The Mizoroki‐Heck reaction is one of the most valuable reactions for functionalizing C−C double bonds in the presence of a Pd catalyst. This protocol is suitable for the reaction of a C(sp2)‐halide with a terminal olefin to produce a trans‐1,2‐disubstituted olefin. However, reports of the Mizoroki‐Heck reaction of internal olefins are rare and impractical due to the low reactivity of internal olefins and problems of product diastereoselectivity. In this review, we summarize Mizoroki‐Heck reactions of internal olefins with aryl or alkyl halides to illustrate their reactivities and stereoselectivities.
The direct electrophilic, nucleophilic, and amphiphilic allylations of allylic alcohol by use of a palladium catalyst and organometallic reagents such as organoborane and organozinc has been developed. The phosphine-borane compound works as the effective ligand for palladium-catalyzed direct allylic amination of allylic alcohol. Thus, with secondary amines, the reaction was completed in only 1 h, even at room temperature.
Herein, we report an efficient method for the tertiary alkylation of a ketone by using an α‐bromocarbonyl compound as the tertiary alkyl source in a combined Cu‐organocatalyst system. This dual catalyst system enables the addition of a tertiary alkyl radical to an enamine. Mechanistic studies revealed that the catalytically generated enamine is a key intermediate in the catalytic cycle. The developed method can be used to synthesize substituted 1,4‐dicarbonyl compounds containing quaternary carbons bearing various alkyl chains.
Nucleophilic substitutions, including SN1 and SN2, are classical and reliable reactions, but a serious drawback is their intolerance for both bulky nucleophiles and chiral tertiary alkyl electrophiles for the synthesis of a chiral quaternary carbon center. An SRN1 reaction via a radical species is another conventional method used to carry out substitution reactions of bulky nucleophiles and alkyl halides, but chiral tertiary alkyl electrophiles cannot be used. Therefore, a stereospecific nucleophilic substitution reaction using chiral tertiary alkyl electrophiles and bulky nucleophiles has not yet been well studied. In this paper, we describe the reaction of tertiary alkyl alcohols and non‐chiral or chiral α‐bromocarboxamides as a tertiary alkyl source for the formation of congested ether compounds possessing two different tertiary alkyl groups on the oxygen atom with stereoretention.
In this paper, we report efficient cyanation of various peptides containing the α-bromocarbonyl moiety using a Cucatalyzed radical-based methodology employing zinc cyanide as the cyanide source. Mechanistic studies revealed that in situ formed CuCN was a key intermediate during the catalytic cycle. Our method could be useful for the synthesis of modified peptides containing quaternary carbons.
A variety of π‐electronic ion‐pairing assemblies can be constructed by combining anion complexes of π‐electronic systems and countercations. In this study, a series of anion‐responsive π‐electronic molecules, dipyrrolyldiketone PtII complexes containing a phenylpyridine ligand, were synthesized. The resulting PtII complexes exhibited phosphorescence emission, with higher emission quantum yields (0.30–0.42) and microsecond‐order lifetimes, and solution‐state anion binding, as revealed by our spectroscopic analyses. These PtII complexes displayed solid‐state ion‐pairing assemblies, exhibiting various anion‐binding modes, which derived from pyrrole‐inverted and pyrrole‐non‐inverted conformations, and packing structures, with the contribution of charge‐by‐charge assemblies, which were dependent on the substituents in the PtII complexes and the geometries and electronic states of their countercations.
A light-driven
atom-transfer radical substitution (ATRS) and carboesterification
reaction of alkenes with alkyl halides has been developed using PTH
as the organo-photoredox catalyst. Two types of products were obtained,
depending on the additive and solvent used during the reaction. Primary,
secondary, and tertiary alkyl halides reacted to give the ATRS products.
This protocol has several advantages: it requires mild reaction conditions
and a low catalyst loading and exhibits a broad substrate scope and
good functional group tolerance. Mechanistic studies indicate that
alkyl radicals might be generated as the key intermediates via photocatalysis,
providing a new direction for ATRS reactions.
The abilities of dipyrrolyldiketone boron complexes as hydrogen-bonding donor organocatalysts were examined by the Mannich-type reaction of N-acyl heteroarenium chlorides with 1-methoxy-2-methyl-1-trimethylsiloxy-1-propene, as well as by the classical N-alkylation of amines with trityl chloride under base-free conditions. H NMR examinations of the hydrogen-bonding interaction between the pyrrole NH of the catalyst and the Cl in the N-acyl heteroarenium salt suggested that the activation of N-acyl heteroarenium chlorides occurs through anion binding by the catalyst.
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