锆诱导的五元环化合物的新和成

由锆杂五元环化合物出发合成五元环有机化合物,只要求一个碳单元并且形成两个碳-碳链,从以下四个方面描述了利用锆杂环化物合成五元环有机化合物的新合成方法：(1)CO或RNC的插入反应;(2)与丙炔酸酯的加成反应-峡谷次的Michael加成;(3)与碘代丙烯酸酯或碘代环烯酮的偶联加成反应-先偶联后Michael加成;(4)与酰氯的取代加成反应-先亲核取代后亲核加成,每类反应都含有数个简单反应类型。     

Preparation of 5-hydroxy-1-alkenyboronates from 1-alkynylboronates, Cp2ZrCl2/2EtMgBr, and aldehydes

1-Alkynylboronates form five-membered zirconacycles with Cp(2)ZrCl(2)/2-EtMgBr as indicated by deuterium labeling. The zirconacycles add aldehydes to form seven-membered zirconacycles. Hydrolysis of the latter provides 5-hydroxy-1-alkenylboronates in fair to good isolated yields. Both aliphatic and aromatic aldehydes undergo insertion.     

Ring expansion of 5- to 6-member zirconacycles by carbenoid insertion

A wide range of carbenoids (1-lithio-1-halo species), including those with α-SiR₃, OEt, SPh, SO₂Ph, P(O)(OEt)₂, and CN substituents, insert into 5-member zirconacycles (saturated and unsaturated, mono- and bi-cyclic) to afford functionalized 6-member zirconacycles. 1-Lithio-1-haloalkenes insert to afford 6-member zirconacycles with an alkylidene substituent next to the metal. Unexpected double insertion of some carbenoids, and evidence for endocylic β-hydride transfer processes provide additional mechanistic interest.     

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.     

Organometallic chemistry at the edge of polycyclic aromatic hydrocarbons

Zirconocene and bisphosphine nickel chemistry developed in our labs and directed towards the derivatization and synthesis of polycyclic aromatic carbon compounds is reviewed. Complexes with the formula Cp₂ZrMe(η¹-PAC) (PAC=anionic polycyclic aromatic carbon ligand) eliminate methane to produce zirconacycles and yne complexes. Treatment of the zirconacycles with L₂NiX₂ (L=phosphine, X=Cl, Br) in the presence of alkynes results in metallacycle transfer to nickel and cycloaddition of the alkyne. The resulting polycyclic aromatic carbon compounds contain an additional ring. The nickelacycles may also be accessed by oxidative addition of Ni(0) to polycyclic aromatic dihalides followed by reduction. The application of this chemistry to the step-growth synthesis of single-walled carbon nanotubes is proposed.     

Reaction of zirconocene dichloride with alkyllithiums or alkyl grignard reagents as a convenient method for generating a “zirconocene” equivalant and its use in zirconium-promoted cyclization of alkenes,alkynes, dienes,enynes, and diynes

Treatment of Cl₂ZrCp₂ with 2 equiv of alkylmetals (RM) containing Li or Mg, e.g., n-BuLi, in THF produces organozirconium species that act as sources of “ZrCp₂,” the latter product being a convenient reagent for preparing zirconacycles.     

Intermolecular hydroamination of oxygen-substituted allenes. New routes for the synthesis of N,O-chelated zirconium and titanium amido complexes

Intermolecular hydroamination of heteroatom-substituted allenes with a bulky arylamine was carried out using a bis(amidate) bis(amido) titanium(IV) complex (1) as a precatalyst. The reaction of 2,6-dimethylaniline with oxygen-substituted allene 2c or 2d in the presence of complex 1 gives the ketimine regioisomer as the exclusive product. Reduction of such ketimine products resulted in the formation of amino ethers that were further employed as proligands for the formation of N,O-chelating five-membered titana- and zirconacycles. Such sterically demanding N,O-chelating ligands result in the high-yielding preparation of mono-ligated products. Solid-state molecular structures of all the complexes revealed distorted trigonal bipyramidal geometry about the metal centers, with a dative bond between the metal and the oxygen donor atom. These new complexes obtained using hydroamination as the key-step in ligand preparation were also shown to be useful cyclohydroamination precatalysts in their own right.     

Synthesis of carborane-fused cyclobutenes and cyclobutanes

Transmetalation of carborane-fused zirconacycles to Cu(Ⅱ) induces the C-C coupling reaction to form four-membered rings. This serves as a new efficient and general methodology for the generation of a series of carborane-fused cyclobutenes and cyclobutanes. A reaction mechanism involving transmetalation to Cu(Ⅱ) and reductive elimination is proposed.     

Five-membered metallacycles of titanium and zirconium--attractive compounds for organometallic chemistry and catalysis

In these days a renaissance of metallacycles as an increasingly important class of organometallic compounds for synthetic and catalytic applications is evident, making such very attractive for a plethora of investigations. Titanocene and zirconocene bis(trimethylsilyl)acetylene complexes, regarded as three-membered metallacycles (1-metallacyclopropenes), present a rich chemistry towards unsaturated molecules. By elimination of the alkyne these complexes form by reaction with unsaturated compounds five-membered titana- and zirconacycles, all of which are relevant to stoichiometric and catalytic C-C coupling and cleavage reactions of unsaturated molecules.     

Reaction of zirconacycles with 3-iodopropenoates and 3-iodocycloenones in the presence of CuCl: A new pathway for the formation of cyclopentadienes and spirocyclic compounds

Formation of cyclic compounds from zirconacycles has been performed by a combination of Michael addition and coupling with an alkenyl iodide moiety in the presence of a stoichiometric amount of CuCl. The reaction of 3-iodopropenoates with various zirconacyclopentadienes in the presence of a stoichiometric amount of CuCl afforded penta- and hexasubstituted cyclopentadienes. The reaction of 3-iodocycloenones with zirconacyclopentadienes, zirconacyclopentenes, or zirconacyclopentanes gave spirocyclic compounds in good yields.     

Insertion Reaction of Aldehydes into Zirconacyclopentanes

Aldehydes reacted with zirconacyclopentane derivatives via insertion into the Zr‐sp³C bond to afford the corresponding 7‐membered zirconacycles.     

Alternative reaction pathways in domino reactions of hydrazinediidozirconium complexes with alkynes

Reaction of [Zr{(NAr)(2)N(py)}(NMe(2))(2)] (Ar=3,5-xylyl: 2?a, mesityl: 2?b) with one or two molar equivalents of 1,1-diphenylhydrazine gave the mixed amido/hydrazido(1-) complex [Zr{(NMes)(2)N(py)}(HNNPh(2))(NMe(2))] (3), the bis-hydrazido complex [Zr{(NMes)(2)N(py)}(HNNPh(2))(2)] (4), and, in the presence of excess 4-dimethylaminopyridine (DMAP), hexacoordinate hydrazinediidozirconium complexes [Zr{(NXyl)(2)N(py)}(=NN(Me)Ph)(dmap)(2)] (5) and [Zr{(NXyl)(2)N(py)}(=NNPh(2))(dmap)(2)] (6). The reaction of one equivalent of the zirconium-hydrazinediide [Zr{(NTBS)(2)N(py)}(NNPh(2))(py)] (1) with disubstituted alkynes at RT for 16?h led to the formation of seven-membered diazazirconacycles 7?a-7?e in high yields. Similar reactivity was observed by reacting bis-amido complex 2?b with one molar equivalent of the corresponding alkyne and diphenylhydrazine. The formation of the seven-membered zirconacycles implied a key coupling step that involved the alkyne and one of the aryl rings of the diphenylhydrazinediido ligand. In some cases, such as the reaction with 2-butyne, the corresponding metallacycle was only obtained in modest yields (45?% for the reaction with 2-butyne) and a second major product, vinylimido complex 9, was formed in almost equal amounts (42?%) by 1,2-amination (formal insertion of the alkyne). The formation of compounds 7?a and 9 followed in part the same sequence of reaction steps and a key intermediate, an azirinido complex, represented a "bifurcation point" in the reaction network. Reaction of 1.2?equivalents of several diarylhydrazines and various substituted alkynes (1?equiv) at ambient temperature (or at 80?°C) in the presence of 10?mol?% [Zr{(NXyl)(2)N(py)}(NMe(2))(2)] (2?a) gave the corresponding indole derivatives. On the other hand, the replacement of 1,1-diarylhydrazines by 1-methyl-1-phenyl hydrazine led to head-to-head cis-1,3-enynes in good yields.     

A controllable synthesis of homoallyl ketones and multiply substituted cyclopentadienes by direct insertion of aroyl cyanides to zirconacyclopentenes

[reaction: see text] The direct reaction of aroyl cyanides with zirconacyclopentenes was achieved cleanly under controlled reaction conditions. This methodology provided an extremely efficient, one-pot, and high-yield route for the synthesis of homoallyl ketones when the reaction was carried out at -50 degrees C. Trapping of the zirconium intermediate by a variety of electrophiles afforded functionalized homoallyl ketones. Remarkably, the insertion reaction occurred with complete chemoselectivity, that means, the Zr-sp3 carbon bond reacted preferentially, which is different from Cu-mediated elaboration of zirconacycles. Surprisingly, when the reaction was done at room temperature, 1,2,3-trisubstituted cyclopentadiene derivatives were readily formed in high yields. The direct insertion reaction of zirconacyclopentanes with acyl cyanides was also described. When bicyclic zirconacyclopentanes were used, cyclopentanol derivatives were obtained with high stereoselectivity.     

2,3-Diarylbenzo[b]arsole: Structural Modification and Polymerization for Tuning of Photophysical Properties

2,3-Diarylbenzo[b]arsoles were synthesized from zirconacycles and diiodophenylarsine. The structural modification to the luminophore was attained through diarylacetylene precursors, Suzuki–Miyaura coupling, and oxidation of the arsenic atom. The emission properties were controlled according to these modifications. The 2,3-diarylbenzo[b]arsoles showed aggregation-induced emission enhancement; the stronger emission was observed in the solid states than in solutions. In addition, Suzuki–Miyaura polycondensation and olefin metathesis polymerization produced main- and side-chain polymers, respectively. The resultant polymers showed different emission behaviors such as aggregation caused quenching and aggregation induced emission enhancement.     

Carbon-carbon bond formation of alkenylphosphonates by aldehyde insertion into zirconacycle phosphonates

Ethyl 1-butynylphosphonate reacts with Cp(2)ZrCl(2)/2n-BuLi to give a three-membered zirconacycle that readily inserts aldehydes. Hydrolysis of the intermediate five-membered zirconacycles leads to two products, 4 and 5. In the major product, 5, the aldehyde inserts into C2 of the zirconacycle, while in the minor product, 4, the aldehyde inserts into C1. Products 5 are obtained in 38-75% isolated yields. Products 4 are obtained in approximately 1-12%. Essentially, only compounds 5 are produced with ortho-substituted aldehydes. The regio- and stereochemistry of 4 and 5 were determined by (3)J(PH), (2)J(PC2), and (3)J(PC3) coupling constants.     

A facile synthesis of 2-oxo-cyclopentenylphosphonates by carbonylation of zirconacyclopentenylphosphonate with oxalyl chloride

Addition of oxalyl chloride to zirconacycles prepared from 1-alkynylphosphonates 1 zirconocene dichloride, and two equivalents of EtMgBr smoothly produced novel 2-oxo-cyclopentenylphosphonates 6 in 58–81% isolated yields in the presence of a copper catalyst.     

Formation,preservation, and cleavage of the disulfide bond by vanadium

Reaction of the disulfide [HpicanS](2) (HpicanS is the carboxamide based on picolinate (pic) and o-mercaptoaniline (anS); the [] brackets are used to denote disulfides) with [VOCl(2)(thf)(2)] leads to reductive scission of the disulfide bond and formation of the mixed-valence (V(IV)/V(V)) complex anion [(OVpicanS)(2)mu-O](-) (1), with the dianionic ligand coordinating through the pyridine-N atom, the deprotonated amide-N atom, and thiophenolate-S atom. Reductive cleavage of the SbondS bond is also observed as [VCl(2)(tmeda)(2)] (tmeda=tetramethylethylenediamine) is treated with the disulfides [HsalanS](2) or [HvananS](2) (HsalanS and HvananS are the Schiff bases formed between o-mercaptoaniline and salicylaldehyde (Hsal) or vanillin (Hvan), respectively), yielding the V(III) complexes [VCl(tmeda)(salanS)] (2 a), or [VCl(tmeda)(vananS)] (2 b). The disulfide bond remains intact in the aerial reaction between [HsalanS](2) and [VCl(3)(thf)(3)] to yield the V(V) complex [VOCl[salanS](2)] (3), where (salanS)(2-) coordinates through the two phenolate and one of the imine functions. The S-S bond is also preserved as [VO(van)(2)] or [VO(nap)(2)] (Hnap=2-hydroxynaphthalene-1-carbaldehyde) is treated with bis(2-aminophenyl)disulfide, [anS](2), a reaction which is accompanied by condensation of the aldehyde and the diamine, and complexation of the resulting bis(Schiff bases) [HvananS](2) or [HnapanS](2) to form the complexes [VO[vananS](2)] (4 a) or [VO[napanS](2)] (4 b). In 4 a and 4 b, the phenolate and imine functions, and presumably also one of the disulfide-S atoms, coordinate to V(IV). 2-Mercaptophenyl-2'-pyridinecarboxamide (H(2)picanS) retains its identity in the presence of V(III); reaction between [VCl(3)(thf)(3)] and H(2)picanS yields [V[picanS](2)](-) (5). The dithiophenolate 2,6-bis(mercaptophenylthio)dimethylpyridine (6 a) is oxidized, mediated by VO(2+), to the bis(disulfide) octathiadiaza-cyclo-hexaeicosane 6 b. The relevance of these reactions for the speciation of vanadium under physiological conditions is addressed. [HNEt(3)]-1.0.5 NEt(3,) 3.3 CH(2)Cl(2), [HsalanS](2), [HNEt(3)]-5, and 6 b.4 THF have been characterized by X-ray diffraction analysis.     

Zirconocene Mediated Diastereo- and Enantioselective Synthesis of 4,5,5-Trisubstituted 2-Alkoxytetrahydrofurans

1-Aza-2-zirconacyclopent-4-enes 3, prepared from α,β-unsaturated imines 2 were used as homoenolate-equivalents to generate 3-aza-1-oxa-2-zirconacyclohept-4-enes 4 via the diastereoselective insertion of prochiral, sterically demanding ketones. Hydrolysis of the zirconacycles using our pyridinium-N-oxide method led to the formation of 4,4,5-substituted 4-phenyltetrahydro-2-furanyl-Narylamines 5 in high diastereomeric purity. A simple method for their conversion into α-methoxytetrahydrofurans 6a-g by treatment with methanol/THF and catalytic amounts of TsOH was developed. The α-methoxytetrahydrofurans 6a-g were easily transformed into 2,2,3-substituted 2,3-dihydrofurans 7 in good overall yields using an acidic elimination step. Benzyl protected γ-butyrolactols 6h-j could be generated in a one-pot procedure. Additionally, first efforts to perform this synthesis enantioselectively are described.     

Metal telluride clusters composed of niobocene carbonyl, telluride, and cobalt carbonyl units: syntheses, structures, and reactivity

Abstract: The reaction of [Cp#2NbTe2H] (1#; Cp# = Cp* (C5Me5) or Cp(x) (C5Me4Et)) with two equivalents of [Co2(CO)8] gives a series of cobalt carbonyl telluride clusters that contain different types of niobocene carbonyl fragments. At 0 degrees C, [Cp#2NbTe2CO3(CO)7] (2#) and [Co4Te2(CO)10] (3) are formed which disappear at higher temperatures: in boiling toluene a mixture of [cat2][Co9Te6(CO)8] (5#) (cat= [Cp#2Nb(CO)2]+) and [cat2][Co11Te7(CO)10] (6#) is formed along with [cat][Co(CO)4] (4#). Complexes 6# transform into [cat][Co11Te7(CO)10] (7#) upon interaction with HPF6 or wet SiO2. The molecular structures of 2(Cp(x)), 4(Cp(x)), 5(Cp*), 6(Cp*) and 7(Cp*) have been determined by X-ray crystallography. The structure of the neutral 2(Cp(x)) consists of a [Co3(CO)6Te2] bipyramid which is connected to a [(C5Me4Et)2Nb(CO)] fragment through a mu4-Te bridge. The ionic structures of 4(Cp(x)), 5(Cp*), 6(Cp*) and 7(Cp*) each contain one (4, 7) or two (5, 6) [Cp#2Nb(CO)2]+ cations. Apart from 4, the anionic counterparts each contain an interstitial Co atom and are hexacapped cubic cluster anions [Co9Te6(CO)8]2- (5) or heptacapped pentagonal prismatic cluster anions [Co11Te7(CO)10]n- (n=2: [6]2- , n=1: [7]-), respectively. Electrochemical studies established a reversible electron transfer between the anionic clusters [Co11,Te7(CO)10]- and [Co11Te7(CO)10]2in 6# and 7# and provided evidence for the existence of species containing [Co11Te7(CO),0] and [Co11Te7(CO)0]3-. The electronic structures of the new clusters and their relative stabilities are examined by means of DFT calculations.     

Iodide, azide, and cyanide complexes of (N,C), (N,N), and (N,O) metallacycles of tetra- and pentavalent uranium

In contrast to the neutral macrocycle [UN*(2)(N,C)] (1) [N* = N(SiMe(3))(3); N,C = CH(2)SiMe(2)N(SiMe(3))] which was quite inert toward I(2), the anionic bismetallacycle [NaUN*(N,C)(2)] (2) was readily transformed into the enlarged monometallacycle [UN*(N,N)I] (4) [N,N = (Me(3)Si)NSiMe(2)CH(2)CH(2)SiMe(2)N(SiMe(3))] resulting from C-C coupling of the two CH(2) groups, and [NaUN*(N,O)(2)] (3) [N,O = OC(═CH(2))SiMe(2)N(SiMe(3))], which is devoid of any U-C bond, was oxidized into the U(V) bismetallacycle [Na{UN*(N,O)(2)}(2)(μ-I)] (5). Sodium amalgam reduction of 4 gave the U(III) compound [UN*(N,N)] (6). Addition of MN(3) or MCN to the (N,C), (N,N), and (N,O) metallacycles 1, 4, and 5 led to the formation of the anionic azide or cyanide derivatives M[UN*(2)(N,C)(N(3))] [M = Na, 7a or Na(15-crown-5), 7b], M[UN*(2)(N,C)(CN)] [M = NEt(4), 8a or Na(15-crown-5), 8b or K(18-crown-6), 8c], M[UN*(N,N)(N(3))(2)] [M = Na, 9a or Na(THF)(4), 9b], [NEt(4)][UN*(N,N)(CN)(2)] (10), M[UN*(N,O)(2)(N(3))] [M = Na, 11a or Na(15-crown-5), 11b], M[UN*(N,O)(2)(CN)] [M = NEt(4), 12a or Na(15-crown-5), 12b]. In the presence of excess iodine in THF, the cyanide 12a was converted back into the iodide 5, while the azide 11a was transformed into the neutral U(V) complex [U(N{SiMe(3)}SiMe(2)C{CHI}O)(2)I(THF)] (13). The X-ray crystal structures of 4, 7b, 8a-c, 9b, 10, 12b, and 13 were determined.