One-Pot Transformation of Ph2P(O)-Protected Ethynes: Deprotection Followed by Transition Metal-Catalyzed Coupling

Ring Opening of Triflates Derived from Benzophospholan-3-one Oxides by Aryl Grignard Reagents as a Route to 2-Ethynylphenyl(diaryl)phosphine Oxides

A new simple method for the synthesis of 2-ethynylphenyl(diaryl)phosphine oxides via ring opening of benzophosphol-3-yl triflates has been developed. This process occurs via nucleophilic attack of a Grignard reagent at the phosphorus center, which results in ring opening and cleavage of a leaving group. The reaction proceeds under mild conditions and, within 15-60 min, leads to a library of previously unavailable 2-ethynylphenylphosphine oxides in yields up to 98%.

Visible-Light-Induced Oxidative C-H Functionalization of Unreactive Cycloalkanes, Alcohols, and Ethers with Alkynylphosphine Oxides into Benzo[b]phosphole Oxides under Photocatalyst-, Metal-, and Base-Free Conditions

We developed the radical cyclization/addition of alkynylphosphine oxides with easily available cycloalkanes, alcohols, and ethers using a visible-light and environmentally friendly synthetic strategy in the absence of photocatalyst at room temperature. This mild and metal- and base-free reaction provided a structurally varied set of significant benzo[b]phosphole oxides through sequential C-H functionalization in an atom-economical manner.

Facile one-pot synthesis of diarylacetylenes from arylaldehydes via an addition-double elimination process

A practical one-pot protocol has been developed to synthesize diarylacetylenes from arylaldehydes by treatment with 1-(arylmethyl)benzotriazoles and LiN(SiMe3)2. The reaction proceeded through imine formation, Mannich-type addition and double elimination to deliver products in up to 99% yields with broad substrate scope. In addition, gram-scale synthesis of 1-bromo-4-(phenylethynyl)benzene has been demonstrated.

Azobisisobutyronitrile-Initiated Oxidative C-H Functionalization of Simple Alcohols with Diaryl(arylethynyl)phosphine Oxides: A Metal-Free Approach toward Hydroxymethyl Benzo[b]phosphole Oxides and 6H-Indeno[2,1-b]phosphindole 5-Oxide Derivatives

The first metal-free and facile radical addition/cyclization of simple alcohols with diaryl(arylethynyl)phosphine oxides has been described with azobisisobutyronitrile as a radical initiator, affording an efficient and one-pot procedure to access a new class of hydroxymethyl benzo[b]phosphole oxides and 6H-indeno[2,1-b]phosphindole 5-oxides for potential application in organic materials via sequential C(sp³)-H/C(sp²)-H functionalization. The method employs easily accessible starting materials and is endowed with high regioselectivity and broad functional-group tolerance.

Synthesis of cyclic phenyl hexayne from Me3Si-/Ph2P(O)-protected ethynes

A practical approach for the synthesis of cyclic phenyl hexayne is demonstrated through a one-pot deprotection/transformation of magnesium acetylide into a copper acetylide/Sonogashira coupling procedure, followed by dephosphination, Hay coupling, desilylation, and Eglinton coupling. This approach avoids tedious synthetic routes and harsh reaction conditions and affords the product in 41% yield.

Aerobic oxidative alkynylation of H-phosphonates and amides: an efficient route for the synthesis of alkynylphosphonates and ynamides using a recyclable Cu–MnO catalyst

We developed a straightforward, atom-economical and scalable route for the synthesis of alkynylphosphonates and ynamides using a reusable Cu–MnO catalyst.

A One-Pot Method for the Synthesis of Phenylalkynyl-Substituted Terminal Alkynes by Deprotection/Stannylation followed by a Migita–Kosugi–Stille coupling

A practical one-pot approach for the synthesis of arylalkynyl-substituted terminal alkynes has been developed through a deprotection/ stannylation of a phenylethynyl phosphine oxide followed by Migita–Kosugi–Stille coupling, avoiding the longer synthetic route involving repeated deprotection/Sonogashira coupling. Other features of this approach include mild reaction conditions, excellent yields, facile isolation of products and wide functional group tolerance.

One-Pot Transformation of Me3Si-/Ph2P(O)-Protected Ethynes to Unsymmetrical Arylethynes

Me3Si-/Ph2P(O)-protected ethynes were successfully transformed to unsymmetrical arylethynes via a one-pot Ph2P(O)-deprotection/ [Pd(dppf)Cl2]-catalysed coupling and one-pot Me3Si-deprotection/Sonogashira coupling under mild conditions and in high yield. Unsymmetrical phenylethynes, unsymmetrical extended phenylene ethynylenes and unsymmetrical anthrylethynes were successfully synthesised in good to excellent yields.

Direct synthesis of alkynylphosphonates from alkynes and phosphite esters catalyzed by Cu/Cu2O nanoparticles supported on Nb2O5

A new, recyclable and efficient copper catalyst for cross-couplings of alkynes and phosphite esters has been disclosed, in which the synergistic effects of Nb₂O₅ on the catalyst are found owing to its strong Lewis acid sites.

TBAI-catalyzed oxidative C–H functionalization: a new route to benzo[b]phosphole oxides

The first metal-free, efficient TBAI-catalyzed radical addition/cyclization of diaryl(arylethynyl)phosphine oxides with toluene derivatives has been developed, affording a general, one-step approach to structurally sophisticated benzo[b]phosphole oxides via sequential C–H functionalization along with the formation of two new C–C bonds.

Visible light-mediated gold-catalysed carbon(sp2)-carbon(sp) cross-coupling

A new method for the alkynylation of aryldiazonium salts with TMS-alkynes via dual gold and photoredox catalysis is described.

A dual photoredox and gold-catalysed cross-coupling reaction of alkynyltrimethylsilanes and aryldiazonium tetrafluoroborates is described. The reaction proceeds through visible-light mediated oxidative addition of aryldiazoniums, transmetalation of alkynyltrimethylsilanes and aryl–alkynyl reductive elimination. Exclusive selectivity for silyl-substituted alkynes is observed, with no reactivity observed for terminal alkynes.

Remarkable electron-withdrawing effect of the Ph2P(O)-ethynyl group: Ph2P(O)-ethynyl-substituted aryl halides and copper acetylides for tailor-made Sonogashira couplings

Ph₂P(O)-ethynylphenyl bromide showed higher reactivity in Sonogashira couplings than phenylethynylphenyl bromide because of the electron-withdrawing nature of the Ph₂P(O) group.