No abstract

No abstract

A series of naphthyl-bridged amino-borane derivatives, namely 1-(dimethylamino)-8-naphthylboranes (1, 3, 5, 7) and 5-(dimethylamino)-6-acenaphthylboranes (2, 4, 6, 8, 10, 11), differing in the steric and electronic properties of the boryl moiety, have been synthesized and fully characterized by spectroscopic and crystallographic means. Structural X-ray analysis of the peri-atom displacement and ring torsion angles served to experimentally assess the presence and magnitude of the B-N interactions. The reversible quaternarization of nitrogen has been explored and was found to provide an efficient switch corresponding to different molecular organizations. The electronic characteristics of the nature of B-N interactions were further studied by Natural Bonding Orbital analysis derived from the theoretically calculated electron densities. This real-space bonding indicator discriminates the bonding B-N contact in 5 from the nonbonding in 8, which correlates with the flexibility of the naphthyl scaffold to respond to the Lewis acidity of boron allowing shorter peri interactions. Whereas, the steric shielding imposed by the two mesityl groups, and/or the rigidity of the acenaphthene framework disrupt B-N interaction. Thus, this communication reports on the modulation of the B-N bonding continuum by means of structural tuning leading to a molecular switch, as well as its implications towards revealing FLP reactivities through the isolation of intermediates of a stepwise mechanism.

The synthesis, structure, and reactivity of mixed group 13/group 15 compounds (E13 = B, Al, Ga, In, Tl; E15 = N, P, Sb, Bi) featuring a rigid (ace)naphthalene, biphenylene or (thio)xanthene backbone are discussed in this review.

Acyl chlorides are highly reactive and widely used substrates in catalytic cross-coupling reactions, but so far, site selectivity over other functional groups has remained an issue. In this work, Pd complexes deriving from the phosphine−boranes [i-Pr 2 P(o-C 6 H 4 )] 2 BFXyl and i-Pr 2 P(o-C 6 H 4 )-BFXyl 2 (Fxyl = 3,5-(F 3 C) 2 C 6 H 3 ) were found to preferentially activate acyl chlorides over C−I, C−Br, C−Cl, C−OTf, and C−OTs bonds. The system is amenable to catalysis (Stille and Negishi couplings), providing a simple and efficient means to forge C(O)−C bonds in a site-selective manner and to readily access functionalized ketones. To gain insight into the role and influence of the ambiphilic ligands, key Pd complexes have been authenticated and the reaction profiles have been analyzed by density functional theory (DFT) calculations.

Organometallic catalysis under visible light activation is an emerging field. Activation by photosensitization or by direct light absorption of organometallic complexes can facilitate or trigger elementary steps in a catalytic cycle such as pre-catalyst reduction, oxidative addition, transmetalation and reductive elimination, as well as the ability of generating radical intermediates, widening the structural diversity offered by classical couplings. This perspective aims to highlight key examples of these light-induced or enhanced processes, with an emphasis on the underlying mechanisms involved.

Spectacular progress has recently been achieved in transition metal-catalyzed CÀHb orylation of phosphines as well as directed electrophilic CÀHb orylation. As shown here, P-directed electrophilic borylation provides anew,straightforward,a nd efficient access to phosphine-boranes.I to perates under metal-free conditions and leverages simple,r eadily available substrates.I ti sa pplicable to ab road range of backbones (naphthyl, biphenyl, N-phenylpyrrole,b inaphthyl, benzyl, naphthylmethyl) and gives facile access to various substitution patterns at boron (by varying the boron electrophile or post-derivatizing the borane moiety). NMR monitoring supports the involvement of P-stabilized borenium cations as key intermediates.DFT calculations reveal the existence and stabilizing effect of p-arene/boron interactions in the (biphenyl)(i-Pr) 2 P!BBr 2 + species.

Spectacular progress has recently been achieved in transition metal-catalyzed CÀHb orylation of phosphines as well as directed electrophilic CÀHb orylation. As shown here, P-directed electrophilic borylation provides anew,straightforward,a nd efficient access to phosphine-boranes.I to perates under metal-free conditions and leverages simple,r eadily available substrates.I ti sa pplicable to ab road range of backbones (naphthyl, biphenyl, N-phenylpyrrole,b inaphthyl, benzyl, naphthylmethyl) and gives facile access to various substitution patterns at boron (by varying the boron electrophile or post-derivatizing the borane moiety). NMR monitoring supports the involvement of P-stabilized borenium cations as key intermediates.DFT calculations reveal the existence and stabilizing effect of p-arene/boron interactions in the (biphenyl)(i-Pr) 2 P!BBr 2 + species.