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Under a dioxygen atmosphere, benzylphosphonates and related phosphoryl compounds can readily produce the corresponding trans-stilbenes in high yields with high selectivity upon treatment with bases. Various functional groups were tolerable under the reaction conditions. [ABSTRACT FROM AUTHOR]

A silver-free palladium-catalyzed dehydrogenative phosphorylation of terminal alkynes with hydrogen phosphine oxides has been developed. Both aromatic and aliphatic terminal alkynes including those bearing functional groups coupled readily with hydrogen phosphine oxides, producing the corresponding value-added alkynylphosphine oxides in good to excellent yields. This reaction could be easily conducted at gram scales (10 mmol) without any decrease of the reaction efficiency, showing highly potential synthetic value in organic synthesis. A plausible Pd(0)/Pd(II) mechanism is proposed. [ABSTRACT FROM AUTHOR]

A Pd-catalyzed dehydrogenative phosphorylation of thiols is developed. A variety of thiols dehydrogenatively couple readily with all three kinds of P(O)--H compounds, i.e., H-phosphonates, H-phosphinates, and secondary phosphine oxides, providing a general access to the valuable phosphorothioates including the P-chiral compounds. A plausible mechanism is proposed. [ABSTRACT FROM AUTHOR]

Themechanism of the palladium-catalyzed cross dehydrogenativecoupling of P(O)–H compounds with terminal alkynes was studied.Successive ligand-exchange reactions of Pd(OAc)2with ahydrogen phosphoryl compound and a terminal alkyne take place readilyto replace the two acetates on palladium, producing the corresponding(phosphoryl) (alkynyl)palladium complexes, which upon heating decomposedto the corresponding alkynylphosphorus compound. It is also confirmedthat in the stoichiometric reactions of the complexes, the configurationat phosphorus is retained. On the basis of these stoichiometric reactions,an efficient synthesis of P-chiral alkynylphosphorylcompounds via palladium-catalyzed stereoselective cross dehydrogenativecoupling of P-chiral P(O)–H compounds withterminal alkynes was developed. The key palladium complexes and thestereochemistry of the chiral phosphorus compounds are all unambiguouslydetermined by single-crystal X-ray analysis. [ABSTRACT FROM AUTHOR]

In this account, we summarize our recent work on the preparation of optically active H-phosphinates and their stereospecific transformations, including regio- and stereospecific additions, nucleophilic substitutions with organolithiums and Grignard reagents, halogenation with copper(II) chloride, and dehydrogenative couplings with heteroatom- hydrogen bonds. These reactions provide efficient ways for the synthesis of valuable, optically active, P-stereogenic, organophosphorus compounds from relatively easily prepared, enantiomerically pure, menthyl hydrogen phosphinates. The applications of optically active Hphosphinates in catalytic asymmetric hydrogenations are also discussed. 1 Optically Pure Menthyl Hydrogen Phosphinates: Easily Accessible P-Stereogenic Starting Materials 2 Optically Pure Menthyl Hydrogen Phosphinates as Starting Materials for the Synthesis of P-Chiral Compounds 2.1 Stereospecific Additions 2.1.1 Additions to Alkynes 2.1.2 Addition to Alkenes 2.1.3 Addition to p-Quinones 2.1.4 Additions to Ketones or Aldehydes 2.2 Stereospecific Nucleophilic Substitution by Organolithiums or Grignard Reagents 2.3 Stereospecific Halogenation with Copper(II) Chloride 2.4 Stereospecific Cross-Dehydrogenative Coupling with Nucleophiles (Amines, Alcohols, Thiols, etc.) 2.5 Stereospecific Cross-Coupling with C-X Bonds 3 Asymmetric Catalytic Hydrogenation Reactions with Optically Pure Menthyl Hydrogen Phosphinates as Ligands 4 Conclusion [ABSTRACT FROM AUTHOR]

The Ni-catalyzed direct C–H/C–Ocross couplings ofbenzylic alcohol derivatives with fluorobenzenes and heteroarenesare disclosed. This transformation provides a straightforward andefficient method for the synthesis of these valuable heteroatom-containingcompounds. [ABSTRACT FROM AUTHOR]

The first Ni-catalyzed C-O/P-H cross-coupling producing organophosphorus compounds is disclosed. This method features wide generality in regard to both C-O and P-H compounds: for C-O compounds, the readily available alcohol derivatives of aryl, alkenyl, benzyl, and allyl are applicable, and for P-H compounds, both >PV(O)H compounds (secondary phosphine oxide, H-phosphinate, and H-phosphonate) and hydrogen phosphines (>PIIIH) can be used as the substrates. Thus, a variety of valuable C(sp²)-P and C(sp³)-P compounds can be readily obtained in good to excellent yields by this new strategy. [ABSTRACT FROM AUTHOR]

A metal-free regioselective hydrobromination of alkynes has been developed to provide the Markovnikov-type vinyl bromides in good yields using dibromomethane/N,N-dimethylaniline as in-situ 'HBr' source. This protocol also represents an elegant example of the activation of sp² CH and CBr bonds in one pot, in which 'HBr' is generated and transferred under mild metal-free conditions. D-incorporated experiments were employed to investigate the reaction mechanism and a plausible reaction path was proposed. [ABSTRACT FROM AUTHOR]

A facile, highly stereo- and regioselective hydrometalation of alkynes generating alkenylmetal complex is disclosed for the first time from a reaction of alkyne, carboxylic acid, and a zerovalent group 10 transition metal complex M(PEt3)4 (M = Ni, Pd, Pt). A mechanistic study showed that the hydrometalation does not proceed via the reaction of alkyne with a hydridometal generated by the protonation of a carboxylic acid with Pt(PEt3)4, but proceeds via a reaction of an alkyne coordinate metal complex with the acid. This finding clarifies the long proposed reaction mechanism that operates via the generation of an alkenylpalladium intermediate and subsequent transformation of this complex in a variety of reactions catalyzed by a combination of Brφnsted acid and Pd(0) complex. This finding also leads to the disclosure of an unprecedented reduction of alkynes with formic acid that can selectively produce cis-, trans-alkenes and alkanes by slightly tuning the conditions. [ABSTRACT FROM AUTHOR]

An efficient nickel-catalyzed phosphorylation of phenol derivatives with P(O)-H compounds via C-O/P-H cross-coupling is described. Under the reaction conditions, various phenyl pivalates coupled readily with hydrogen phosphoryl compounds to afford the corresponding coupling products aryl phosphonates and aryl phosphine oxides in good to high yields. [ABSTRACT FROM AUTHOR]

Catalyst-free and selective C-N bond functionalization has been achieved through three-component coupling of amines, dihalomethane, and >P(O)H species. This reaction takes place stereospecifically with retention of configuration at phosphorus, which can produce various new optically active phosphorus analogues of α-amino acids. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed decarbonylative alkynylation of amides via C-N bond activation is developed. Compared with the reported Ni/Cu catalyzed reaction, which only proceeded well with silylacetylenes, this transformation was also applicable to both aromatic and aliphatic terminal alkynes, including those bearing functional groups, and thus provided a general and straightforward access to diverse internal alkynes. [ABSTRACT FROM AUTHOR]

An efficient oxidative aminooxyarylation of alkenes under a transition-metal-free condition was described. Under the reaction conditions, N-hydroxyphthalimide (NHPI) reacted readily with N-arylacrylamides to produce cyclic products via a radical C-H functionalization process, achieving both C-O and C-C bonds formation in one pot. This reaction provided a facile access to the valuable aminooxylated oxindoles. The benzylic and a-methylene C(sp³)-H bonds were also aminooxylated under the reaction conditions. [ABSTRACT FROM AUTHOR]

A simple and environmentally benign method was developed for the synthesis of chalcones in high to excellent yields by a phosphorous acid promoted alkyne-aldehyde hydration-condensation in an oil/water two-phase system. The method is the first efficient protocol for the preparation of chalcones that is mediated by a simple Brønsted acid in a two-phase system. [ABSTRACT FROM AUTHOR]