Synthesis of P-Stereogenic Phosphine Oxides via Nickel-Catalyzed Asymmetric Cross-Coupling of Secondary Phosphine Oxides with Alkenyl and Aryl Bromides.

A general and mild nickel-catalyzed enantioselective C(sp2 )-P cross-coupling for synthesizing P-stereogenic phosphine oxides has been developed. The asymmetric alkenylation/arylation of racemic secondary phosphine oxides with alkenyl/aryl bromides generated P-stereogenic phosphine oxides with high yields and enantioselectivities. Various functional groups were tolerated, and the applications of this method were demonstrated through late-stage functionalization and product transformations.

Nickel-Catalyzed Asymmetric Synthesis of P-Stereogenic Phosphanyl Hydrazine Building Blocks.

Catalytic asymmetric methods for the synthesis of synthetically versatile P-stereogenic building blocks offer an efficient and practical approach for the diversity-oriented preparation of P-chiral phosphorus compounds. Herein, we report the first nickel-catalyzed synthesis of P-stereogenic secondary aminophosphine-boranes by the asymmetric addition of primary phosphines to azo compounds. We further demonstrate that the P-H and P-N bonds on these phosphanyl hydrazine building blocks can be reacted sequentially and stereospecifically to access various P-stereogenic compounds with structural diversity.

Secondary Phosphine Sulfide-Enabled Iridium-Catalyzed Asymmetric Allylic Substitution.

An iridium-catalyzed asymmetric synthesis of branched allylic phosphine compounds under mild conditions is reported. Products bearing various functional groups can be synthesized with excellent stereoselectivity (up to 99.9 % ee) and regioselectivity. The employment of phosphine sulfides with relatively low deactivation capacity against metal catalysts is crucial for the success of this reaction.

Asymmetric Synthesis of P-Stereogenic Secondary Phosphine-Boranes by an Unsymmetric Bisphosphine Pincer-Nickel Complex.

The first highly enantioselective catalytic synthesis of P-stereogenic secondary phosphine-boranes was realized by the asymmetric addition of primary phosphine to electron-deficient alkenes with a newly developed unsymmetric bisphosphine (PCP') pincer-nickel complex. Various P-stereogenic secondary phosphine-boranes were obtained in 57-92% yields with up to 99% ee and >20:1 dr. The follow-up alkylation upon P-C bond formation with alkyl halides provided a practical way to access P-chiral compounds with diverse functional groups.

Cobalt-Catalysed Asymmetric Addition and Alkylation of Secondary Phosphine Oxides for the Synthesis of P-Stereogenic Compounds.

The catalytic asymmetric synthesis of P-chiral phosphorus compounds is an important way to construct P-chiral ligands. Herein, we report a new strategy that adopts the pyridinyl moiety as the coordinating group in the cobalt-catalysed asymmetric nucleophilic addition/alkylation of secondary phosphine oxides. A series of tertiary phosphine oxides were generated with up to 99 % yield and 99.5 % ee, and with broad functional-group tolerance. Mechanistic studies reveal that (R)-secondary phosphine oxides preferentially interact with the cobalt catalysts to produce P-stereogenic compounds.

Palladium-Catalyzed C-H Alkenylation of Arenes with Alkynes: Stereoselective Synthesis of Vinyl Chlorides via a 1,4-Chlorine Migration.

A directing group-free, ligand-promoted palladium-catalyzed C-H arylation of internal alkynes with simple arenes was developed. Alkenyl chlorides resulting from a 1,4-chlorine migration or trisubstituted alkenes were produced in moderate to good yields depending on the type of alkyne.

Palladium-catalyzed enantioselective C-H arylation for the synthesis of P-stereogenic compounds.

A palladium-catalyzed enantioselective C-H arylation of N-(o-bromoaryl)-diarylphosphinic amides is described for the synthesis of phosphorus compounds bearing a P-stereogenic center. The method provides good enantioselectivities and high yields. The products were readily transformed into P-chiral biphenyl monophosphine ligands.

Silver-mediated oxidative C-H/P-H functionalization: an efficient route for the synthesis of benzo[b]phosphole oxides.

A Ag-mediated C-H/P-H functionalization reaction of arylphosphine oxides with internal alkynes was described for the direct preparation of benzo[b]phosphole oxides with a high yield. An unusual aryl migration on the P-atom derived from a C-P bond cleavage and a new C-P bond formation was also observed and demonstrated to proceed via the radical process.

Photoinduced Copper-Catalyzed C(sp3)-P Bond Formation by Coupling of Secondary Phosphines with N-(Acyloxy)phthalimides and N-Fluorocarboxamides.

A photoinduced copper-catalyzed C(sp3)-P bond formation has been developed by using N-(acyloxy)phthalimides as radical precursors and secondary phosphine boranes as coupling partners. A variety of alkyl carboxylic acid derivatives can be readily transformed into the corresponding phosphines with high reaction efficiency and structural diversity. Besides, utilizing the 1,5-HAT of the N-centered radical process, the δ C(sp3)-H bond can be coupled with secondary phosphines, which provides a novel method for the regioselective formation of C(sp3)-P bonds.

Copper-catalyzed asymmetric C(sp2)-H arylation for the synthesis of P- and axially chiral phosphorus compounds.

Transition metal-catalyzed C-H bond functionalization is an important method in organic synthesis, but the development of methods that are lower cost and have a less environmental impact is desirable. Here, a Cu-catalyzed asymmetric C(sp2)-H arylation is reported. With diaryliodonium salts as arylating reagents, a range of ortho-arylated P-chiral phosphonic diamides were obtained in moderate to excellent yields with high enantioselectivities (up to 92% ee). Meanwhile, enantioselective C-3 arylation of diarylphosphine oxide indoles was also realized under similar conditions to construct axial chirality.

Palladium-catalyzed asymmetric addition of diarylphosphines to enones toward the synthesis of chiral phosphines.

An asymmetric addition of diarylphosphines to beta-substituted enones under mild conditions using a chiral pincer-palladium catalyst has been developed for the synthesis of chiral phosphines with excellent stereoselectivity (up to 99% ee).

Asymmetric construction of quaternary α-nitro amides by palladium-catalyzed C(sp3)-H arylation.

Pd-Catalyzed enantioselective C(sp3)-H arylation of N-(o-Br-aryl) anilides has been disclosed, and quaternary α-nitro amides were constructed with up to 98% ee. The presence of the nitro group on the substrate enables the progress of the reaction and the ready transformation of the product to optically active quaternary amino acid derivatives.

Site-Tunable Csp3-H Bonds Functionalization by Visible-Light-Induced Radical Translocation of N-Alkoxyphthalimides.

Site-tunable functionalization of C(sp3)-H bonds has been accomplished through radical translocation and cross-coupling. Upon irradiation with visible light, copper-based photocatalyst [Cu(Xantphos)(dmp)]BF4 enabled cross-coupling of N-alkoxyphthalimides with amino acid esters or amino acids to provide δ-C(sp3)-H alkylated alcohols (31 examples, up to 92% yield) with additive BNDHP or α-C(sp3)-H alkylated alcohols (18 examples, up to 86% yield) with additive DABCO in a highly regioselective fashion.

Syntheses of Benzofuranoquinolines and Analogues via Photoinduced Acceptorless Dehydrogenative Annulation of o-Phenylfuranylpyridines.

A strategy for the syntheses of benzofuranoquinolines and its analogues via the irradiation of o-phenylfuranyl/thienylpyridines/pyrimidines in DCM with UV light at rt under an argon atmosphere is described. The mechanism of this reaction through the process of 6π-electrocyclization, [1,5]-hydrogen shift, and 1,3-eneamine tautomerism leading to H2 evolution was elucidated. Notably, the syntheses of cis-8b-methyl-8b,13a-dihydrobenzo[f]benzofuro[3,2-h]quinolone via the photoinduced rearrangement of 2-(3-methylbenzofuran-2-yl)-3-phenylpyridine relevant to the mechanism of this reaction highlights the importance of the developed methodology.

Rhodium-catalyzed isomerization of unactivated alkynes to 1,3-dienes.

A rhodium/binap complex has been found to effectively catalyze the isomerization of unactivated internal alkynes to the corresponding 1,3-dienes in the presence of an azomethine imine as the reaction promoter.

Palladium-Catalyzed Asymmetric Arylation of C(sp(3))-H Bonds of Aliphatic Amides: Controlling Enantioselectivity Using Chiral Phosphoric Amides/Acids.

Enantioselective arylation of secondary ß-C(sp(3))-H bonds of 8-aminoquinoline amides was realized with a palladium catalyst. Chiral phosphoric amides and acids were used for the first time to control the stereoselectivity at the C-H bond cleavage step in the C-H activation reactions.

Synthesis of novel axially chiral Rh-NHC complexes derived from BINAM and application in the enantioselective hydrosilylation of methyl ketones.

Novel axially chiral Rh N-heterocyclic carbene complexes were prepared from axially dissymmetric 1,1'-binaphthalenyl-2,2'-diamine and applied in the Rh-catalyzed enantioselective hydrosilylation of methyl ketones. The corresponding sec-alcohols can be obtained in high yields with good to excellent ee.

Palladium-catalyzed asymmetric 1,6-addition of diarylphosphines to α,ß,γ,δ-unsaturated sulfonic esters: controlling regioselectivity by rational selection of electron-withdrawing groups.

Palladium-catalyzed asymmetric 1,6-addition of diarylphosphines to electron-deficient dienes was developed through rational selection of electron-withdrawing groups on the dienes. Various chiral allylic phosphine derivatives were synthesized in good yields with high enantioselectivity (up to 96% ee).

2-Hydroxy-1,10-phenanthroline vs 1,10-phenanthroline: significant ligand acceleration effects in the palladium-catalyzed oxidative Heck reaction of arenes.

A series of bidentate monoanionic nitrogen ligands were designed and applied in the Pd-catalyzed oxidative Heck reaction of arenes with alkenes. Significant ligand-accelerated effects were observed, and direct C-H functionalized products were formed in high yields with meta-selectivity.

Palladium-catalyzed asymmetric addition of diarylphosphines to α,ß-unsaturated sulfonic esters for the synthesis of chiral phosphine sulfonate compounds.

Highly stereoselective addition of diarylphosphines to α,ß-unsaturated sulfonic esters catalyzed through a PCP pincer-Pd complex is developed to synthesize chiral phosphine sulfonic esters with excellent enantioselectivity (up to 99.5% ee). The transformation of the chiral adduct into a useful palladium phosphine sulfonate complex is also demonstrated.