Tungsten-Catalyzed Allylic Substitution with a Heteroatom Nucleophile: Reaction Development and Synthetic Applications

Molybdenum-Catalyzed Regio- and Enantioselective Amination of Allylic Carbonates: Total Synthesis of (S)-Clopidogrel

The first molybdenum-catalyzed highly regio- and enantioselective allylic amination of both aryl- and alkyl-substituted branched allylic carbonates has been developed. A wide variety of amines, including drugs and complex bioactive molecules, underwent successful amination with excellent reaction outcomes (up to 96% yield, >99% ee, and >20:1 b/l). The reaction could be scaled up and has been applied to the total synthesis of chiral drug molecule (S)-clopidogrel (Plavix).

Green Chemistry Approach toward the Regioselective Synthesis of α,α-Disubstituted Allylic Amines

Molybdenum-catalyzed allylic substitution reactions are known to provide direct and practical ways to construct new carbon-carbon bonds and privileged compounds. However, due to the lack of reports on carbon-heteroatom bond formation as a common deficiency, these reactions still face a great challenge. Described herein is a robust and convenient molybdenum-catalyzed regioselective allylic amination of tertiary allylic carbonates with an amine as the heteroatom nucleophile. Both aromatic and aliphatic amines react with various tertiary allylic alcohol derivatives to deliver the desired α,α-disubstituted allylic amines in high yield with complete regioselectivity. In addition, ethanol as the green solvent, a recyclable catalyst system through simple centrifugation techniques, and simple handling procedures make the current approach green, economic, and sustainable.

Pd-Catalyzed Multicomponent Cross-Coupling of Allyl Esters with Alkyl Bromides and Potassium Metabisulfite: Access to Allylic Sulfones

A Pd-catalyzed multicomponent cross-coupling of allyl esters with alkyl bromides to synthesize allylic sulfones by using K2S2O5 as a connector is first reported. The reaction displays a broad range of substrate generality along with excellent functional group compatibility and produces the products with high regioselectivity (only E). Furthermore, the biologically active molecules with a late-stage modification, including aspirin, menthol, borneol, and estrone, are also highly compatible with the multicomponent cross-coupling reaction. Mechanistic studies indicate that the process of SO2 insertion into the C-Pd bond was involved in this transformation.

Beyond classical sulfone chemistry: metal- and photocatalytic approaches for C-S bond functionalization of sulfones

The exceptional versatility of sulfones has been extensively exploited in organic synthesis across several decades. Since the first demonstration in 2005 that sulfones can participate in Pd-catalysed Suzuki-Miyaura type reactions, tremendous advances in catalytic desulfitative functionalizations have opened a new area of research with burgeoning activity in recent years. This emerging field is displaying sulfone derivatives as a new class of substrates enabling catalytic C-C and C-X bond construction. In this review, we will discuss new facets of sulfone reactivity toward further expanding the flexibility of C-S bonds, with an emphasis on key mechanistic features. The inherent challenges confronting the development of these strategies will be presented, along with the potential application of this chemistry for the synthesis of natural products. Taken together, this knowledge should stimulate impactful improvements on the use of sulfones in catalytic desulfitative C-C and C-X bond formation. A main goal of this article is to bring this technology to the mainstream catalysis practice and to serve as inspiration for new perspectives in catalytic transformations.

1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP)-Assisted Catalyst-Free Sulfonation of Allylic Alcohols with Sulfinyl Amides

A highly regioselective and catalyst-free sulfonation of allylic alcohols with sulfinyl amides has been realized. Such a mix-and-go procedure provides a convenient approach to synthetically various allylic sulfones under mild reaction conditions. Furthermore, this novel reaction shows ample substrate scope and outstanding functional group tolerance and could also be scaled-up. Meanwhile, it is the first example that sulfinyl amides act as a powerful sulfur nucleophile in the reactions. 1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP) as a solvent plays a critical role in allylic sulfonation.

Regio- and enantioselective formation of tetrazole-bearing quaternary stereocenters via palladium-catalyzed allylic amination

A general and efficient method via catalysis by readily available Pd(0)/DACH-naphthyl catalyst under mild conditions, unlocks a new platform that permits the synthesis of elusive quaternary N2-allylic tetrazoles, even in the context of late-stage functionalization.

Selective approach to N-substituted tertiary 2-pyridones

Commercially available 2-hydroxypyridines are converted into enantiomerically enriched allylic 2-pyridones with elusive N-substituted tertiary carbon by means of Pd-catalyzed allylic amination of vinyl cyclic carbonates.

Temperature Controlled Di- and Monosulfonylation of Propargyl Alcohols with Sodium Sulfinates: Switchable Access to (E)-Allyl, Vinyldisulfones and Propargyl Sulfones

A switchable di- and monosulfonylation of propargyl alcohols with sodium sulfinates is developed, which successfully affords (E)-allyl, vinyldisulfones and propargyl sulfones in good to excellent yields, respectively. The salient features...