Pd(II)-catalyzed coupling–cyclization reaction of o-ethylnylphenylphosphonamides monoesters with allyl halide

Azaphosphinines and their derivatives

Six-membered heterocycles containing one phosphorus and one nitrogen atom, known as azaphosphinines, have existed in the shadows of their single heteroatom-containing analogues for almost 150 years. Despite this, recent chemistry has seen a rapid increase in publications concerning this uncommon scaffold. Azaphosphinines exist in one of six isomers-there are three possible orientations of the pnictogen atoms and in each of these, the phosphorus is in one of two valences (PIIIvs. PV). This review aims to outline and inform on the synthesis and applications of all six isomers. PV-oxo azaphosphinines are of particular interest to this review as many of the discussed heterocycles either form as the pentavalent species directly or oxidize to this over time. In very recent years the published applications of azaphosphinines have blossomed into subjects spanning several fields of chemistry such as asymmetric catalysis, supramolecular association, cellular imaging, and medicinal chemistry.

Synthesis, photophysical properties, and self-dimerization studies of 2-λ5-phosphaquinolin-2-ones

Rationally designed phosphaquinolinone derivatives containing electron-donating and/or -withdrawing groups are reported, with dimerization constants up to 525 M⁻¹.

Synthesis of P-Stereogenic Benzoazaphosphole 1-Oxides via Alkynylation of P-Stereogenic ortho-Aurated and ortho-Iodo Phosphinic Amides

An efficient methodology for the synthesis of P-stereogenic dihydrobenzoazaphosphole 1-oxides via intramolecular 5-exo-dig alkyne hydroamination promoted by tetrabutylammonium fluoride is herein described. The required chiral o-alkynylphosphinic amide starting materials were prepared in high yields under very mild reaction conditions through alkynylation of P-stereogenic (O^C)-cyclometalated (phosphinic amide)dichlorogold(III) complexes and Sonogashira cross-coupling of ortho-iodo P-stereogenic phosphinic amide.

Palladium-catalyzed domino Heck/intermolecular cross-coupling: efficient synthesis of 4-alkylated isoquinoline derivatives

The first example of a σ-alkylpalladium(ii) intermediate promoting cyclization of alkynes containing a proximate nucleophilic center is presented.

Facile Synthesis and Properties of 2-λ(5)-Phosphaquinolines and 2-λ(5)-Phosphaquinolin-2-ones

Treatment of 2-ethynylanilines with P(OPh)3 gives either 2,2-diphenoxy-2-λ(5)-phosphaquinolines or 2-phenoxy-2-λ(5)-phosphaquinolin-2-ones under transition-metal-free conditions. This reaction offers access to an underexplored heterocycle, which opens up the study of the fundamental nature of the N=P(V) double bond and its potential for delocalization within a cyclic π-electron system. This heterocycle can serve as a carbostyril mimic, with application as a bioisostere for pharmaceuticals based on the 2-quinolinone scaffold. It also holds promise as a new fluorophore, since initial screening reveals quantum yields upwards of 40%, Stokes shifts of 50-150 nm, and emission wavelengths of 380-540 nm. The phosphaquinolin-2-ones possess one of the strongest solution-state dimerization constants for a D-A system (130 M(-1)) owing to the close proximity of a strong acceptor (P=O) and a strong donor (phosphonamidate N-H), which suggests that they might hold promise as new hydrogen-bonding hosts for optoelectronic sensing.