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α‐Silylalkylamines and α‐borylalkylamines are versatile synthetic intermediates and attractive scaffolds found in pharmaceutical drugs and agrochemicals. Despite great progress on synthetic methods for preparation of α‐silylalkylamines or α‐borylalkylamines, there are no general strategies for preparation of α‐boryl‐α‐silylalkylamines and the reactivity has not been explored. Here we report deoxygenative geminal silylboration of amides using silylboronates in the presence of alkoxide base catalyst, producing α‐boryl‐α‐silylalkylamines. The silicon and boron groups in α‐boryl‐α‐silylalkylamines are found to be utilized to chemoselective transformations, such as protonation and alkylation. This protocol serves various α‐silylalkylamines and α‐borylalkylamines from readily available amides. [ABSTRACT FROM AUTHOR]

α‐Silylalkylamines and α‐borylalkylamines are versatile synthetic intermediates and attractive scaffolds found in pharmaceutical drugs and agrochemicals. Despite great progress on synthetic methods for preparation of α‐silylalkylamines or α‐borylalkylamines, there are no general strategies for preparation of α‐boryl‐α‐silylalkylamines and the reactivity has not been explored. Here we report deoxygenative geminal silylboration of amides using silylboronates in the presence of alkoxide base catalyst, producing α‐boryl‐α‐silylalkylamines. The silicon and boron groups in α‐boryl‐α‐silylalkylamines are found to be utilized to chemoselective transformations, such as protonation and alkylation. This protocol serves various α‐silylalkylamines and α‐borylalkylamines from readily available amides. [ABSTRACT FROM AUTHOR]

A quadruple N‐heterocyclic carbene/cobalt/photoredox/Brønsted base catalysis to realize branch‐selective hydroacylation of styrenes with aromatic and aliphatic aldehydes is demonstrated. This protocol allows access to branched ketones from readily available materials in an atom‐economical manner. The quadruple catalysis can transfer a formyl hydrogen of aldehydes as a hydrogen radical equivalent onto the terminal carbon of an alkene by controlled electron and proton transfers. [ABSTRACT FROM AUTHOR]

Over the past century, significant progress in semipinacol rearrangement involving 1,2-migration of α-hydroxy carbocations has been made in the areas of catalysis and total synthesis of natural products. To access the α-hydroxy carbocation intermediate, conventional acid-mediated or electrochemical approaches have been employed. However, the photochemical semipinacol rearrangement has been underdeveloped. Herein, we report the organophotoredox-catalyzed semipinacol rearrangement via radical-polar crossover (RPC). A phenothiazine-based organophotoredox catalyst facilitates the generation of an α-hydroxy non-benzylic alkyl radical followed by oxidation to the corresponding carbocation, which can be exploited to undergo the semipinacol rearrangement. As a result, the photochemical approach enables decarboxylative semipinacol rearrangement of β-hydroxycarboxylic acid derivatives and alkylative semipinacol type rearrangement of allyl alcohols with carbon electrophiles, producing α-quaternary or α-tertiary carbonyls bearing sp3-rich scaffolds. Although electrochemical semipinacol rearrangements have been reported, a complementary photochemical route has yet to be developed. Here the authors report an organophotoredox-catalyzed semipinacol rearrangement via radical-polar crossover. [ABSTRACT FROM AUTHOR]

A catalytic reductive cross‐coupling between arylaldehydes and aryl electrophiles using a silylboronate as a terminal reductant is described. The reaction involves a copper‐catalyzed silylboration of aldehydes affording the O‐borylated α‐silyl alcohols followed by a nucleophilic aromatic substitution reaction with aryl electrophiles. This protocol offers a new opportunity to access 1,1‐diarylmethanol derivatives without rare metals or highly basic organometallic reagents. [ABSTRACT FROM AUTHOR]

We developed an organophotoredox‐catalyzed reaction for N‐alkylation of sulfonamides with aliphatic carboxylic acid‐derived redox active esters as alkylating reagents. Under mild and transition metal‐free conditions, a series of functionalized N‐alkylated sulfonamides were prepared. This protocol also enabled the functionalization of pharmaceutical drugs bearing a sulfonamide or carboxylic acid moiety. This radical‐mediated process allowed the assembly of three components including sulfonamides, redox active esters, and alkenes to yield complex sulfonamides in a one‐pot manner. [ABSTRACT FROM AUTHOR]

There have been significant advancements in radical reactions using organocatalysts in modern organic synthesis. Recently, NHC-catalyzed radical reactions initiated by single electron transfer processes have been actively studied. However, the reported examples have been limited to catalysis mediated by alkyl radicals. In this article, the NHC organocatalysis mediated by aryl radicals has been achieved. The enolate form of the Breslow intermediate derived from an aldehyde and thiazolium-type NHC in the presence of a base undergoes single electron transfer to an aryl iodide, providing an aryl radical. The catalytically generated aryl radical could be exploited as an arylating reagent for radical relay-type arylacylation of styrenes and as a hydrogen atom abstraction reagent for α-amino C(sp3)–H acylation of secondary amides. Use of aryl halides as coupling precursors typically occurs through transition metal catalysis and/or photoredox chemistry, which requires some combination of light, metals, and oxidants or reductants. Here, the authors show a method to generate aryl radicals from halides using only an NHC organocatalyst. [ABSTRACT FROM AUTHOR]

A reductive cross‐coupling reaction between aromatic aldehydes and arylnitriles using a copper catalyst and a silylboronate as a reductant is reported. This protocol represents an unprecedented approach to the chemoselective synthesis of α‐hydroxy ketones by electrophile–electrophile cross‐coupling. [ABSTRACT FROM AUTHOR]

The transition‐metal‐free cross‐coupling of alkyl or aryl electrophiles by using tertiary benzylic organoboronates is reported. This reaction involves the generation of tertiary alkyl anions from organoboronates in the presence of an alkoxide base and then their substitution reactions. This protocol allows the simple and efficient construction of quaternary carbon centers. [ABSTRACT FROM AUTHOR]

The transition‐metal‐free cross‐coupling of alkyl or aryl electrophiles by using tertiary benzylic organoboronates is reported. This reaction involves the generation of tertiary alkyl anions from organoboronates in the presence of an alkoxide base and then their substitution reactions. This protocol allows the simple and efficient construction of quaternary carbon centers. [ABSTRACT FROM AUTHOR]

In this communication, we report a chiral copper/NHC-catalyzed reaction between aromatic aldehydes and propargylic phosphates using a silylboronate, providing enantioenriched chiral α-allenic alcohols with complete regioselectivity and moderate to high enantioselectivity. The reaction pathway involves the catalytic formation of a nucleophilic α-alkoxylalkylcopper(I) species from aldehydes followed by its SN2′ type substitution reaction with propargylic phosphates. [ABSTRACT FROM AUTHOR]

Dehydrative allylation between widely available aldehydes and allylic alcohols to afford β,γ‐unsaturated ketones was enabled by a synergistic merger of a thiazolium N‐heterocyclic carbene catalyst and a palladium‐bisphosphine catalyst. Dehydrative allylation between widely available aldehydes and allylic alcohols to afford β,γ‐unsaturated ketones was enabled by a synergistic merger of a thiazolium N‐heterocyclic carbene catalyst and a palladium‐bisphosphine catalyst. [ABSTRACT FROM AUTHOR]

Abstract: Trialkylphosphine organocatalysis has enabled the regioselective anti‐carboboration of alkynoates with 9‐BBN‐based 1,1‐diborylalkanes to produce secondary allylboranes with β‐alkoxycarbonyl and γ‐boryl substituents. The utility of the densely functionalized allylboranes was demonstrated by the highly diastereoselective allylation of N‐(trimethylsilyl)aldimines to produce homoallylamines containing tertiary allylborane and acrylate moieties. [ABSTRACT FROM AUTHOR]

Abstract: Trialkylphosphine organocatalysis has enabled the regioselective anti‐carboboration of alkynoates with 9‐BBN‐based 1,1‐diborylalkanes to produce secondary allylboranes with β‐alkoxycarbonyl and γ‐boryl substituents. The utility of the densely functionalized allylboranes was demonstrated by the highly diastereoselective allylation of N‐(trimethylsilyl)aldimines to produce homoallylamines containing tertiary allylborane and acrylate moieties. [ABSTRACT FROM AUTHOR]

A synergistic action of a thiazolium N‐heterocyclic carbene catalyst and a palladium–bisphosphine catalyst has enabled the allylation between aldehydes acyl anions and allylic amines to afford β,γ‐unsaturated ketones, which are versatile synthetic intermediates for organic synthesis. [ABSTRACT FROM AUTHOR]

A method for the synthesis of 1,1-diborylalkenes through a Brønsted base catalyzed reaction between terminal alkynes and bis(pinacolato)diboron has been developed. The procedure allows direct synthesis of functionalized 1,1-diborylalkenes from various terminal alkynes including propiolates, propiolamides, and 2-ethynylazoles. [ABSTRACT FROM AUTHOR]

A method for the synthesis of 1,1-diborylalkenes through a Brønsted base catalyzed reaction between terminal alkynes and bis(pinacolato)diboron has been developed. The procedure allows direct synthesis of functionalized 1,1-diborylalkenes from various terminal alkynes including propiolates, propiolamides, and 2-ethynylazoles. [ABSTRACT FROM AUTHOR]

The scope of the copper-catalyzed coupling reactions between organoboron compounds and allylic phosphates is expanded significantly by employing triphenylphosphine as a ligand for copper, allowing the use of secondary alkylboron compounds. The reaction proceeds with complete γ- E-selectivity and preferential 1,3- syn stereoselectivity. The reaction of γ-silicon-substituted allylic phosphates affords enantioenriched α-stereogenic allylsilanes. [ABSTRACT FROM AUTHOR]

Ein vielseitiger Weg zu trisubstituierten Alkenylstannanen wird vorgestellt. Die Alkyl ‐ und Sn ‐ Einheiten werden am β ‐ bzw. α ‐ Kohlenstoffatom von Alkinoaten in einer formalen syn ‐ Addition mit vollständiger Regioselektivität eingeführt (siehe Schema). Dabei wird eine Vielzahl an funktionellen Gruppen im Alkylboran und im Alkinoat toleriert. [ABSTRACT FROM AUTHOR]

A versatile route to trisubstituted alkenylstannanes is presented. The alkyl and Sn moieties were introduced at the β and α carbon atoms of alkynoates, respectively, in a formal syn addition mode with complete regioselectivity (see scheme). A variety of functional groups were tolerated in the alkylboranes and alkynoates. [ABSTRACT FROM AUTHOR]

A copper-catalyzed γ-selective allyl-alkyl coupling between γ-silylated allylic phosphates and alkylboron compounds (alkyl- 9-BBN, prepared by hydroboration of alkenes with 9-BBN-H) produced allylsilanes. The reaction tolerated various functional groups in both the alkylboranes and the allylic phosphates, and afforded functionalized allylsilanes. [ABSTRACT FROM AUTHOR]

N-Heterocyclic carbene (NHC) catalysis can access umpolung reactivity of carbonyl compounds as acyl anions, enolates and homoenolates. Considerable progress has been made in asymmetric transformation by the introduction of chirality to the NHC scaffold. However, the single catalyst system has limitations in chemo-, regio- and stereoselectivity. A solution to these problems has recently emerged with the synergistic combination of NHC catalysis and metal catalysis. A number of NHC/metal combinations have been found not only to improve reactivity and stereoselectivity, but also to enable access to unprecedented transformations. This paper highlights examples of successful asymmetric NHC/metal cooperative catalysis. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue is the group of Hirohisa Ohmiya and co‐workers at Kanazawa University. The image depicts cooperative action between a thiazolium N‐heterocyclic carbene organocatalyst and a palladium catalyst. Read the full text of the article at 10.1002/chem.201805955. "[our] process is highly advantageous compared with the conventional allylation between acyl metal reagents and activated allylic electrophiles in terms of step and atom economy." Read more about the story behind the cover in the Cover Profile and about the research itself on page 724 ff. (DOI: 10.1002/chem.201805955). [ABSTRACT FROM AUTHOR]

Synergistic cooperation of thiazolium N‐heterocyclic carbene catalyst and a palladium catalyst enabled the dehydrative direct allylation between aldehydes and allylic alcohols to produce β,γ‐unsaturated ketones. The cover picture depicts a similar relationship between anemone fish and sea anemone living cooperatively in their natural environment. More information can be found in the Communication by H. Ohmiya et al. on page 724. [ABSTRACT FROM AUTHOR]