”

Copper(I)‐Catalyzed Cascade Synthesis of 2‐Arylsulfanyl‐ arylcyanamides

“…[1] Of all the metal catalysts, the Cu-catalyzed inter-and intramolecular domino reactions involving carbon-heteroatom bond formations for the synthesis of a wide variety of heterocycles have advantages over the others in terms of efficacy, selectivity and low cost. [2] Even though the chemistry of Cu-catalyzed C À C, C À N and C À O bond formations is well explored, [3] methods available for C À S bond formation are relatively fewer in the literature, which of course is growing in number.…”

Co-Catalyzed Tandem Pauson-Khand Type Reaction/Dimerization of Terminal Diynes in the Presence of Cyclopentadiene under CO Pressure

“…1,2 In particular, if an intermediate is highly reactive, its further transformation in a single operation will broaden the utility of the highly reactive intermediate molecule in organic synthesis. Synthesis of novel cyclic compounds through cobalt carbonyl-catalyzed tandem cyclization including the Pauson-Khand and the related reaction has been one of our current research themes.…”