Bending the planar trigonal boron center of triphenylborane by connecting its aryl rings with carbon or phosphorus linkers gave access to a series 9-boratriptycene derivatives unprecedented structures and reactivities. NMR spectroscopy X-ray diffraction Lewis adducts these non-planar acids weak base revealed particularly strong covalent bond formation. The first adduct trivalent compounds Tf2 N- anion illustrates unrivaled acidity species. Increasing pyramidalization using cationic...

This short review highlights recent advances in amide reductions. The last two years have witnessed important developments with milestones reached catalytic hydrogenations and hydrosilylations. While metal-catalyzed processes still focus tremendous efforts from the scientific community, methodologies based on metal-free hydrosilylation of amides definitively joined competition. 1 Introduction 2 Recent Use Stoichiometric Reducing Reagents 3 Hydrogenations 4 Hydrosilylations 5 Conclusion Outlook

A highly bent triarylborane, 9-boratriptycene, was generated in solution by selective protodeboronation of the corresponding tetra-aryl boron ate complex with strong Brønsted acid HNTf2 . The iptycene core confers enhanced Lewis acidity to making it unique terms structure and reactivity. We studied stereoelectronic properties 9-boratriptycene quantifying its association small N- O-centered bases, as well sterically hindered phosphines. resultant adducts exhibited structural, spectroscopic,...

A reduction of various aryl, alkyl, and α,β-unsaturated amides with phenylsilane, catalysed by a borinic acid, is reported. The unprecedented reaction was carried out under very mild conditions led to useful amines. Furthermore, the tolerates variety functional groups. Initial investigations implicated that an intermediate diarylhydroborane involved in mechanism.

The rational design of a geometrically constrained boron Lewis superacid featuring exceptional structure and reactivity is disclosed. It enabled the formation non-classical electron deficient B-H-B type bonding, which was supported by spectroscopic structural parameters as well computational studies. Taming pyramidal acid electrophilicity through weak coordinating anion dissociation series highly challenging chemical transformations, such Csp2 -H Csp3 activation under frustrated pair regime...

The synthesis, properties and structural requirements for atropisomerism at the C−B bond in boron Lewis acids such as triarylboranes have been understudied so far. We report first series of atropisomeric constituted a naphthyl rotor dihydro‐9‐bora‐anthracenyl stator subunits, connected by stereogenic axis. Through systematic crystallographic, kinetic, photophysical quantum chemical studies, mechanisms, rates barriers diastereomerization enantiomerization were determined. orthogonal...

The synthesis, properties and structural requirements for atropisomerism at the C−B bond in boron Lewis acids such as triarylboranes have been understudied so far. We report first series of atropisomeric constituted a naphthyl rotor dihydro‐9‐bora‐anthracenyl stator subunits, connected by stereogenic axis. Through systematic crystallographic, kinetic, photophysical quantum chemical studies, mechanisms, rates barriers diastereomerization enantiomerization were determined. orthogonal...

Phenylsilane was reevaluated as a useful coupling reagent for amide synthesis. At room temperature, wide range of amides and peptides were obtained in good to excellent yields (up 99 %). For the first time, Weinreb synthesis mediated by hydrosilane also documented. Comparative experiments with various acetoxysilanes suggested involvement phenyl‐triacyloxysilane. From this mechanistic study, silicon tetraacetate shown an efficient amine acylating agent.

Abstract Bending the planar trigonal boron center of triphenylborane by connecting its aryl rings with carbon or phosphorus linkers gave access to a series 9‐boratriptycene derivatives unprecedented structures and reactivities. NMR spectroscopy X‐ray diffraction Lewis adducts these non‐planar acids weak base revealed particularly strong covalent bond formation. The first adduct trivalent compounds Tf 2 N − anion illustrates unrivaled acidity species. Increasing pyramidalization using...

Abstract A highly bent triarylborane, 9‐boratriptycene, was generated in solution by selective protodeboronation of the corresponding tetra‐aryl boron ate complex with strong Brønsted acid HNTf 2 . The iptycene core confers enhanced Lewis acidity to making it unique terms structure and reactivity. We studied stereoelectronic properties 9‐boratriptycene quantifying its association small N‐ O‐centered bases, as well sterically hindered phosphines. resultant adducts exhibited structural,...

Abstract The general reduction of phosphine oxides, sulfoxides, and amine N ‐oxides was achieved by combining bis(2‐chlorophenyl)borinic acid with phenylsilane. reaction shown to tolerate a wide range substrates could be performed under mild conditions, only 2.5 mol % the easily synthesized catalyst. Mechanistic investigations pointed key borohydride as real catalyst at precatalyst.

Study of the intramolecular aza-Michael addition reaction from an aminofluorovinylsulfone opens a new route for synthesis pyrrolidine derivatives. An unexpected diastereoselective cyclization was observed, leading preferentially to anti-N-benzylpyrrolidine sulfone. The resulting sulfone reacted with aldehydes access β-substituted α-fluoroalkenyl pyrrolidines in one step.

Although boron Lewis acids commonly adopt a trigonal planar geometry, number of compounds in which the trivalent atom is located pyramidal environment have been described. This review will highlight recent developments chemistry and applications non-planar acids, including series triarylboranes derived from triptycene core. A thorough analysis properties influence pyramidalization on their stereoelectronic reactivities presented based theoretical experimental studies. 1 Non-planar...

4‐Fluoro‐2‐chlorophenylborinic acid acts as a precatalyst in the presence of phenylsilane for facile reduction ketones, aldehydes and imines. Notably, synergistic mediation tertiary amine was found essential to trigger silicon boron hydride transfer generate key amine–diarylhydroborane Lewis complex.

Abstract The activation or heterolytic splitting of methane, a challenging substrate usually restricted to transition metals, has so far proven elusive in experimental frustrated Lewis pair (FLP) chemistry. In this article, we demonstrate, using density functional theory (DFT), that 1‐aza‐9‐boratriptycene is conceptually simple intramolecular FLP for the methane. Systematic comparison with other systems allows gain insight into their reactivity thermodynamics and kinetics methane are...

Abstract The rational design of a geometrically constrained boron Lewis superacid featuring exceptional structure and reactivity is disclosed. It enabled the formation non‐classical electron deficient B−H−B type bonding, which was supported by spectroscopic structural parameters as well computational studies. Taming pyramidal acid electrophilicity through weak coordinating anion dissociation series highly challenging chemical transformations, such Csp 2 −H 3 activation under frustrated pair...

Abstract The association of pyridine and 2,4,6‐trimethylpyridine (collidine) with a pyramidal triarylborane belonging to the 9‐boratriptycene family is investigated by NMR spectroscopy X‐ray diffraction analysis. Despite large size ortho‐disubstituted collidine Lewis base steric hindrance boron superacid used (9‐boratriptycene‐10‐sulfonium), superacidity at its atom enabling formation B‐N bond resulting in very stabe adduct. Single‐ crystal analysis revealed an exceptional deformation moiety...

Abstract A non-planar triarylborane and a new member of the boratriptycene family bearing selenium atom in bridgehead position triptycene scaffold was generated isolated as boron-‘ate’ complex paired with weakly coordinating anion. With similar electronegativity while possessing longer radius respect to sulfur, introduction atom, form selenenium moiety, at allows very precise modification pyramidalization boron environment. Experimental computational evaluation Lewis acidity this derivative...

Isolation and characterization of highly reactive intermediates are crucial to understand the nature chemical reactivity. Accordingly, reactivity weakly coordinating anions (WCA), usually used stabilized cationic super electrophiles fundamental interest. When a variety WCA known form stable σ-complexes with proton, inducing Brønsted acidity, bis-coordinated weak-coordinated much more elusive considered as long-sought species. In this work, chemistry borylated sulfate, triflimidate triflate...

Abstract Three synthetic methods towards semi‐planar triarylboranes with two aryl rings connected by a methylene bridge have been developed. The fine‐tuning of their stereoelectronic properties and Lewis acidities was achieved introducing fluorine, methyl, methoxy, n ‐butyl phenyl groups either at exocyclic or bridged rings. X‐ray diffraction analysis quantum‐chemical calculations provided quantitative information on the structural distortion experienced near planar hydro‐boraanthracene...

The organocatalyzed Mannich coupling of cyclic carboxaldehydes allowed the concise and simple preparation spirocyclic aminolactones. Their conversion into pharmaceutically relevant spiro[4.5]cyclic spiro[4.6]cyclic 3-aminopyrrolidines is also described.

Abstract Starting from aminofluorosulfones a novel access to N‐benzylpyrrolidine sulfones is elaborated.