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In the present manuscript, we reported the first visible‐light‐enabled direct C3−H alkylation/arylation of quinoxalin‐2(1H)‐ones with unactivated alkyl/aryl chlorides under metal‐free conditions. A wide range of unactivated alkyl and aryl chlorides containing different functionalities are coupled with a variety of quinoxalin‐2(1H)‐one derivatives under mild reaction conditions to afford the C3‐alkyl/aryl substituted quinoxalin‐2(1H)‐ones in moderate to good yields. [ABSTRACT FROM AUTHOR]

The first rhodium‐catalyzed formylation of non‐activated alkyl chlorides with syn gas (H2/CO) allows to produce aldehydes in high yields (25 examples). A catalyst optimization study revealed Rh(acac)(CO)2 in the presence of 1,3‐bisdiphenylphosphinopropane (DPPP) as the most active catalyst system for this transformation. Key for the success of the reaction is the addition of sodium iodide (NaI) to the reaction system, which leads to the formation of activated alkyl iodides as intermediates. Depending on the reaction conditions, either the linear or branched aldehydes can be preferentially obtained, which is explained by a different mechanism. [ABSTRACT FROM AUTHOR]

Transition‐metal‐catalyzed cross‐coupling chemistry can be regarded as one of the most powerful protocols to construct carbon–carbon bonds. While the field is still dominated by palladium catalysis, there is an increasing interest to develop protocols that utilize cheaper and more sustainable metal sources. Herein, we report a selective, practical, and fast iron‐based cross‐coupling reaction that enables the formation of Csp−Csp3 and Csp2−Csp3 bonds. In a telescoped flow process, the reaction can be combined with the Grignard reagent synthesis. Moreover, flow allows the use of a supporting ligand to be avoided without eroding the reaction selectivity. [ABSTRACT FROM AUTHOR]

Short gram‐scale asymmetric syntheses of asperazine, pestalazine A, and their unnatural congeners thereof, have been achieved in ≈10 steps by using readily accessible starting materials. The nickel‐catalyzed reductive coupling protocol was utilized as a key step for the direct construction of C3asp3−C7′sp2 bond furnishing the diaryl‐substituted quaternary carbon centers with remarkable steric hindrance. The streamlined access to this core structure of heterodimeric tryptophans under the mild reaction conditions, makes this strategy hold a great promise in the concise synthesis of other relevant oligomeric pyrroloindoline alkaloids with unique C3a−C7′ linkages. Highly efficient syntheses of bioactive alkaloids (+)‐asperazine and (+)‐pestalazine A were realized by means of Ni‐catalyzed reductive coupling between 7‐iodotryptophan and 3‐chlorocyclotryptophan derivatives. This key reaction secured the construction of C3a−C7′ bond and the associated sterically congested all‐carbon quaternary stereocenter in a single step. [ABSTRACT FROM AUTHOR]

Abstract: A general formamide‐catalyzed protocol for the efficient transformation of alcohols into alkyl chlorides, which is promoted by substoichiometric amounts (down to 34 mol %) of inexpensive trichlorotriazine (TCT), is introduced. This is the first example of a TCT‐mediated dihydroxychlorination of an OH‐containing substrate (e.g., alcohols and carboxylic acids) in which all three chlorine atoms of TCT are transferred to the starting material. The consequently enhanced atom economy facilitates a significantly improved waste balance (E‐factors down to 4), cost efficiency, and scalability (>50 g). Furthermore, the current procedure is distinguished by high levels of functional‐group compatibility and stereoselectivity, as only weakly acidic cyanuric acid is released as exclusive byproduct. Finally, a one‐pot protocol for the preparation of amines, azides, ethers, and sulfides enabled the synthesis of the drug rivastigmine with twofold SN2 inversion, which demonstrates the high practical value of the presented method. [ABSTRACT FROM AUTHOR]