The migrations of different groups to the metal–carbene center of RhII‐stabilized iminocarbenes that were derived from N‐sulfonyl triazoles are discussed (see scheme). The reactivity of these ...Rh‐iminocabenes can be tuned easily by variation of substituents on the parent triazole.
A general and efficient NH insertion reaction of rhodium pyridyl carbenes derived from pyridotriazoles was developed. Various NH‐containing compounds, including amides, anilines, enamines, and ...aliphatic amines, smoothly underwent the NH insertion reaction to afford 2‐picolylamine derivatives. The developed transformation was further utilized in a facile one‐pot synthesis of imidazo1,5‐apyridines.
Insert here: A general and efficient NH insertion reaction of rhodium pyridyl carbenes derived from pyridotriazoles was developed. Various NH‐containing compounds, including amides, anilines, enamines, and aliphatic amines, smoothly underwent the NH insertion reaction to afford 2‐picolylamine derivatives. The developed transformation was further utilized in a facile one‐pot synthesis of imidazo1,5‐apyridines. esp=α,α,α′,α′‐tetramethyl‐1,3‐benzenedipropionic acid, Ts=4‐toluenesulfonyl.
Two methods for remote aromatic CH oxygenation reactions, have been developed. Method 1, the Cu‐catalyzed oxygenation reaction, is highly efficient for cyclization of electron‐neutral and ...electron‐rich biaryl carboxylic acids into 3,4‐benzocoumarins. Method 2, the K2S2O8‐mediated oxygenation reaction, is more general and practical for cyclization of substrates with electron‐donating and ‐withdrawing groups (see scheme).
And the world is your oyster…︁ Sequential halogenation/oxygenation reactions of 2‐diisopropylsilylpyrimidine‐substituted arenes provide a general and efficient synthesis of substituted ...meta‐halophenols from simple aryl iodides (see scheme; Piv=pivaloyl). The products are poised to undergo diverse CC, CN, and CO bond‐forming reactions that enable the transformation of their framework and the introduction of valuable functionalities.
A modifiable or removable pyrimidyldiisopropylsilyl (PyrDipSi) directing group for double-fold symmetrical and unsymmetrical C–H functionalizations of arenes has been developed. The PyrDipSi ...directing group can be efficiently installed on arenes via the Rh-catalyzed cross-coupling reaction of an aryl iodide with 2-(diisopropylsilyl)pyrimidine (PyrDipSiH). This directing group allows for a highly efficient Pd-catalyzed C–H oxygenation and halogenation reaction of various arenes to produce a variety of symmetrically and unsymmetrically substituted arenes, including resorcinols, m-halophenols, and 1,3-dihaloarenes. Importantly, the PyrDipSi group can easily be removed or efficiently converted into valuable functionalities, which opens an access to densely substituted arene products from aryl iodides. Hence, the generality of this strategy was highlighted by the synthesis of up to hexasubstituted arene products from simple iodobenzene via iterative C–H functionalization reactions.
The efficient Pd-catalyzed double-fold C–H oxygenation of arenes into resorcinols using the newly developed 2-pyrimidyldiisopropylsilyl (PyrDipSi) directing group is described. Its use allows for the ...sequential introduction of OAc and OPiv groups in a one-pot manner to produce orthogonally protected resorcinol derivatives. The PyrDipSi group is superior to the previously developed 2-pyridyldiisopropylsilyl (PyDipSi) group, as it is efficient for monooxygenation of ortho-substituted arenes. Notably, the PyrDipSi group can be easily installed into arene molecules and can be easily removed or modified after the oxygenation reaction.
The ubiquitous nature of C-H bonds in organic molecules makes them attractive as a target for rapid complexity generation, but brings with it the problem of achieving selective reactions. In ...developing new methodologies for C-H functionalization, alkenes are an attractive starting material because of their abundance and low cost. Here we describe the conversion of 1-alkenes into 1,4-diols. The method involves the installation of a new Si,N-type chelating auxiliary group on the alkene followed by iridium-catalysed C-H silylation of an unactivated δ-C(sp(3))-H bond to produce a silolane intermediate. Oxidation of the C-Si bonds affords a 1,4-diol. The method is demonstrated to have broad scope and good functional group compatibility by application to the selective 1,4-oxygenation of several natural products and derivatives.
A novel mode of reactivity for the diazo group, the 1,3‐addition of a nucleophile and an electrophile to the diazo group, has been realized in the intramolecular aminoalkylation of ...β‐amino‐α‐diazoesters to form tetrasubstituted 1,2,3‐triazolines. The reaction exhibited a broad scope, good functional group tolerance, and excellent diastereoselectivity. In addition, a new Au‐catalyzed intramolecular transannulation reaction of the obtained propargyl triazolines to give pyrroles has been discovered.
Tetrasubstituted 1,2,3‐triazolines were synthesized from β‐amino‐α‐diazoesters. This aminoalkylation proceeds through the unusual 1,3‐addition of a nucleophile and an electrophile to the diazo group. The reactions exhibit a broad scope and good functional group tolerance as well as excellent diastereoselectivity.
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