Diversity‐Orientated Stereoselective Synthesis through Pd‐Catalyzed Switchable Decarboxylative C−N/C−S Bond Formation in Allylic Surrogates

Divergent Synthesis of Dihydrofuran and Dienol Scaffolds via Pd-Catalyzed Decarboxylative Carbene Cross-Coupling

Herein, we report a novel ligand-switchable Pd-catalyzed carbene coupling reaction employing vinylethylene carbonates and sulfoxonium ylides. By proper choice of ligands, the chemoselectivity of the process could be efficiently regulated, allowing for the availability of dihydrofuran or dienol scaffolds. This method features mild reaction conditions, broad scope, and remarkable synthetic utility. Compound 6f can effectively stimulate the secretion of GLP-1, providing promising insight into the development of small-molecule agonists for the GLP-1 receptor.

Chemo-, Regio- and Stereoselective Preparation of (Z)-2-Butene-1,4-Diol Monoesters via Pd-Catalyzed Decarboxylative Acyloxylation

(Z)-alkenes are useful synthons but thermodynamically less stable than their (E)-isomers and typically more difficult to prepare. The synthesis of 1,4-hetero-bifunctionalized (Z)-alkenes is particularly challenging due to the inherent regio- and stereoselectivity issues. Herein we demonstrate a general, chemoselective and direct synthesis of (Z)-2-butene-1,4-diol monoesters. The protocol operates within a Pd-catalyzed decarboxylative acyloxylation regime involving vinyl ethylene carbonates (VECs) and various carboxylic acids as the reaction partners under mild and operationally attractive conditions. The newly developed process allows access to a structurally diverse pool of (Z)-2-butene-1,4-diol monoesters in good yields and with excellent regio- and stereoselectivity. Various synthetic transformations of the obtained (Z)-2-butene-1,4-diol monoesters demonstrate how these synthons are of great use to rapidly diversify the portfolio of these formal desymmetrized (Z)-alkenes.

Palladium-catalyzed (Z)-selective allylation of phosphine oxides with vinylethylene carbonates to construct phosphorus allyl alcohols

Allylphosphine oxide compounds are important building blocks with broad applications in organic synthesis and pharmaceutical science. Herein, we report an unprecedented palladium-catalyzed allylation of phosphine oxides with vinylethylene carbonates, producing various phosphorus allyl alcohols in excellent yields with high Z-selectivity. In addition, gram-scale synthesis and further functional group transformations demonstrate the practical utility of this synthetic method.

Palladium-catalyzed decarboxylative allylation of vinyloxazolidin-2-ones with sodium sulfinates: stereoselective assembly of highly functionalized (Z)-allylic amines

We report a general approach to highly functionalized (Z)-allylic amines by decarboxylative allylation of vinyloxazolidin-2-ones. This process engages sodium sulfinates as nucleophiles to form a new carbon-sulfur bond, utilizing a palladium catalyst generated from Pd(OAc)2 and diphosphine ligand dpppe. The scope of the protocol is illustrated by the synthesis of 30 representative allylic amines with high regio- and stereoselectivity. Mechanistic studies show that the Z-selectivity of the reaction stems from the formation of a palladacycle intermediate through Pd-N chelation. The synthetic utility of this method was further exemplified by the gram-scale synthesis and subsequent transformations to various compounds.

Palladium-catalyzed stereoselective decarboxylative allylation of azlactones: access to (Z)-trisubstituted allylic amino acid derivatives

A palladium-catalyzed stereoselective decarboxylative allylation of azlactones with vinyl methylene cyclic carbonates affords a series of trisubstituted allylic amino acid derivatives in good yields with an exclusive (Z)-configuration.

Marine furanocembranoids-inspired macrocycles enabled by Pd-catalyzed unactivated C(sp3)-H olefination mediated by donor/donor carbenes

Biomimetic modularization and function-oriented synthesis of structurally diversified natural product-like macrocycles in a step-economical fashion is highly desirable. Inspired by marine furanocembranoids, herein, we synthesize diverse alkenes substituted furan-embedded macrolactams via a modular biomimetic assembly strategy. The success of this assembly is the development of crucial Pd-catalyzed carbene coupling between ene-yne-ketones as donor/donor carbene precursors and unactivated Csp³‒H bonds which represents a great challenge in organic synthesis. Notably, this method not only obviates the use of unstable, explosive, and toxic diazo compounds, but also can be amenable to allenyl ketones carbene precursors. DFT calculations demonstrate that a formal 1,4-Pd shift could be involved in the mechanism. Moreover, the collected furanocembranoids-like macrolactams show significant anti-inflammatory activities against TNF-α, IL-6, and IL-1β and the cytotoxicity is comparable to Dexamethasone.

Furanocembranoid-like natural products with the alkene-substituted furan scaffold display a range of biological activities, but are difficult to access. Here, the authors report a modular biomimetic strategy to synthesise diverse alkene-substituted furan-containing macrolactams via palladium-catalysed unactivated Csp³-H olefination.

Rh-Catalyzed C-H alkylation enabling modular synthesis of CF3-substituted benzannulated macrocyclic inhibitors of B cell responses

Inspired by aspirin and chalcone, herein, we describe a modular biomimetic strategy to achieve a new class of CF3-bearing benzannulated macrolactams. The key to the success of macrolactams was the utilization of a highly chemoselective Rh(iii)-catalyzed native carboxylic acid-directed C-H alkylation. Moreover, the unique CF3-containing benzannulated macrocycles showed decent immunosuppressive effects on B cells in vitro, including proliferation, activation, and antibody production upon specific stimulation implicating TLR and BCR signaling.

Palladium-catalyzed asymmetric allylic amination of a vinylethylene carbonate with N-heteroaromatics

Highly enantioselective allylic amination of a vinylethylene carbonate with N-heteroaromatics is enabled by asymmetric palladium catalysis for the synthesis of chiral acyclic nucleosides and isonucleosides.

Recent Advances in the Synthesis of Sulfides, Sulfoxides and Sulfones via C-S Bond Construction from Non-Halide Substrates

The construction of a C-S bond is a powerful strategy for the synthesis of sulfur containing compounds including sulfides, sulfoxides, and sulfones. Recent methodological developments have revealed lots of novel protocols for C-S bond formation, providing easy access to sulfur containing compounds. Unlike traditional Ullmann typed C-S coupling reaction, the recently developed reactions frequently use non-halide compounds, such as diazo compounds and simple arenes/alkanes instead of aryl halides as substrates. On the other hand, novel C-S coupling reaction pathways involving thiyl radicals have emerged as an important strategy to construct C-S bonds. In this review, we focus on the recent advances on the synthesis of sulfides, sulfoxides, and sulfones from non-halide substrates involving C-S bond construction.

Silver-promoted oxidative sulfonylation and ring-expansion of vinylcyclopropanes with sodium sulfinates leading to dihydronaphthalene derivatives

Silver-promoted sulfonylation and ring-expansion of vinylcyclopropanes with sodium sulfinates is established for the construction of 1-sulfonylmethylated 3,4-dihydronaphthalenes. This sulfonylation process involves a radical pathway, including sulfonyl radical formation, radical addition, ring-opening and cyclization. The 1-sulfonylmethylated 3,4-dihydronaphthalenes can be converted into other useful products.

Palladium nanoparticles as efficient catalyst for C-S bond formation reactions

The development of green, economical and sustainable chemical processes is one of the primary challenges in organic synthesis. Herein, we report an efficient and heterogeneous palladium-catalyzed sulfonylation of vinyl cyclic carbonates with sodium sulfinates via decarboxylative cross-coupling. Both aliphatic and aromatic sulfinate salts react with various vinyl cyclic carbonates to deliver the desired allylic sulfones featuring tri- and even tetrasubstituted olefin scaffolds in high yields with excellent selectivity. The process needs only 2 mol% of Pd2(dba)3 and the in situ formed palladium nano-particles are found to be the active catalyst.

Palladium-Catalyzed Regio- and Stereoselective Cross-Coupling of Vinylethylene Carbonates with Ketimine Esters to Generate (Z)-Tri- and Tetra-substituted Allylic Amino Acid Derivatives

Herein we report the palladium-catalyzed regio- and stereoselective cross-coupling of vinylethylene carbonates with ketimine esters to construct allylic amino acid scaffolds. This operationally simple protocol furnished (Z)-tri- and tetra-substituted allylic amino acid derivatives in good to excellent yields with distinguished geometric control under mild reaction conditions and proved to be sufficient in large-scale synthesis while retaining excellent reactivity and stereoselectivity, highlighting the practical value of this transformation.

A modular biomimetic strategy for the synthesis of macrolide P-glycoprotein inhibitors via Rh-catalyzed C-H activation

One of the key challenges to overcome multidrug resistance (MDR) in cancer is the development of more effective and general strategies to discover bioactive scaffolds. Inspired by natural products, we describe a strategy to achieve this goal by modular biomimetic synthesis of scaffolds of (Z)-allylic-supported macrolides. Herein, an Rh(III)-catalyzed native carboxylic acid-directed and solvent-free C−H activation allylation with high stereoselectivity and chemoselectivity is achieved. The generated poly-substituted allylic alcohol as a multifunctional and biomimetic building block is crucial for the synthesis of (Z)-allylic-supported macrolides. Moreover, the unique allylic-supported macrolides significantly potentiate the sensitivity of tumor cells to cytotoxic agents such as vinorelbine and doxetaxel by reversing p170-glycoprotein-mediated MDR. Our findings will inspire the evolution of synthetic chemistry and open avenues for expedient and diversified synthesis of bioactive macrocyclic molecules.

One strategy to address multidrug resistance in cancer is the development of modular methods to access bioactive scaffolds. Here, the authors report a Rh(III)-catalyzed carboxylic acid-directed C(sp²)−H allylation and apply it to the modular synthesis of (Z)-allylic macrolides which enhance antitumoral drug activity.

Palladium-catalysed decarboxylative annulations of vinylethylene carbonates leading to diverse functionalised heterocycles

This review provides an overview of the palladium-catalysed diverse cyclisations of VECs over the past five years, which could offer powerful synthetic tools to access various functionalised heterocycles.

An Update of Transition Metal-Catalyzed Decarboxylative Transformations of Cyclic Carbonates and Carbamates

Functionalized cyclic organic carbonates and carbamates are frequently used in a number of transition metal-catalyzed decarboxylative reactions for the construction of interesting molecules. These decarboxylative transformations have attracted more and more research attention in recent years mainly due to their advantages of less waste generation and versatile reactivities. On the basis of previous reviews on this hot topic, the present review will focus on the development of transition metal-catalyzed decarboxylative transformations of functionalized cyclic carbonates and carbamates in the last two years.