The intermolecular radical functionalization of arenes with aryl and alkyl H-phosphinate esters, as well as diphenylphosphine oxide and H-phosphonate diesters, is described. The novel catalytic Mn^II/excess Mn^IV system is a convenient and inexpensive solution to directly convert C_sp2H into CP bonds. The reaction can be employed to functionalize P-stereogenic H-phosphinates since it is stereospecific. With monosubstituted aromatics, the selectivity for para-substitution increases in the order (RO)₂P(O)H<R¹P(O)(OR)H<Ph₂P(O)H, a trend that may be explained by steric effects.

Two generally applicable systems have been developed for the cross-coupling of P(O)H compounds with C_sp2X and related partners. Palladium catalysis using a ligand/additive combination, typically either xantphos/ethylene glycol or 1,1′-bis(diphenylphosphino)ferrocene/1,2-dimethoxyethane, with diisopropylethylamine as the base, proved to be generally useful for the synthesis of numerous PC containing compounds. Routinely, 2 mol% of catalyst are employed (less than half the amount typically employed in most other literature reports). In most cases, excellent results are obtained with a variety of electrophiles (RX, where R=alkenyl, allyl, alkynyl, etc.). The full account of our studies is disclosed, including tandem hydrophosphinylation/coupling and coupling/coupling for doubly catalytic phosphorus-carbon bond formation. The methodology compares favorably with any existing literature report. The use of an additive appears to be a generally useful strategy to control the reactivity of phosphinylidene compounds.

A process for the conversion of hypophosphorous acid (H₃PO₂, HPA) and alcohols into various H-phosphonate diesters [(RO)₂P(O)H] is described. The new reaction provides a missing bridge between HPA and important H-phosphonates, completely avoiding the use of PCl₃. Nickel chloride or nickel on silica catalyze the oxidative phosphorylation of alkyl phosphinates with various alcohols or water. The reaction is atom economic and avoids the formation of waste products. The previous need for both chlorine and base is completely avoided.

The first metal-catalyzed hydrophosphinylation of unsaturated hydrocarbons with H-phosphinic acids is described. A strategy to activate the PH bond through control of the tautomeric equilibrium using ethylene glycol is described. The reactions also avoid chromatographic purification.

H-Phosphinates obtained through various methodologies are protected directly by the reaction with triethyl orthoacetate. The resulting products can be manipulated easily, andvarious synthetic reactions are presented. For example, application to the synthesis of aspartate transcarbamoylase (ATCase) or kynureninase inhibitors are illustrated. Other reactions, such as Sharpless' asymmetric dihydroxylation, or Grubbs' olefin cross-metathesis are also demonstrated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

The reactions of phosphinylidene-containing compounds with unactivated unsaturated hydrocarbons are reviewed. The review is organized by phosphorus-containing functional group types. Free-radical and metal-catalyzed additions of R¹R²P(O)H to alkenes, alkynes, and related compounds deliver functionalized organophosphorus compounds RP(O)R¹R², including H-phosphinates, phosphinates, tertiary phosphane oxides, and phosphonates. The review covers the literature up to February 2008.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Benzylic alcohols cross-couple directly with concentrated H₃PO₂ by using Pd/xantphos (1 or 2 mol-%). Depending on the substrate, DMF at 110 °C or t-AmOH at reflux with a Dean–Stark trap can be used. A broad range of benzylic alcohols react successfully to give moderate to good yields of the products. The preparation of other organophosphorus compounds (phosphinic and phosphonic acids) is also demonstrated. Asymmetric reaction with (R)-1-(2-naphthyl)ethanol provids the corresponding H-phosphinic acid in 77 % ee. The methodology provides a green, PCl₃-free route to benzylic-H-phosphinic acids.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Five new metal pyridylphosphonate polymers have been prepared, fully characterized, and their room-temperature luminescence probed. The reaction of (2-pyridyl)phosphonic acid (2pypo) with ZnX₂ (X = Br, Cl) afforded two-dimensional polymers [Zn(X)(2pypo)]_n {X = Cl = (1), X = Br = (2)}, which feature cyclic 12-membered Zn–O–P cores that are interlinked by bridged oxygen atoms from the phosphonate moiety. From the room–temperature, aqueous reactions of 2pypo and the corresponding metal salts, the one-dimensional polymers [Cd(μ-Cl)₂(2pypo)]_n (3) and [Hg(2pypo)]_n (4) were isolated in moderate yield. The one-dimensional structure of 3 is supported through bridging chlorides and two η2-phosphonate oxygen atoms, while 4 is a highly symmetrical polymer that exhibits pyridyl nitrogen coordination to the mercury center and uses two μ₂-oxygen atoms to polymerize. Reaction of silver triflate (CF₃SO₃Ag) with 2pypo afforded a crystalline silver polymer that displays a zig-zag arrangement of silver atoms with argentophilic interactions and that is stablized through bridged triflate and phosphonate moieties. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)