1,3-Diyne chemistry: synthesis and derivations

Conjugated diynes have attracted more and more attention not only for their unique rod like structures and wide existence in nature product, but also the abundant properties and derivations of them. Although oxidative dimerization of alkynes or Cadiot–Chodkiewicz reactions were the main pathway and have achieved great success in the synthesis of diynes, oxidative cross coupling, FBW rearrangement as well as diyne metathesis emerged rapidly recently. Moreover, diynes could be precursors of basic heterocycles, which represented an emerging research area. This Letter will cover the recent progresses in the synthesis and further derivations of diynes.     

Preparation of diynes via selective bisalkynylation of zirconacycles

Reaction of alkynyl halides with in situ prepared zirconacyclopentanes, -pentenes, and -pentadienes in the presence of CuCl under mild reaction conditions afforded alkynes or diynes. Control of the reaction conditions selectively afforded monoalkynylation products of zirconacycles. Reaction of zirconacycles with 2 equiv of alkynyl halides resulted in the formation of diynes. Selective monoalkynylation of zirconacycle with an alkynyl halide, followed by reaction with a different alkynyl halide, afforded unsymmetrical diynes. Bisalkynylation product of zirconacyclopentadiene was gradually converted into a tricyclic compound.     

Polyunsaturated alkyl amides from Echinacea: synthesis of diynes, enynes, and dienes

The synthesis of 20 alkyl amides, including 15 naturally occurring polyunsaturated alkyl amides previously identified from Echinacea spp. (1-13 and 62) or from Achilla sp. (55) and five previously unknown geometric isomers (23, 28, 67, 73, and 80), is described. Importantly, these amides include all of the major alkyl amides present in commercially used Echinacea extracts. The syntheses demonstrate methodology used for constructing alkyl amides containing conjugated diyne and isomerically pure enyne and diene moieties and may be adapted easily for the preparation of other alkyl amides present in Echinacea spp. Terminal-conjugated diynes were prepared by a Cadiot-Chodkiewitz coupling/deprotection sequence utilizing a protected bromoacetylene, and methyl-substituted diynes were made via a base-catalyzed rearrangement of terminal-skipped diynes. Conjugated dienes were prepared conveniently and with high stereoselectivity by the reduction of enynes or diynes with Rieke zinc. With the exception of 1-2 and 11-12, the alkyl amides are synthesized here for the first time, and their NMR data are consistent with that of the reported isolated natural compounds.     

Zirconocene-mediated, high-yielding macrocyclizations of silyl-terminated diynes

A series of silyl-terminated diynes of varying lengths and substitution patterns have been prepared. These diynes undergo zirconocene coupling with selective formation of trimeric macrocycles from linear alkynes, while nonlinear diynes give cyclodimeric products. The length of the linear diynes can be increased for the preparation of macrocycles with large nanoscale cavities. Reaction of the zirconium-containing macrocycles with acid results in the synthesis of metal-free cyclophanes. All of these macrocycles were prepared in multigram quantities, in the absence of high-dilution conditions, to give products in > 75% yield that are easily purified as crystalline solids.     

Ni-catalyzed highly regio- and chemoselective cocycloaddition of nonconjugated diynes with 1,3-diynes: a novel method for polysubstituted arylalkynes

[reaction: see text] Effective nickel-catalyzed cocycloaddition of nonconjugated diynes with conjugated diynes yields polysubstituted arylalkynes in good to excellent yields with high regio- and chemoselectivity.     

Synthesis of Spirocyclic C‐Arylglycosides and ‐Ribosides by Ruthenium‐Catalyzed Cycloaddition

Spirocyclic C‐arylglycosides were synthesized from the appropriately protected δ‐gluconolactones. Addition of lithium acetylide followed by glycosylation with 3‐(trimethylsilyl)propargyl alcohol converted the δ‐gluconolactones into silylated diynes. After desilylation, subsequent ruthenium‐catalyzed cycloaddition of the resultant diynes with alkynes or chloroacetonitrile gave spirocyclic C‐arylglycosides in good yields and selectivity. This strategy was also extended to the synthesis of spirocyclic C‐arylribosides from the known γ‐ribonolactone derivative. Moreover, silver‐catalyzed iodination of the sugar diynes followed by ruthenium‐catalyzed cycloaddition with acetylene delivered spirocyclic C‐iodophenylglycosides and ‐ribosides, which were subjected to palladium‐catalyzed C? C bond‐forming reactions and copper‐catalyzed coupling with nitrogen heterocycles to lead to various derivatives.     

Hydroboration,haloboration and phenylboration polymerizations

A polyaddition between diene and monoalkylborane produced a polymer consisting of C-B bonds in the main chain. The resulting organoboron polymers can be used as a novel type of reactive polymers. On the other hand, hydroboration polymerization of dicyano compounds produced air-stable poly(cyclodiborazane)s having B-N four-membered rings via dimerization of iminoborane species. Poly(organoboron halide)s were prepared either by haloboration polymerization between diynes and boron tribromide or by hydroboration polymerization of dienes with monobromoborane. Furthermore, phenylboration polymerization of diynes or diisocyanates gave new organoboron mainchain polymers.     

端基炔烃的简单快速二聚反应

端基炔烃在无钯催化剂的条件下, 以乙腈为溶剂, 三乙胺为碱, 与氯化亚铜和二醋酸碘苯反应, 常温下短时间内得到高产率的二聚产物, 提供了一个简单快速合成共轭二炔烃的新方法. 比较了反应条件, 并提出了可能的反应机理.     

Retracted: A Facile Synthetic Route to New Fluorinated Building‐Blocks of 1‐Fluoroalkynes and 1‐Fluorodiynes

A facile and direct fluorination process of alkynes and diynes was developed. In the presence of n‐butyllithium, the reaction of a series of terminal alkynes and diynes with the electrophilic fluorinating reagent (NFSI) proceeded to afford various 1‐fluoroalkynes and 1‐fluoro‐1,3‐diynes in moderate to high yields.     

Copper‐Catalyzed Aerobic Oxidative Transformation of Ketone‐Derived N‐Tosyl Hydrazones: An Entry to Alkynes

A novel strategy involving Cu‐catalyzed oxidative transformation of ketone‐derived hydrazone moiety to various synthetic valuable internal alkynes and diynes has been developed. This method features inexpensive metal catalyst, green oxidant, good functional group tolerance, high regioselectivity and readily available starting materials. Oxidative deprotonation reactions were carried out to form internal alkynes and symmetrical diynes. Cross‐coupling reactions of hydrazones with halides and terminal alkynes were performed to afford functionalized alkynes and unsymmetrical conjugated diynes. A mechanism proceeding through a Cu‐carbene intermediate is proposed for the C? C triple bond formation.     

An in situ approach for nickel-catalyzed cycloaddition

A convenient method for preparing pyridines from air-stable, commercially available catalyst precursors is described. The addition of n-BuLi to Ni(acac)2 and an NHC salt (such as IPr.HCl or SIPr.HCl) rapidly generates an active Ni0/NHC catalyst for the cycloaddition of diynes and nitriles that affords pyridines without a decrease in observed yields. The in situ method also converts diynes and carbon dioxide to the corresponding pyrones.     

Nickel-catalyzed cycloaddition of alkynes and isocyanates

A mild and general route for preparing 2-pyridones from isocyanates and diynes is described. Ni imidazolyidene complexes were used to mediate cyclizations between both internal and terminal diynes with aryl and alkyl isocyanates. In addition, the efficacy of this protocol allows for the preparation of a fused seven-membered pyridone and for three component cyclizations.     

Investigations on the synthesis of monoarylated diynes by monoprotection/cross-coupling/deprotection approach

The presented experimental work investigates the usefulness of temporary monoprotection of symmetrical terminal diynes in the coupling with aryl iodides. The monoprotection/cross-coupling/deprotection approach proved to be efficient for the coupling of diynes with aryl substrates avoiding the formation of diarylated byproducts. The high importance of the ratio of solvents in the Sonogashira coupling is demonstrated.     

An efficient synthesis of diynes using (diacetoxyiodo)benzene

A novel and facile method for synthesis of symmetrical conjugated diynes, using (diacetoxyiodo)benzene as oxidant under palladium-catalyzed conditions is presented, in which diynes are prepared in good yields in a short period of time at room temperature.     

Synthesis of Unsymmetrical 1,3‐Diynes via Pd/Cu‐Catalyzed Cross‐Coupling of Terminal Alkynes at Room Temperature

A facile and practical synthetic route of unsymmetrical 1,3‐diynes via the PdCl/CuI catalyzed oxidative coupling of two different terminal alkynes has been developed by using 3‐(diphenylphosphino)propanoic acid as a ligand in the presence of oxygen. This system is suitable for not only aromatic alkynes but also heteroaromatic and aliphatic alkynes which were transformed into the corresponding unsymmetrical 1,3‐diynes in moderate to good yields at room temperature. Moreover, the unsymmetrical 1,3‐diynes were also obtained on a multi‐gram scale. Mechanistic studies suggest that oxygen plays a key role in the catalytic cycles.     

Catalytic and Enantioselective Synthesis of Chiral Multisubstituted Tribenzothiepins by Intermolecular Cycloadditions

The first catalytic and highly enantioselective synthesis of tribenzothiepin derivatives was achieved. Two types of intermolecular cycloadditions using either diphenyl‐sulfide‐tethered diynes or 2‐phenyl sulfanylbenzene‐tethered diynes with a monoalkyne successfully gave chiral multisubstituted tribenzothiepins in good to excellent ee values under mild conditions. The inversion energy of this saddle‐shaped molecule was calculated by measurement of the racemization rate of chiral tribenzothiepins using the Eyring kinetic equation under heating conditions. The present protocol could also be used to prepare a chiral tribenzoselenepin.     

Organic Polyvalent Iodinc Reagents-Promoted Coupling Reaction of 1-Alkynes

Sincetheearlyl980sinterestin0rganicpoIyvalentiodinec0mp0undshasexperiencedaresurgence'.Afewexamplesofhomo-couplingreacti0nsviathesec0mpoundshavebeenrep0rted-.Wef0undthatl-aIkyneswereeasytoc0upleinthepresenceofPhI(OAc)=orPhI(OH)OTs,catalyticCulandbase,t0aff0rdc0njugateddiynes.l,3-Diyneplaysanimportantr0leinstudiesofm0lecularrec0ngnition',innaturalpr0ducts',andinsynthesis.AlthoughEglintonreaction',Cadi0t-Chalkiewiczc0upling'andGlaserreaction5haveprovidedc0nvenientmeth0dst0synthesizeconjug…     

The interaction of poly(methacrylate) radicals with diphenyldiacetylenes

The free radical polymerization of methyl methacrylate (MMA) in the presence of p,p′- disubstituted diphenylbutadiynes was studied. Both the rate and degree of polymerization are somewhat lowered by the presence of the diynes, but the propagating radicals were stabilized giving clear ESR signals of the interacted polyMMA radicals at the polymerization temperature of 70°C. The magnitude of the interaction depended on the electron density of the diynes; in the cases of diphenylbutadiyne and dimethoxycarbonyldiphenylbutadiyne, the intoraction was more enhanced showing ESR signals with smaller spectra widths and increasing the number of radicals with the polymerization time, while in the cases of electron donor-substituted diynes the interaction was weaker and the radical concentration remained constant during the polymerization. These systems are considered to be examples of the stabilization of transient radicals by the direct interaction of radicals with additives without formation or breaking of chemical bonds. No diacetylenic group was found in the polyMMA obtained. © 1994 John Wiley & Sons, Inc.     

A strictly "pair"-selective synthesis of conjugated diynes via Pd-catalyzed cross coupling of 1,3-diynylzincs: a superior alternative to the Cadiot-Chodkiewicz reaction

A strictly "pair"-selective synthesis of conjugated diynes via Pd-catalyzed cross coupling of 1,3-diynylzincs is described. This method, like the Cadiot-Chodkiewicz reaction, requires three steps for the synthesis of R(1)Ctbd1;CCtbd1;CR(2) from R(1)Ctbd1;CH, R(2)X, and HCtbd1;CH. However, the high "pair"-selectivity permitting high-yield production of the desired conjugated diynes without separation of symmetrical diynes promises to make the present protocol superior to the Cadiot-Chodkiewicz reaction in many cases.     

Ruthenium-catalyzed transfer oxygenative cyclization of α,ω-diynes: unprecedented [2 + 2 + 1] route to bicyclic furans via ruthenacyclopentatriene

A novel oxygen-atom-transfer process enables the catalytic [2 + 2 + 1] synthesis of bicyclic furans from α,ω-diynes with DMSO. [CpRu(AN)(3)]PF(6) catalyzed the transfer oxygenative cyclization of diynes with aryl terminal groups, while those of diynes with alkyl terminal groups were effectively promoted by the corresponding Cp* complex. A mechanism for bicyclic furan formation via a ruthenacyclopentatriene was proposed on the basis of both experimental and theoretical studies.