Regioselective Three-Component Synthesis of Vicinal Diamines via 1,2-Diamination of Styrenes

Iron(II)-Catalyzed 1,2-Diamination of Styrenes Installing a Terminal NH2 Group Alongside Unprotected Amines

1,2-Diamination of alkenes represents an attractive way to generate differentiated vicinal diamines, which are prevalent motifs in biologically active compounds and catalysts. However, existing methods are usually limited in scope and produce diamines where one or both nitrogens are protected, adding synthetic steps for deprotection and further N-functionalization to reach a desired target. Furthermore, the range of amino groups that can be introduced at the internal position is fairly limited. Here we describe a 1,2-diamination of styrenes that directly installs a free amino group at the terminal position and a wide variety of unprotected nitrogen nucleophiles (primary or secondary alkyl or aromatic amines, sulfoximines, N-heterocycles, and ammonia surrogate) at the internal position. Two complementary sets of conditions encompass electronically activated and deactivated styrenes with diverse substitution patterns and functional groups. Moreover, this strategy can be extended to the 1,2-aminothiolation of styrenes.

Catalytic Asymmetric Aza-Electrophilic Additions of 1,1-Disubstituted Styrenes

Electrophilic addition of alkenes is a textbook reaction that plays a pivotal role in organic chemistry. In the past decades, catalytic asymmetric variants of this important type of reaction have witnessed great achievements by the development of novel catalytic systems. However, enantioselective aza-electrophilic additions of unactivated alkenes, which could provide a transformative strategy for the preparation of synthetically significant nitrogen-containing compounds, still remain a formidable challenge. Herein, we have developed unprecedented Au(I)/NHC-catalyzed asymmetric aza-electrophilic additions of unactivated 1,1-disubstituted styrenes by the utilization of readily available dialkyl azodicarboxylates as electrophilic nitrogen sources. Based on this approach, a series of transformations, including [2 + 2] cycloaddition, intermolecular 1,2-oxyamination, and several types of intramolecular hydrazination-induced cyclizations, have been realized. These transformations provide a previously unattainable platform for the divergent synthesis of hydrazine derivatives, which could also be converted to other nitrogen-containing chiral synthons. Experimental and computational studies support the idea that carbocation intermediates are involved in reaction pathways.

Cobalt-catalyzed amination of aziridines and azetidines toward 1,2- and 1,3-diamines

Diamines play important roles in synthetic organic chemistry and thus facilitate life and materials sciences. Herein we report a cobalt-catalyzed ring opening, nucleophilic amination of aziridines and azetidines with N-fluorosulfonamides toward a wide range of 1,2- and 1,3-diamine derivatives in moderate to good yields under mild conditions.

Photoredox-catalyzed unsymmetrical diamination of alkenes for access to vicinal diamines

A photoredox-catalyzed unsymmetrical diamination of alkenes by using N-aminopyridinium salts and nitriles as the amination reagents has been developed. Various vicinal diamines were obtained in moderate to excellent yields under mild reaction conditions. Furthermore, this protocol could be applied in the late-stage modification of pharmaceuticals and natural products. Preliminary mechanistic studies suggested that this methodology may undergo a radical pathway followed by a Ritter-type reaction.

Catalytic Enantioselective Aminative Difunctionalization of Alkenes

Enantioselective difunctionalization of alkenes offers a straightforward means for the rapid construction of enantioenriched complex molecules. Despite the tremendous efforts devoted to this field, enantioselective aminative difunctionalization remains a challenge, particularly through an electrophilic addition fashion. Herein, we report an unprecedented approach for the enantioselective aminative difunctionalization of alkenes via copper-catalyzed electrophilic addition with external azo compounds as nitrogen sources. A series of valuable cyclic hydrazine derivatives via either [3 + 2] cycloaddition or intramolecular cyclization have been achieved in high chemo-, regio-, enantio-, and diastereoselectivities. In this transformation, a wide range of functional groups, such as carboxylic acid, hydroxy, amide, sulfonamide, and aryl groups, could serve as nucleophiles. Importantly, a new cyano oxazoline chiral ligand was found to play a crucial role in the control of enantioselectivity.

Cobalt-Promoted Photoredox 1,2-Amidoamination of Alkenes with N-Sulfonamidopyridin-1-ium Salts and Free Amines

A cobalt-promoted photoredox 1,2-amidoamination of alkenes with N-sulfonamidopyridin-1-ium salts and free amines for the synthesis of unsymmetrical vicinal diamines has been developed. The reaction handles N-(sulfonamido)pyridin-1-ium salts as the sulfonamidyl radical precursors and free amines as the nucleophilic terminating reagents to enable the formation of two new C(sp3)-N bonds in a single reaction step and offers a route to selectively producing unsymmetrical vicinal diamines with an exquisite selectivity and a good compatibility of functional groups.

Transition-Metal-Catalyzed 1,2-Diaminations of Olefins: Synthetic Methodologies and Mechanistic Studies

1,2-Diamines are synthetically important motifs in organo-catalysis, natural products, and drug research. Continuous utilization of transition-metal based catalyst in direct 1,2-diamination of olefines, in contrast to metal-free transformations, with numerous impressive advances made in recent years (2015-2023). This review summarized contemporary research on the transition-metal catalyzed/mediated [e. g., Cu(II), Pd(II), Fe(II), Rh(III), Ir(III), and Co(II)] 1,2-diamination (asymmetric and non-asymmetric) especially emphasizing the recent synthetic methodologies and mechanistic understandings. Moreover, up-to-date discussion on (i) paramount role of oxidant and catalyst (ii) key achievements (iii) generality and uniqueness, (iv) synthetic limitations or future challenges, and (v) future opportunities are summarized related to this potential area.

Ring Opening of Aziridines by Pendant Sulfamates Allows for Regioselective and Stereospecific Preparation of Vicinal Diamines

The ring opening of aziridines by pendant sulfamates is a viable strategy for the rapid preparation of vicinal diamines. Our reaction is compatible with both disubstituted cis- and trans-aziridines; unsubstituted, N-alkyl, and N-aryl sulfamates engage effectively. In all cases examined, the cyclization reaction is perfectly regioselective and stereospecific. Once activated, the product oxathiazinane heterocycles can be ring opened with a diverse range of nucleophiles.

Intermolecular Hydrazinative Halogenation of Alkenes with Potassium Halides as Nucleophilic Halogen Sources: Modular Entry to Phenelzine Derivatives

An approach for the efficient synthesis of halogenated hydrazines via acid-mediated electrophilic hydrazinative halogenation of alkenes is disclosed. This transformation proceeds with readily available diethyl azodicarboxylate as a hydrazine source and low-cost potassium halides as nucleophilic halogen sources. A series of iodinated, brominated, and chlorinated hydrazines are facilely produced with a wide range of functional groups. The obtained products are good platform molecules. They can be conveniently converted into a variety of valuable phenelzine analogues which are appealing for development of novel drugs treating depression.

Hydrazinolysis Products of Selected Sugar Lactones-Crystal Structure and Microbiological Activity

Commercially available lactones, as well as those synthesized by us, turned out to be good substrates for the synthesis of sugar hydrazides. The exception was L-ascorbic acid, whose hydrazinolysis led to the formation of a hydrazinium salt, not the hydrazide as expected. The structure of all compounds was confirmed by NMR and X-ray analyses. The lower durability of hydrazinium L-ascorbate was additionally confirmed by thermogravimetric tests. All products were tested for biological activity against Gram-negative bacteria strains Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 and against Gram-positive Staphylococcus aureus ATCC 25923 and Staphylococcus aureus ATCC 29213. Their antifungal activity against Candida albicans SC5314, Candida glabrata DSM 11226 SM 11226, Candida krusei DSM 6128, and Candida parapsilosis DSM 5784 was also tested. The most interesting results of microbiological activity were obtained for D-gluconic acid hydrazide and hydrazinium L-ascorbate. The results of the latter encourage more extensive testing.

Tandem Oxidative Ritter Reaction/Hydration/Aldol Condensation of α-Arylketones with Propiolonitriles for the Construction of 3-Acyl-3-pyrrolin-2-ones

A novel tandem oxidative Ritter reaction/hydration/aldol condensation of α-arylketones with substituted propiolonitriles has been developed. This protocol conveniently affords a wide range of functionalized 3-acyl-3-pyrrolin-2-ones through the efficient construction of four chemical bonds, a C-N bond, a C═C bond, and two C═O bonds, and the formation of one ring bearing an aza-quaternary center, which is ascribed to the strategical introduction of functionalized nitriles to this transformation. A reaction mechanism was proposed based on some control experiments.

Recent Advancements on Metal-Free Vicinal Diamination of Alkenes: Synthetic Strategies and Mechanistic Insights

The oxidative aminative vicinal difunctionalization of alkenes or related chemical feedstocks has emerged as sustainable and multipurpose strategies that can efficiently construct two -N bonds, and simultaneously prepare the synthetically fascinating molecules and catalysis in organic synthesis that typically required multi-step reactions. This review summarized the impressive breakthroughs on synthetic methodologies (2015-2022) documented especially over inter/intra-molecular vicinal diamination of alkenes with electron-rich or deficient diverse nitrogen sources. These unprecedented strategies predominantly involved iodine-based reagents/catalysts, which resent the interest of organic chemists due to their impressive role as flexible, non-toxic, and environmentally friendly reagents, resulting in a wide variety of synthetically useful organic molecules. Moreover, the information collected also describes the significant role of catalyst, terminal oxidant, substrate scope, synthetic applications, and their unsuccessful results to highlight the limitations. Special emphasis has been given to proposed mechanistic pathways to determine the key factors governing the issues of regioselectivity, enantioselectivity, and diastereoselectivity ratios.

Copper-Catalyzed Nitrogen Atom Transfer to Isoquinolines via C-N Triple Bond Cleavage and Three-Component Cyclization

A copper(I)-catalyzed tandem reaction of 2-bromoaryl ketones, terminal alkynes, and CH₃CN is developed, which combines N atom transfer and three-component [3 + 2 + 1] cyclization, and efficiently produces densely functionalized isoquinolines in a facile, highly selective, and general manner. In the reaction, the formation of aromatic C-N bonds along with the complete C-N triple bond cleavage is first realized; Cu(III)-acetylide species might serve as the intermediates, which allow highly selective 6-endo-dig cyclization.