AN EFFICIENT SYNTHESIS OF PROPARGYLIC PHOSPHONIUM SALTS

Alkylated propargyl bromides react with phosphiaes in acidic tetrahydrofuran solution to give propargylic phosphonium salts in good yield.

Stereoselective synthesis of substituted 1,3-dienes from propargylic esters: electrophilic-metal or redox catalysis?

1,3-Diene architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials but also serve as versatile building blocks to furnish important functionalized molecules in synthetic chemistry due to conjugated repeating C=C units. Accordingly, various strategies to access substituted 1,3-dienes in a stereoselective manner have been developed. However, chemo-, regio-and stereoselective synthesis of highly substituted 1,3-dienes still remains elusive and challenging. Readily available propargylic esters have emerged as an appealing class of synthetic intermediates for accessing functionalized 1,3-dienes, especially challenging tri-or tetrasubstituted variants, via transition-metal catalysis, including electrophilic metal and redox neutral catalysis. This review, for the first time, systematically highlights recent advances in transitionmetal catalyzed synthesis of substituted 1,3-dienes from propargylic esters, discusses the mechanisms and synthetic utilities, and gives the remaining challenges and potential opportunities in this field.

CuCl-Catalyzed Aerobic Oxidation of Allylic and Propargylic Alcohols to Aldehydes or Ketones with 1 ： 1 Combination of Phenanthroline and Bipyridine as the Ligandst

We developed a modified protocol for the oxidation of 2,3-allenyl alcohols using CuCI with l ： 1 combination of phenanthroline and bipyridine as the catalyst. To further investigate the applicability of this system, other types of alcohols such as allylic and propargylic alcohols have been tested： we found that both allylic and propargylic alcohols may be oxidized to the corresponding aldehydes or ketones using molecular oxygen in air as the oxidant with moderate to excellent yields.

Regio- and （E）-Stereoselective Triborylation of Propargylic Carbonates

An efficient synthesis of （E）-alken-1,2,3-triboronates form readily available propargylic carbonates is described. The reaction enjoys excellent regio- and E-selectivity and many synthetically useful functional groups can be tolerated. Based on mechanistic studies, a two-step mechanism via 1,2-allenyl boronate intermediate is proposed.

Enantioselective carboxylative cyclization of propargylic alcohol with carbon dioxide under mild conditions

An enantioselective carboxylative cyclization of propargylic alcohols and CO2 was realized under mild conditions,based on a kinetic resolution strategy,which enabled the synthesis of chiral cyclic carbonates and propargylic alcohols with promising yield and enantioselectivity simultaneously.

Brønsted acid-catalyzed 1,6-hydrophosphination of propargylic para-quinone methides and aza-para-quinone methides for the rapid construction of phosphorus-substituted quaternary carbon centers

An intriguing Brønsted acid-catalyzed 1,6-hydrophosphination of in situ generated propargylic para-quinone methides(p-QMs)and aza-para-quinone methides(aza-p-QMs)with H-phosphorus oxides via dehydration/1,6-addition under ultrasonic irradiation is described.This methodology provides a rapid and green approach for the construction of diarylmethyl phosphorus oxides bearing phosphorus-substituted quaternary carbon centers in high yields(up to 98%yield)within merely 5min.This environmentally benign protocol represents a unique example of 1,6-conjugate additions of propargylic p-QMs and aza-p-QMs for site-selective C-P bond formation in an operationally simple and atom-economical manner.The use of readily available Brønsted acid catalyst,operationally simplicity,high yields,and high atom economy make this protocol very facile,practical,easily scaled-up and environmentally friendly.

Copper-catalyzed asymmetric propargylic substitution of anthrones and propargylic esters

Anthrones are key structural motifs in many natural products, bioactive compounds and pharmaceutical chemicals. Earth-abundant-metal-catalyzed asymmetric functionalization of anthrones has not proved to be viable. Herein, we disclosed a highly enantioselective propargylic substitution of anthrones with propargylic esters using copper salts with chiral N, N, P-ligand. This strategy is amenable to a broad range of substrates, uses readily available starting materials, provides excellent yields with remarkable enantioselectivity under mild conditions, and enables attractive products diversification routes.

Palladium(0)catalyzed reactions of propargylic carbonates and dialkyl cycloalkanone-α,α-dicarboxylates

Propargylic carbonates reacted with dialkyl cycloalkanone-α,α′-dicarboxylates under the catalysis of Pd(0)complex to give bicyclic compounds in high yields.The two electron-withdrawing groups at α and α′positions of cycloalkanone rings are essential for the annulation reaction.

Preparation of phenyl substituted propargylic alcohol dicobalt hexacarbonyls and their reactions with active methylene compounds in the presence of acid

Eight new complexes with the formula [PhC_2C(OH)R^2R^2]Co_2(CO)_6 were prepared from phenyl substituted propargylic alcohols and dicobalt octacarbonyl.The reactions of these propargylio alcohol complexes with active methylene compounds,2,4-pentanedione or ethyl acetoacetate,in the presnce of an acid,HBF_4(40％)+P_2O_5(in excess)or BF_3·Et_2O,at room temperature in dichlorome- thane were investigated.From the 1-alkyl substituted tertiary propargylic alcohol complexes,three new conjugated ene-yne complexes produced by intramolecular dehydration reaction were isolated in high yields(82—95％).On the other hand,four new alkylated complexes were obtained with satisfactory yields(44—66％)from the secondary propargylic alcohol complexes.The influence of other acids,phosphorus pentoxide and polyphosphoric acid,on both dehydration reaction and alkylated reaction was also studied.

Stereoselective Synthesis of δd-Selanyl Allylic Alcohols by Hydrozirconation of Propargyl Selenides

Hydrozirconation of propargyl selenides afford (E)-3-selanyl vinylzirconocenes chlorides 2. Intermediates 2 reacted with aldehydes to obtain d-selanyl allylic alcohols.

PHOTOPOLYMERIZATION OF PROPARGYL ACETATE WITH MICHLER’S KETONE AS PHOTOINITIATOR

Photopolymerization of propargyl acetate (PAT) with Michler's ketone (MK) asphotoinitiator in benzene has been investigated for the first time. Some features of the PATphotopolymerization with MK as photoinitiator is described.

Practical synthesis allenyl and homopropargyl alcohol through Cp_2TiCl_2 -Mg with propargyl alcohol derivatives

Reaction of Cp2TiCl2-Mg synthetic equivalent of practical Ti(II) reagent with propargyl alcohol derivatives affords allenyl titanium compounds in good yields.thus, providing an efficient and practical methods for synthesis of both allenyl and homopropargyl alcohols by the successive treatment with aldehydes and ketones.

Regioselective Propargylation of Aldehydes with Propargyl Bromide Mediated by Sn-In in Aqueous Media under Microwave Irradiation

Tin-indium were employed in the propargylations of various aldehydes with propargyl bromide in the presence of SnCl2 and C6H5（CH3）3NBr under microwave irradiation to afford the corresponding homopropargyl alcohols exclusively in high yields. All the reactions were completed smoothly in predominantly aqueous media in 200 seconds only.

Synthesis and Structure of an Octopus-like Octapropargyl Tetra-iso-butyl-resorcin[4]arene

Treatment of tetra-iso-butyl-resorcin[4]arene 1 with propargyl bromide in the presence of K2CO3 as base gave an octopus-like octapropargyl tetra-iso-butyl-resorcin[4]arene 2 （C68H72O8, Mr = 1017.26） in a quantitative yield. Single-crystal structure of 2 was determined by X-ray crystallography. 2 crystallizes in the monoclinic system, space group P21/n with a =13.3247（6）, b = 24.7929（11）, c = 19.1810（9）A°, β = 109.272（1）°, V= 5981.5（5） A°^3, Dc = 1.130g/cm^3,μ = 0.073 mm^-1, F（000） = 2176 and Z = 4. Overall structure of 2 reveals an octopus-like resorcinarene with eight propargyl groups in different directions. The resorcinarene adopts the boat conformation where the iso-butyl residues act as four-legged piano stool. The two opposite aryl rings of the macrocyclic framework are almost coplanar, and the two others facing each other are perpendicular to this plane.

A Novel Thin Film Resistive Humidity Sensor Based on SolubleConjugated Polymer:(propionic acid)-co-(propargyl alcohol)

A novel soluble conjugated copolymer (propionic acid)-co-(propargyl alcohol) (PA-co-OHP) has been synthesized for the first time using a new palladium acetylide catalyst Pd(PPh3)(2)(C=CC(CH3)(2)OH)(2)(PPB). Thin film resistive humidity sensor based oil the copolymer doped with HClO4 was prepared. The impedance of the sensor changed from 10(3)similar to 10(7) Omega in 95%similar to 30%RH, and the response of that is very quick (<6 sec.). Preliminary results show the copolymer is a promising humidity sensitive material.

A New Humidity-Sensitive Material Based on PPBT Prepared with Palladium Complex Catalyst

Soluble Poly(propargyl benzoate) (PPBT) with pi -conjugated structure was synthesized using a novel bis(triphenylphosphine)-bisacetylide palladium complex catalyst [Pd(PPh3)(2)(C equivalent to CCH2OOCPh)(2)] (PPB). An interdigital gold electrode was covered by screen printing films of doped PPBT (DPPBT) to prepare a resistance-type humidity sensor, which exhibits electrical response towards relative humidity (RH%) variations in the range 11%-96%. PPBT shows promise as a new humidity-sensitive material.

Arylation of Allyl, Cinnamyl and Propargyl Bromide with Triarylbismuth Catalyed by Pd(0)

Allyl and cinnamyl and propargyl bromide reacted under mild conditions with triarylbismuth under catalysis by Pd(O) to give 3-arylpropenes, 1, 3-diarylpropenes and arylpropadienes in modest to excellent yields.

Evaluation of Propargyl Alcohol as a Corrosion Inhibitor for Duplex Stainless Steel in Hydrochloric Acid

ASTM A182 F51 duplex stainless steel with a 50:50 ratio of austenite to ferrite microstructure is a material used in mechanical engineering.Its uses include the manufacturing of equipment and components subject to acidification or acid stimulation for oil and gas industries.During acid stimulation or acidification,hydrochloric acid(HCl)solution with concentrations ranging from 5%to 28%(by volume)is injected into the limestone(CaCO3)and dolomite(CaCO3·MgCO3)reservoir rock to restore permeability and consequently increase oil well productivity.Therefore,it is important to use a corrosion inhibitor,such as propargyl alcohol,to prevent or inhibit the aggressive attack of HCl on duplex stainless steel.The present study evaluates the corrosion resistance of ASTM A182 F51 stainless steel using gravimetric(mass loss)and electrochemical(polarization)tests.Studies were completed with and without the addition of 500 and 1,000 mg/L propargyl alcohol in HCl solutions with concentrations of 10%and 15%(by volume)at temperatures of 25,40 and 55°C.The good protection by propargyl alcohol of duplex steel immersed in HCl is observed.

Divergent synthesis of chiral amines via Ni-catalyzed chemo-and enantioselective hydrogenation of alkynone imines

Ligand-mediated nickel-catalyzed asymmetric hydrogenation of alkynone imines has been achieved. By using Ni(OAc)_2·4H_2O/(S,S)-Ph-BPE complex as a catalyst, the chemo-and enantioselective hydrogenation of alkynone imines occurred efficiently to afford chiral propargyl amines with high yields and excellent enantioselectivities(up to 99% yield, >99% ee), leaving the readily reducible alkynyl group intact. Both the C=N and C≡C bonds of alkynone imines were hydrogenated efficiently in the presence of Ni(OAc)_2·4H_2O and Josiphos SL-J011-1, furnishing unfunctionalized chiral imines efficiently(up to 99% yield, >99% ee).The(Z)-allylamines and(E)-allylamines were also efficiently prepared from alkynone imines by the combination of the different catalytic systems. The preliminary mechanism study revealed that the reduction of alkynone imines was a stepwise process and the C=N bonds were preferably hydrogenated in the complete reduction of alkynone imines. The synthetic utility of this method was demonstrated by its application in the late-stage modification of the antiviral drug Zidovudine and the concise synthesis of chiral dibenzoazepine.

Synthesis of Cyclic Carbonates from Alkenyl and Alkynyl Substrates

As an extensively used chemical product,cyclic carbonate was generally synthesized by transesterification,or the cycloaddition of epoxides,diols with CO2.To reduce the production costs and expand the raw materials,alkenyl and alkynyl substrates have caused much attention in the synthesis of cyclic carbonates,such as olefins,allyl alcohols and propargylic alcohols.Based on the alkenyl substrate,the synthetic process involves a continuous reaction of oxidative carboxylation,with epoxide or halohydrin as an intermediate usually.Therefore,peroxides and nucleophiles （halogens or organic bases） are often necessary in the conversion.Using propargylic alcohols to produce a-alkylidene cyclic carbonates,noble metal catalysts play crucial roles in alkynyl activation,and organic bases are considered to assist the intramolecular and intermolecular proton transfer and combine CO2 molecular.As the carboxyl sources in products,inorganic carbonates and organic carboxylic acids also have some applications instead of CO2.In this review,we summarized the synthetic routes of cyclic carbonates from alkenyl and alkynyl substrates in the aspect of catalyst,mechanism and the development tendency.