Synthesis of diethyl 2-(aryl)vinylphosphonates by the Heck reaction catalysed by well-defined palladium complexes

Preparation of Vinylphosphonates from Ketones Promoted by Tf2O

An efficient triflic anhydride promoted phosphorylation of ketone was disclosed, and vinylphosphorus compounds were prepared under solvent- and metal-free conditions. Both aryl and alkyl ketones could perform smoothly to give vinyl phosphonates in high to excellent yields. In addition, the reaction was easy to carry out and easy to scale up. Mechanistic studies suggested that this transformation might involve nucleophilic vinylic substitution or a nucleophilic addition-elimination mechanism.

Synthesis of P-Substituted 5- and 6-Membered Benzo-Phostams: 2,3-Dihydro-1H-1,2-benzazaphosphole 2-Oxides and 2,3-Tetrahydro-1H-1,2-benzazaphosphinine 2-Oxides

Several approaches were developed for the preparation of phosphorus-substituted 5- and 6-membered benzophostams. Carbodiimide-promoted cyclization of zwitterionic aminophosphinates derived from a nitrobenzene precursor accomplished the cyclization in good yields. Alternatively, a novel copper-catalyzed cross-coupling between a phosphonamide and a bromobenzene precursor produced the heterocycles in moderate to good yields. Three different methods are compared for the synthesis of the P-ethoxy-substituted 5-membered benzophostam.

Copper-Catalyzed Enaminone C(sp2)-N Bond Phosphonation for Stereoselective Synthesis of Alkenylphosphonates

A direct enaminone C-N bond coupling functionalization that generates a new C-P bond using dialkyl phosphonate for the efficient and stereoselective synthesis of (E)-alkenylphosphonates is reported. The reactions toward target products proceed well with a broad scope, disclosing a valuable new synthetic application of enaminones by the interesting C(sp²)-N bond elaboration.

Yttrium and lanthanum bis(phosphine-oxide)methanides: structurally diverse, dynamic, and reactive

Homoleptic yttrium and lanthanum complexes of bis(phosphineoxide) methanides, RE(HPhL)3 and RE2(HMeL)6, promote the first rare-earth mediated Horner-Wittig and acid-base chemistry consistent with multifunctional reactivity (Lewis-acid/Brønstedbase).

Construction of P-Chiral Alkenylphosphine Oxides through Highly Chemo-, Regio-, and Enantioselective Hydrophosphinylation of Alkynes

Alkenylphosphine oxides have a wide spectrum of practical applications. However, chemo-, regio-, and enantiocontrolled construction of this structural motif still constitutes a significant synthetic challenge. Here we show that these compounds can be efficiently accessed by using a palladium/Xiao-Phos catalytic system, which leads to the highly regioselective formation of the anti-Markovnikov adducts through addition of a secondary phosphine oxide to an alkyne. Diverse (hetero)aryl and alkyl alkynes, as well as both terminal and internal alkynes can be employed as substrates. The kinetic resolution process makes it possible to produce alkenylphosphine oxide and recovered secondary phosphine oxides with high ee values. Further transformations of these two P-chiral scaffolds confirm the high practicability and application prospect of our synthetic strategies. Initial mechanistic studies strongly suggested that hydropalladation is likely responsible for the conversion process.

Mono and double Mizoroki–Heck reaction of aryl halides with dialkyl vinylphosphonates using a reusable palladium catalyst under aqueous medium

2-Aryl or 2,2-diaryl vinylphosphonates can be selectively obtained by using aryl halides or dialkylvinylphosphonate as the limiting reagent.

Decarboxylative functionalization of cinnamic acids

Decarboxylative functionalization of α,β-unsaturated carboxylic acids is an emerging area that has been developed significantly in recent years.

Stereoselective synthesis of vinylphosphonates and phosphine oxides via silver-catalyzed phosphorylation of styrenes

An efficient and stereoselective synthesis of vinylphosphonates and phosphine oxides was developed starting from styrenes using AgNO₃ as the catalyst and K₂S₂O₈ as the oxidant. Various vinyl-phosphonates and phosphine oxides were synthesized in good yields with excellent regioselectivity.

Conjugated phosphonic acid modified zinc oxide electron transport layers for improved performance in organic solar cells

Phosphonic acid modification of zinc oxide (ZnO) electron transport layers in inverted P3HT:ICBA solar cells was studied to determine the effect of conjugated linkages between the aromatic and phosphonic acid attachment groups. For example, zinc oxide treated with 2,6-difluorophenylvinylphosphonic acid, having a conjugated vinyl group connecting the aromatic moiety to the phosphonic acid group, showed a 0.78 eV decrease in the effective work function versus unmodified ZnO, whereas nonconjugated 2,6-difluorophenylethylphosphonic acid resulted in a 0.57 eV decrease, as measured by Kelvin probe. This resulted in an average power conversion efficiency of 5.89% for conjugated 2,6-difluorophenyvinylphosphonic acid modified solar cells, an improvement over unmodified (5.24%) and nonconjugated phosphonic acid modified devices (5.64%), indicating the importance of the conjugated linkage.

Experimental and theoretical studies on nickel–zinc-catalyzed cross-coupling of gem-dibromoalkenes with P(O)–H compounds

A new stereoselective one-pot protocol for the preparation of E-alkenyl-phosphorus compounds under catalysis of an inexpensive nickel–zinc catalyst system has been developed, which provides a potential useful method for C–P bond formation.