Visible light promoted copper-catalyzed Markovnikov hydration of alkynes at room temperature

A new and efficient method for the hydration of alkynes to the corresponding ketones was successfully developed. The hydration process proceeds smoothly at room temperature with 1% mol of CuCl as catalyst under visible light irradiation. This protocol is applicable to various alkynes, including aromatic alkynes, polycyclic aromatic and heterocyclic aromatic excellent regioselectivity in good to excellent yields.     

One-pot synthetic routes to multiply substituted indene derivatives by hydrolysis of zirconocene-mediated intermolecular coupling reactions of aromatic ketones and alkynes

Two one-pot multicomponent synthetic methods for highly substituted indenes are described. The intermolecular coupling of aromatic ketones with alkynes on low-valent zirconocene species generates oxazirconacyclopentenes, which upon hydrolysis with 20% HCl for 3 h afforded indene derivatives in good to excellent yields. Similarly, the pair-selective coupling of two identical or different alkynes bearing at least one aromatic substituent formed zirconacyclopentadienes. Quenching of the reaction mixture with concentrated H(2)SO(4) also results in the formation of highly substituted indenes in high yields.     

Heterogeneous intermolecular hydroamination of terminal alkynes with aromatic amines

Heterogeneous intermolecular hydroamination of alkynes with aromatic amines using inexpensive transition metal-exchanged clay catalysts was investigated. Reaction of terminal alkynes with aromatic amines gave higher yields of imines.     

Tertiary Carbinamine Synthesis by Rhodium‐Catalyzed [3+2] Annulation of N‐Unsubstituted Aromatic Ketimines and Alkynes

A convenient and waste‐free synthesis of indene‐based tertiary carbinamines by rhodium‐catalyzed imine/alkyne [3+2] annulation is described. Under the optimized conditions of 0.5–2.5 mol % [{(cod)Rh(OH)}₂] (cod=1,5‐cyclooctadiene) catalyst, 1,3‐bis(diphenylphosphanyl)propane (DPPP) ligand, in toluene at 120 °C, N‐unsubstituted aromatic ketimines and internal alkynes were coupled in a 1:1 ratio to form tertiary 1H‐inden‐1‐amines in good yields and with high selectivities over isoquinoline products. A plausible catalytic cycle involves sequential imine‐directed aromatic C? H bond activation, alkyne insertion, and a rare example of intramolecular ketimine insertion into a Rh^I–alkenyl linkage.     

Hydration of aromatic terminal alkynes catalyzed by sulfonated condensed polynuclear aromatic (S-COPNA) resin in water

Hydration of aromatic terminal alkynes in the presence of a catalytic amount of sulfonated condensed polynuclear aromatic (S-COPNA) resin in water gave the corresponding methyl ketones in good yields. On the other hand, aliphatic terminal alkynes did not react at all under the employed conditions. Chemoselective hydration of aromatic terminal alkyne in the presence of aliphatic terminal alkyne catalyzed by S-COPNA resin was carried out.     

Enantioselective zinc/BINOL-catalysed alkynylation of aldimines generated in situ from α-amido sulfones

Chiral nonracemic N-Cbz-protected propargylic amines have been prepared by the addition of terminal alkynes to imines generated in situ from α-amido sulfones in the presence of diethylzinc and BINOL-type ligands as catalysts. The reactions give good yields and high enantioselectivities (ee values up to 95?%) for a good number of aromatic and heteroaromatic α-amido sulfones and alkynes.     

Sequential catalytic process: synthesis of quinoline derivatives by AuCl3/CuBr-catalyzed three-component reaction of aldehydes, amines, and alkynes

A sequential catalytic process has been developed based on gold-catalyzed nucleophilic addition of terminal alkynes to imines, and gold-catalyzed intramolecular reaction of aromatic ring to alkynes. This one-pot reaction of aldehydes, amines, and alkynes gives quinoline derivatives in good yields.     

Indium-Promoted Allylation of Alkynes with Allylic Alcohols: Highly Regioselective Synthesis of Halogen-Substituted 1,4-Dienes

Indium-promoted allylation of alkynes by direct use of allyl alcohols as the allylating agents has been developed under mild conditions, in which a wide range of allylic alcohols and alkynes (both aromatic and aliphatic alkynes) could be tolerated, and the corresponding halogen-substituted 1,4-dienes were obtained in moderate to excellent yields.     

Enantioselective addition of terminal alkynes to N-(diphenylphosphinoyl)imines catalyzed by Zn–BINOL complexes

Chiral nonracemic N-(diphenylphosphinoyl)-protected propargylic amines have been prepared by addition of terminal alkynes to N-(diphenylphosphinoyl)aldimines in the presence of dimethylzinc and 3,3′-dibromo-BINOL as catalyst. The reaction works with a variety of aromatic and heteroaromatic aldimines and with different alkynes, providing the expected products in generally good yields and enantiomeric excesses (up to 96%).     

Enantioselective Zinc/BINOL‐Catalysed Alkynylation of Aldimines Generated in Situ from α‐Amido Sulfones

Chiral nonracemic N‐Cbz‐protected propargylic amines have been prepared by the addition of terminal alkynes to imines generated in situ from α‐amido sulfones in the presence of diethylzinc and BINOL‐type ligands as catalysts. The reactions give good yields and high enantioselectivities (ee values up to 95 %) for a good number of aromatic and heteroaromatic α‐amido sulfones and alkynes.     

Sonogashira Coupling Reaction with Palladium Powder and Potassium Fluoride in Methanol

A Sonogashira coupling reaction of aromatic halides with terminal alkynes in the presence of palladium powder,potassium fluoride,cuprous iodide and triphenylphosphine in methanol,giving the corresponding coupling products aryl alkynes in good to excellent yiekls,was investigated.     

Au(I)-catalyzed highly efficient intermolecular hydroamination of alkynes

[reaction: see text] Addition of aniline derivatives to aromatic and aliphatic alkynes proceeds efficiently in the presence of a gold(I) catalyst (0.01-1.0 mol %) to afford ketimines in good yields     

Reactivity of cyclic sulfamidates towards lithium acetylides: synthesis of alkynylated amines

A synthetically useful level of reactivity of cyclic sulfamidates toward acetylides is described. Ring-opening reactions of a structurally diverse set of 1,2- and 1,3-cyclic sulfamidates with a range of lithium acetylides from aliphatic, cyclic, aromatic, heteroaromatic, and functionalized alkynes proceed smoothly in a regioselective manner to give the corresponding N-sulfate intermediates. Hydrolysis of these intermediates under acidic conditions furnishes the alkynylated amines in yields ranging from 29% to 98%. The scope of the acetylenic substitution reaction with the structural variations in both the cyclic sulfamidates and alkynes is briefly examined.     

A Facile and Practical Process for the Synthesis of Polysubstituted Furans from Alkynes Using Atmospheric Oxygen as a Terminal Oxidant

We present here a facile and practical procedure for the synthesis of tetrasubstituted furans from alkynes catalyzed by palladium acetate together with cupric acetate in acetic acid, using atmospheric oxygen as a terminal oxidant. Various internal aromatic alkynes afforded the target furans in satisfactory yield.     

1,7-Octadiene-Assisted Tandem Multicomponent Cross-Enyne Metathesis (CEYM)-Diels-Alder Reactions: A Useful Alternative to Mori's Conditions

The use of 1,7-octadiene as an in situ source of ethylene led us to develop a novel multicomponent tandem cross-enyne metathesis (CEYM)-Diels-Alder reaction. The process can be considered a relay metathesis, in which the ethylene liberated in the ring-closing metathesis (RCM) of 1,7-octadiene initiates the tandem sequence. Aliphatic, aromatic, and fluorinated alkynes and several dienophiles are compatible with the process, which is particularly efficient with aromatic alkynes. This methodology constitutes a useful variant of Mori's conditions in CEYM-related reactions.     

Palladium-catalyzed benzannulation from alkynes and allylic compounds

Various alkynes reacted with allyl tosylates in the presence of palladium catalysts, giving polysubstituted benzenes with good to high regioselectivity. Pentasubstituted and trisubstituted benzenes were readily prepared by reaction of internal alkynes and terminal alkynes, respectively. The combination of allyl alcohols and p-toluenesulfonic anhydride could be utilized in place of isolated allyl tosylates. The cyclization of diynes with allyl tosylate afforded bicyclic compounds containing an aromatic ring.     

A dramatic effect of aryloxo ligands on the titanium-catalyzed hydroamination of alkynes

The aryloxotitanium complex 1 is a highly chemo- and regioselective catalyst for intermolecular hydroamination of terminal alkynes. Branched imines are obtained in good to excellent yield (up to 99%) with various primary aromatic and aliphatic amines. [reaction: see text]     

Synthesis of 1,4-dithiins from pentathiepins

Fused aromatic and heterocyclic 1,2,3,4,5-pentathiepins react with triphenylphosphine and alkynes bearing electron-withdrawing groups to give the corresponding 1,4-dithiins in high yields. Unsymmetrical alkynes add regioselectively to afford products in agreement with the electron distribution in a proposed reaction intermediate. A mechanism for these reactions is proposed.     

Iridium as a general catalyst for the decarbonylative addition of aldehydes to alkynes

A general catalytic system for the decarbonylative addition reaction of aldehydes with alkynes is developed by using an iridium catalyst system. Both aromatic and aliphatic aldehydes reacted with terminal alkynes efficiently to give the corresponding olefination products in high yields and up to 11:1 E/Z selectivity.     

1,7‐Octadiene‐Assisted Tandem Multicomponent Cross‐Enyne Metathesis (CEYM)‐Diels–Alder Reactions: A Useful Alternative to Mori’s Conditions

The use of 1,7‐octadiene as an in situ source of ethylene led us to develop a novel multicomponent tandem cross‐enyne metathesis (CEYM)‐Diels–Alder reaction. The process can be considered a relay metathesis, in which the ethylene liberated in the ring‐closing metathesis (RCM) of 1,7‐octadiene initiates the tandem sequence. Aliphatic, aromatic, and fluorinated alkynes and several dienophiles are compatible with the process, which is particularly efficient with aromatic alkynes. This methodology constitutes a useful variant of Mori’s conditions in CEYM‐related reactions.