Search

We report a new cyclization reaction of amides with ynones via tandem amide α-C–H and C–N activation enabled by a non-redox rare earth catalyst.

Rare-earth-mediated selective endocyclic and exocyclic Si–C(sp3) bond cleavage of a silyl-modified silylamido ligand was realized through the nucleophilic addition of unsaturated molecules such as CO, CS2, and organonitriles.

Unprecedentedly preferential reduction of unstrained C(sp3)–C(sp3) bond over ketone, hydrogenative [2+2+2]-cycloreversion of 2,4-diacylcyclohexanols, and cyclizative degradation of poly(vinylketone) have been achieved by organolanthanide catalysis.

Herein we report the first catalytic decarbonylation and decarbonylative hydroamination of formamides without using additives enabled by a redox-neutral rare earth catalyst. The protocol displays complete

A rare earth metal-catalyzed sequential inter- and intramolecular C-N bond formation of 2-nitrile-2'-alkenyl(alkynyl)biphenyls with amines has been developed, which provides a straightforward and efficient access to a range of new functional dibenzo[c,e]azepines. This represents the first examples of direct construction of seven-membered azaheterocycle from unsaturated nitriles and amines. Such transformations have the advantages of avoiding the use of additives, easily available starting materials, step- and high atom-economy, mild reaction conditions, and high selectivity.

The C–C bond reduction and metathesis are fundamentally important in organic synthesis. However, homogeneously reducible C–C bonds are currently limited to either strained rings or to specific and prefunctionalized sites; and there are no practical methods for tandem C–C reduction and intramolecular C(sp3)–C(sp3) metathesis. Here we report a versatile approach for selective reduction of unstrained C(sp3)–C(sp3) bond of ketones, including hydrogenolytic retro-[2+2+2]-cycloreversion of 2,4-diaroylcyclohexanols, without requiring protecting groups. We have also established an unprecedented intramolecular C(sp3)–C(sp3) metathesis, thus enabling the cyclizative degradation of poly(vinylketone). The present C–C cleavage occurs via a bimetallic pathway and nucleophile trapping of resulting enone is crucial for C–C cleavage relay. These results would open new prospect for deconstruction of organic molecules.

A rare earth metal-catalyzed sequential inter- and intramolecular C-N bond formation of 2-nitrile-2'-alkenyl(alkynyl)biphenyls with amines has been developed, which provides a straightforward and efficient access to a range of new functional dibenzo[

The rare-earth-metal organic cyclo-P4 complex (LY·DMAP)2[1,2-R2- cyclo-P4] (2, L = N, N'-2,6-diisopropylphenyl-1,4-diazabutadiene, DMAP = 4- N, N'-dimethylpyridine, R = CH2C6H4NMe2-2) was synthesized by direct functionalization of P4 using the rare-earth-metal alkyl complex LYR(THF) (1) for the first time. Further investigations indicated that three selective conversions of the cyclo-P4 species have been realized by alkyl migration. Complex 2 was slowly transformed into a R2P-substituted cyclo-P3 cluster (LY·DMAP)2[ cyclo-P3PR2] (3) under heating conditions. The reaction of 2 with 1 equiv of KR gave the unsubstituted cyclo-P3 complex (LY·THF)2[ cyclo-P3]K (4) in quantitative yield, accompanied by the elimination of the organophosphorus compound PR3 (5). Treatment of 2 with HMPA afforded the structurally characterized Zintl-type P7 complex (LY·HMPA)3P7 (6). The formation of complexes 3, 4, and 6 revealed that unusual alkyl migrations in the polyphosphorus complexes occurred in these reactions, and the transformations from cyclo-P4 into cyclo-P3 also provided a new insight into the stepwise degradation of P4 using metal complexes.

An efficient method for preparation of substituted 1,2-phenylenedimethanols and aliphatic 1,4-diols that are valuable intermediates in organic synthesis, has been developed by the base-promoted reduction of isobenzofuran-1(3H)-ones and γ-lactones with silane under mild conditions. Compared with traditional procedures using stoichiometric amounts of metal hydrides and alkyl reductants, the present method avoids the use of sensitive reagents and is operationally simple and a broad variety of functional groups are tolerated.

Mononuclear amidinate yttrium complex C4 H9 C(NR)2 Y(o-CH2 C6 H4 NMe2 )2 (R=2,6-iPr2 C6 H3 ) and a series of binuclear rare-earth metal complexes bearing a bridged amidinate ligand [(RN)2 C(CH2 )4 C(NR)2 ][RE{CH2 C6 H4 (o-NMe2 )}2 ]2 (R=2,6-iPr2 C6 H3 , RE=Y, Lu, Sc) were synthesized and fully characterized. The catalytic behavior of these complexes for (co)polymerization of conjugated dienes such as isoprene and myrcene in the presence of co-catalyst [Ph3 C][B(C6 F5 )4 ] was investigated. These catalytic systems show impressively high activity and 3,4-regioselectivity in living (co)polymerization. The binuclear bridged amidinate yttrium catalytic system not only exhibits the highest activity among the reported catalytic systems for 3,4-polymerization of isoprene but also allows the steady polymerization in a living manner from -20 to 80 °C. Compared with the dramatic drop of 3,4-selectivity for the mononuclear analogue, the binuclear catalytic system still shows moderate 3,4-selectivity at 80 °C. Moreover, a facile one-pot synthetic strategy for a polymer blend containing 3,4- and 1,4-polyisoprene (PIP) was established through the in situ modification of the active amidinate yttrium species by addition of an excess amount of AlMe3 .

A new method for the modification of a silylamino ligand has been developed through mono and dual C(sp3 )-H/Si-H cross-dehydrocoupling with silanes. The reaction of [LY{η2 -(C,N)-CH2 Si(Me2 )NSiMe3 }] (L=bis(2,6-diisopropylphenyl)-β-diketiminato, L' (1L '); L=tris(3,5-dimethylpyrazolyl)borate, TpMe2 (1TpMe2 )) with 2 equivalents of PhSiH3 in toluene gave the complexes [LY{η2 -(C,N)-C(SiH2 Ph)2 Si(Me2 )NSiMe3 }] (L=L' (2L' ); L=TpMe2 (2TpMe2 )). Moreover, 1TpMe2 reacted with the secondary silanes Ph2 SiH2 and Et2 SiH2 to afford the corresponding mono C-H activation products [TpMe2 Y{η2 -(C,N)-CH(SiHR2 )Si(Me2 )NSiMe3 }] (R=Ph (4 b); R=Et (4 c)). The equimolar reaction of 1TpMe2 with PhSiH3 also produced the mono C-H activation product 4 a ([TpMe2 Y{η2 -(C,N)-CH(SiH2 Ph)Si(Me2 )NSiMe3 }(thf)]). A study of their reactivity showed that4 a facilely reacted with 2 equivalents of benzothiazole by an unusual 1,1-addition of the C=N bond of the benzothiazolyl unit to the Si-H bond to give the C-H/Si-H cross-dehydrocoupling product [(TpMe2 )Y{η3 -(N,N,N)-N(SiMe3 )SiMe2 CH2 Si(Ph)(CSC6 H4 N)(CHSC6 H4 N)}] (5). These results indicate that this modification endows the silylamino ligand with novel reactivity.

Regioblock copolymers of single alkenes hold great promise for modifying the properties of polymer materials but remain scarce due to the lack of viable synthetic methodologies. Here we describe a method for switching the regioselectivity of the cationic yttrium-catalyzed polymerization of conjugated dienes during chain growth, which leads to the formation of a series of di- and multiregioblock homo/mixed-copolymers with different properties from isoprene and myrcene. Mechanistic data demonstrate that the amidinate yttrium active species [LbYPIP3,4]+ (Lb = [PhC(NC6H4iPr2-2,6)2]−) changes to the tetramethylaluminate yttrium active center {LsYPIP3,4}+ (Ls = [AlMe4]−) in situ by amidinate ligand transfer in the presence of AlMe3. The transformation of active species switches the regioselectivity from 3,4- to cis-1,4 polymerization while the polymer chain keeps propagating. AliBu3 not only functions as a chain transfer agent but also plays a key role in preventing the chain termination during the amidinate tr...

An efficient method for preparation of substituted 6H-isoindolo[2,1-a]indol-6-ones (2) that are important structural components of a vast array of naturally occurring and pharmacologically active compounds, has been developed by the palladium-catalyzed intramolecular cycloaminocarbonylation of 2-(1H-indol-2-yl)phenyl tosylates with CO. Significantly, the intermolecular aminocarbonylation products 2-(1H-indol-2-yl)benzamides are formed when an excess of amine is used in this reaction system. Alternatively, 2-(1H-indol-2-yl)benzamides can also be synthesized by the in situ aminolysis of 2. Furthermore, treatment of 2 with hydrosilane in the presence of KOH gave the unprecedented reducing products 2-(-1H-indol-2-yl)benzyl alcohols in 75–86% yields. These results demonstrate that 6H-isoindolo[2,1-a]indol-6-ones are versatile substrates for further synthetic elaboration.

Direct N–H addition of amidines to alkenes is a highly valuable but challenging transformation that remains elusive. Now, the intramolecular hydroamidination of N-alkenylamidines is achieved by using a rare earth catalyst, which provides an efficient and atom-economical approach for substituted imidazolines and tetrahydropyrimidines. Moreover, a mild and efficient method for the catalytic degradation of amidines to give amines and nitriles is also developed. Additionally, amidine reconstruction followed by an intramolecular alkene hydroamidination strategy for the synthesis of substituted imidazolines and tetrahydropyrimidines from secondary enamines and inactive amidines has also been established, which may circumvent the need for some unavailable starting materials. The mechanistic studies prove that these reactions proceed via a key lanthanide amidinate intermediate that can undergo substrate- and amine-controlled chemodivergent transformations: intramolecular alkene insertion, nitrile extrusion, amidinate reconstruction, or a combination of the reactions. The results presented here not only demonstrate the synthetic potential and versatility of alkene hydroamidination with substrates, but also provide a good insight into the factors that promote or deter the hydroamidination of alkenes.

The mixed mono- and dianionic β-diketiminato yttrium complex [η2-N,N-{N(2,6-iPr2C6H3)C(Me)}2CH]Y[η2-N,N-N(2,6-iPr2C6H3)C(Me)CHC(═CH2)N(C6H3-iPr2-2,6)] (1) was synthesized in almost quantitive yield by the metathesis reaction of β-diketiminato potassium with YCl3 in a 3:1 molar ratio in THF at room temperature. Complex 1 reacted with 1 equiv of KCH2Ph under the same conditions to afford a linear dianionic β-diketiminato-supported Y(III)/K(I) heterobimetallic polymer {Y[μ-η2:η1-N,N-N(2,6-iPr2C6H3)C(Me)CHC(═CH2)N(C6H3-iPr2-2,6)]2-K(THF)3}∞ (2). Moreover, 2 can be transformed into the corresponding salt-type complexes [K([2.2.2]cryptand)]+{[η2-N,N-N(2,6-iPr2C6H3)C(Me)CHC(═CH2)N(C6H3-iPr2-2,6)]2Y}− (3) and [nBn4N]+{[η2-N,N-N(2,6-iPr2C6H3)C(Me)CHC(═CH2)N(C6H3-iPr2-2,6)]2Y}− (4) in high yields by the reactions of 2 with [2,2,2]-cryptand or nBu4NCl in THF, respectively. The reaction of 3 and 4 with 2 equiv of CS2 in THF at amibent temperature gave the anionic or neutral aryl-substituted dihydropyridinethione [K([...

A series of guanidinate rare-earth metal complexes [(PhCH2)2NC(NC6H4iPr2-2,6)2]RE(CH2C6H4NMe2-o)2 (RE = Y (2a), La (2b), Dy (2c), Lu (2d)) were synthesized by the acid–base reaction of RE(CH2C6H4NMe2-o)3 with (PhCH2)2N[C(NHR)(NR)] (R = 2,6-iPr2-C6H3) (1) in THF. Treatment of complexes 2 with two equivalents of carbon dioxide, sulfur and phenyl isothiocyanate gave the corresponding insertion products {[(PhCH2)2NC(NC6H4iPr2-2,6)2]RE(μ-η2:η1-O2CCH2C6H4NMe2-o)(μ-η1:η1-O2CCH2C6H4NMe2-o)}2 (RE = Y (3a), La (3b), Dy (3c), Lu (3d)), {[(PhCH2)2NC(NC6H4iPr2-2,6)2]RE[μ-S(CH2C6H4NMe2-o)]2}2 (RE = Y (4a), La (4b), Dy (4c), Lu (4d)) and {[(PhCH2)2NC(NC6H4iPr2-2,6)2]RE{SC(CH2C6H4NMe2-o)NPh}2 (RE = Y (5a), La (5b), Dy (5c), Lu (5d)) in good yields, respectively. All new complexes were fully characterized by NMR spectroscopy and elemental analysis. The structures of 1, 2d, 3, 4a, 4c–d, 5a, and 5c–d were established by X-ray diffraction studies. Complexes 2 were found to have a high activity and excellent 3,4-selectivity for isoprene polymerization in the presence of [Ph3C][B(C6F5)4].

The palladium-catalyzed three-component cycloaminocarbonylation of 2 -formylaryl tosylates with hydrazines and carbon monoxide has been established, which provides an efficient method for synthesis of substituted phthalazinones. In addition, by applying this protocol as the key step, Hydralazine can easily be synthesized in 65% yield.

The rare-earth-metal organic cyclo-P

Lanthanide-catalyzed alkynyl exchange through C-C single-bond cleavage assisted by a secondary amino group is reported. A lanthanide amido complex is proposed as a key intermediate, which undergoes unprecedented reversible β-alkynyl elimination followed by alkynyl exchange and imine reinsertion. The in situ homo- and cross-dimerization of the liberated alkyne can serve as an additional driving force to shift the metathesis equilibrium to completion. This reaction is formally complementary to conventional alkyne metathesis and allows the selective transformation of internal propargylamines into those bearing different substituents on the alkyne terminus in moderate to excellent yields under operationally simple reaction conditions.

International audience; The preferential substitution of oxo ligands over alkyl ones of rare-earth complexes is commonly considered as "impossible" due to the high oxophilicity of metal centers. Now, it has been shown that simply assembling mixed methyl/oxo rare-earth complexes to a rigid trinuclear cluster framework cannot only enhance the activity of the Ln-oxo bond, but also protect the highly reactive Ln-alkyl bond, thus providing a previously unrecognized opportunity to selectively manipulate the oxo ligand in the presence of numerous reactive functionalities. Such trimetallic cluster has proved to be a suitable platform for developing the unprecedented non-redox rare-earth-mediated oxygen atom transfer from ketones to CS2 and PhNCS. Controlled experiments and computational studies shed light on the driving force for these reactions, emphasizing the importance of the sterical accessibility and multimetallic effect of the cluster framework in promoting reversal of reactivity of rare-earth oxo complexes.

International audience; Reactions of trinuclear rare-earth metal complexes bearing functionalized phosphinidene ligand [L(3)Ln(3)(mu(2)-Me)(2)(mu(3)-Me) (mu(3)-eta(1): eta(2):eta(2)-PC6H4-o) (L = [PhC((NC6H4Pr2)-Pr-i-2,6)(2)](-), Ln = Y (la), Lu (lb)) with phenylacetylene, CO2, diisopropyl carbodiimide, isocya-nide, or PhSSPh lead to the formation of a series of phosphorus-containing products. The reaction of 1 with CS2 yields two novel P-methyl-phosphindole-2,3-dithio-late dianion complexes, revealing an unusual tandem desulfurization/coupling/cyclization reaction mode of CS2. A possible reaction pathway was determined by density functional theory calculations. This emphasizes the key role of the reduction power of the formal P2- part of the phosphinidene in the C-S bond cleavage.

The first catalytic cycloamidination of aminoalkenes with nitriles has been achieved by using rare-earth complexes. This reaction is equivalent to the desired intramolecular hydroamination of alkenylamidines, and allows a new direct access to substituted 2-imidazolines and tetrahydropyrimidines in high yields under operationally simple reaction conditions. Moreover, the methodology is also efficient for synthesis of symmetric and unsymmetric bridged diimidazolines. Compared with the traditional stepwise-mediated synthetic approaches, the present method avoids the use of additives and harsh reaction conditions, and thus leads to a completely different product distribution. Mechanistic data suggest that the reaction involves the initial NH activation by lanthanide complex followed by nitrile insertion into a Ln-N bond to form an amidinate lanthanide intermediate which undergoes the cyclization.

The palladium-catalyzed cycloaminocarbonylation of 2-(aminomethyl)aryl tosylates with CO has been established, by which a variety of salicylaldehyde derived 2-(aminomethyl)aryl tosylates may be cyclocarbonylated in the presence of CO, to afford the corresponding substituted isoindolinones in moderate to excellent yields. Furthermore, the method is also effective for the synthesis of isoindoline-1,3-diones and 2-alkyl-1H-benzo[e]isoindol-3(2H)-ones from 2-(N-alkylcarbamoyl)aryl tosylates and 1-(aminomethyl)naphthalene-2-yl tosylates, respectively.

A simple, cheap, efficient, and metal-free method for one-step synthesis of a library of 1,3-diheteroatom five-membered heterocycles with exocyclic C N and C C double bonds was presented. The convenient reactions proceed via the direct three-component halocyclization of propargylamines, heterocumulenes and I2 (NBS).

The reactions of β-diketiminatoyttrium dialkyl complex LY(CH2Ph)2(THF) (1, L = [{N(2,6-iPr2C6H3)C(Me)}2CH]−) with a series of aromatic N-heterocycles such as 2-phenylpyridine, benzothiazole, and benzoxazole were studied and displayed discrete reactivity including C–H activation, C–C coupling, ring-opening/insertion, and dearomatization. The reaction of 1 with 2-phenylpyridine in 1:2 molar ratio in THF at 30 °C for 14 days afforded a structurally characterized metal complex, LY(η2-N,C-C5H4NC6H4-2)[C5H4N(CH2Ph-4)Ph] (2), in 73% isolated yield, indicating the occurrence of phenyl ring C(sp2)–H activation and pyridine ring 1,4-addition/dearomatization. However, when this reaction was done at 5 °C for 7 days, it gave the pyridine ring 1,2-addition product LY(η2-N,C-C5H4NC6H4-2)[C5H4N(CH2Ph-2)Ph] (3) in 54% isolated yield. Further investigations revealed that complex 2 is the thermodynamic controlled product and complex 3 is the kinetically controlled product; 3 converted slowly into 2, as confirmed by 1H NMR s...

Treatment of the yttrium dialkyl complex TpMe2Y(CH2Ph)2(THF) (TpMe2 = tri(3,5 dimethylpyrazolyl)borate, THF = tetrahydrofuran) with S8 in a 1:1 molar ratio in THF at room temperature afforded a yttrium pentasulfide TpMe2Y(κ4-S5) (THF) (1) in 93% yield. The yttrium monoalkyl complex TpMe2CpYCH2Ph(THF) reacted with S8 in a 1:0.5 molar ratio under the same conditions to give another yttrium pentasulfide [(TpMe2)2Y]+[Cp2Y(κ4-S5)]− (10) in low yield. Further investigations indicated that the S52– anion facilely turned into the corresponding thioethers or organic disulfides, and released the redundant S8, when it reacted with some electrophilic reagents. The mechanism for the formation of the S52– ligand has been investigated by the controlling of the reaction stoichiometric ratios and the stepwise reactions.

A high-efficiency and atom-economic route for the synthesis of N-aryl-substituted propiolamidines was established through the addition of terminal alkynes with aryl-substituted symmetrical or unsymmetrical carbodiimides catalyzed by mixed TpMe2/Cp rare-earth-metal alkyl complexes (TpMe2)CpLnCH2Ph(THF) (1Ln). Moreover, the gadolinium alkyl complex 1Gd can also serve as a catalyst for the double addition of dialkynes with carbodiimides. Mechanism studies indicated that the variable coordination modes (κ3 or κ2) of the TpMe2 ligand on the rare-earth-metal species may play an important role in the catalytic cycles.

La[N(SiMe3)2]3 proves to be an efficient catalyst system for the cyclocarbonylation of 1,2-disubstituted benzenes with isocyanates. In this approach, aryl/alkyl isocyanates react with o-phenylenediamine, o-aminophenol, o-aminothiophenol, catechols and anilines ortho-substituted by CH2NH2 and CONH2 to form, respectively, the corresponding benzimidazolones, benzoxazolones, benzothiazolones, benzodioxolones, 3,4-dihydroquinazolin-2(1H)-one, and quinazolinediones. These results represent the first example of lanthanide-catalyzed carbonylation. This methodology is also applicable for the preparation of various benzannulated 1,3-diheteroatom cyclic thioketones starting from aryl/alkyl isothiocyanates or CS2 in good to excellent yields. Based on the results of experiments performed using an o-aminobenzamido dianion lanthanide complex, a general mechanism, involving the tandem reaction of two lanthanide-ligand bonds with one heterocumulene molecule, is proposed as well.

The McMurry-type olefinations have become a powerful tool in organic synthesis. However, the use of stoichiometric amounts of unmanageable Ti species and the generation of a large amount of salts limit their applications on the industrial scale. This paper outlines a simple and practical catalytic electron transfer (ET) system composed of TiCl4 and Yb, which turned out to be effective for homo- and cross-deoxygenative coupling of aldehydes and ketones. Specifically, the method is based upon the strategy that the low valent Ti species abstracts oxygen from carbonyl and delivers them to highly oxophilic Yb in an unprecedented manner. Remarkably, the present process is operationally simple, minimizes the generation of chemical waste, and makes the only by-product Yb2O3 as a solid easily removed and utilized; furthermore, the yield improved significantly of that obtained in the stoichiometric version in our system. Our mechanistic data not only provide the direct evidence that Ti(IV) can facilitate the part deoxygenation of pinacol at room temperature, but also demonstrate, for the first time, that for bulky ketones the turnover-limiting step is the Ti-mediated carbonyl coupling rather than the subsequent deoxygenation of the resulting pinacolate intermediates, which are different from the previous observations.

Iron-catalyzed direct reduction of allylic halides with benzylic alcohol was achieved, providing a new, simple, and efficient method for conducting highly regioselective hydrodehalogenation. This method not only features a readily available reductant, an inexpensive catalyst, simple manipulation, and good tolerance of functional groups including nitriles, nitro, esters, and methoxyl groups, it also has mild reaction conditions and shows complete regioselectivity in that only halides sited at the allylic position are reduced. Alternatively, this method can be applied in the selective transformation of benzylic alcohols to aromatic aldehydes without overoxidation to carboxylic acids.

Unusual chemical transformations such as three-component combination and ring-opening of N-heterocycles or formation of a carbon-carbon double bond through multiple C-H activation were observed in the reactions of Tp(Me2) -supported yttrium alkyl complexes with aromatic N-heterocycles. The scorpionate-anchored yttrium dialkyl complex [Tp(Me2) Y(CH2 Ph)2 (THF)] reacted with 1-methylimidazole in 1:2 molar ratio to give a rare hexanuclear 24-membered rare-earth metallomacrocyclic compound [Tp(Me2) Y(μ-N,C-Im)(η(2) -N,C-Im)]6 (1; Im=1-methylimidazolyl) through two kinds of C-H activations at the C2- and C5-positions of the imidazole ring. However, [Tp(Me2) Y(CH2 Ph)2 (THF)] reacted with two equivalents of 1-methylbenzimidazole to afford a C-C coupling/ring-opening/C-C coupling product [Tp(Me2) Y{η(3) -(N,N,N)-N(CH3 )C6 H4 NHCHC(Ph)CN(CH3 )C6 H4 NH}] (2). Further investigations indicated that [Tp(Me2) Y(CH2 Ph)2 (THF)] reacted with benzothiazole in 1:1 or 1:2 molar ratio to produce a C-C coupling/ring-opening product {(Tp(Me2) )Y[μ-η(2) :η(1) -SC6 H4 N(CHCHPh)](THF)}2 (3). Moreover, the mixed Tp(Me2) /Cp yttrium monoalkyl complex [(Tp(Me2) )CpYCH2 Ph(THF)] reacted with two equivalents of 1-methylimidazole in THF at room temperature to afford a trinuclear yttrium complex [Tp(Me2) CpY(μ-N,C-Im)]3 (5), whereas when the above reaction was carried out at 55 °C for two days, two structurally characterized metal complexes [Tp(Me2) Y(Im-Tp(Me2) )] (7; Im-Tp(Me2) =1-methyl-imidazolyl-Tp(Me2) ) and [Cp3 Y(HIm)] (8; HIm=1-methylimidazole) were obtained in 26 and 17 % isolated yields, respectively, accompanied by some unidentified materials. The formation of 7 reveals an uncommon example of construction of a CC bond through multiple C-H activations.

Two new trinuclear μ3 -bridged rare-earth metal phosphinidene complexes, [{L(Ln)(μ-Me)}3 (μ3 -Me)(μ3 -PPh)] (L=[PhC(NC6 H4 iPr2 -2,6)2 ](-) , Ln=Y (2 a), Lu (2 b)), were synthesized through methane elimination of the corresponding carbene precursors with phenylphosphine. Heating a toluene solution of 2 at 120 °C leads to an unprecedented ortho CH bond activation of the PhP ligand to form the bridged phosphinidene/phenyl complexes. Reactions of 2 with ketones, thione, or isothiocyanate show clear phospha-Wittig chemistry, giving the corresponding organic phosphinidenation products and oxide (sulfide) complexes. Reaction of 2 with CS2 leads to the formation of novel trinuclear rare-earth metal thione dianion clusters, for which a possible pathway was determined by DFT calculation.

Three kinds of solvated lithium amidinates with different coordination models were obtained via recrystallization of (PhC(NC6H4 i Pr2- 2,6)2)Li(THF) (1a )i n different solvents. Treatment of o-Me2NC6H4CH2Li with LLnCl2(THF)n (2; L = (PhC(NC6H4 i Pr2-2,6)2) � (NCN dipp ), (o-Me2NC6H4CH2C- (NC6H4 i Pr2-2,6)2) � (NCN dipp ')) formed in situ from reaction of LnCl3(THF)x with LLi(THF) gave the rare-earth-metal bis(aminobenzyl) complexes LLn- (CH2C6H4NMe2-o)2 (L = NCN dipp , Ln = Sc (3a), Y (3b), Lu (3c); L = NCN dipp ', Ln = Sc (3d), Lu (3e)) in high yields. Reactions of complexes 3 with CO2, PhNCO, 2,6-diisopropylaniline, and S have been explored. CO2 inserted into each LnC bond of complexes 3ac to form the dual-core complexes ((NCN dipp )Sc(μ- η 1 :η 1 -O2CCH2C6H4NMe2-o)2)2 (4a )a nd ((NCN dipp )Ln(μ-η 1 :η 2 - O2CCH2C6H4NMe2-o)(μ-η 1 :η 1 -O2CCH2C6H4NMe2-o))2 (Ln = Y (4b), Lu (4c)). The reaction of 3b,c,e with PhNCO produced LLu(OC(CH2C6H4NMe2- o)NPh)2(thf) (L = NCN dipp ,L n =Y( 5b), Lu (5c); L = NCN dipp ', Ln = Lu (5e)). Protonolysis of 3a,b by 2,6-diisopropylaniline formed straightforwardly the μ2-imido complexes ((NCN dipp )Ln(μ-NC6H4 i Pr2- 2,6))2 (Ln = Sc (6a), Lu (6c)). Reaction of 3e with S8 afforded the sulfur insertion products (NCN dipp ')Lu(CH2C6H4NMe2- o)(SCH2C6H4NMe2-o)(thf) (7e) and (NCN dipp ')Lu(SCH2C6H4NMe2-o)2(thf)2 (7f) in high yields, respectively, depending on the stoichiometric ratio. All of these complexes were fully characterized by elemental analysis, NMR spectroscopy, and X-ray structural determinations.

The TpMe2-supported yttrium dialkyl TpMe2Y(CH2Ph)2(THF) (TpMe2 = tri(3,5-dimethylpyrazolyl)borate) reacted with 1 equiv of ArNH2 in THF at room temperature to afford the yttrium alkyl primary amido complexes TpMe2YNHAr(CH2Ph)(THF) (Ar = Ph (1), C6H3-iPr2-2,6 (2)) in 84% and 88% isolated yields, respectively. Complex 1 reacted with iPrN═C═NiPr in THF at room temperature to give a yttrium dianionic guanidinate complex, TpMe2Y[(iPrN)2C═NPh](THF)2 (3, 74%). However, the reaction of 1 with ArN═C═NAr (Ar = C6H3-iPr2-2,6) in the same conditions produced a Y–C bond insertion product, TpMe2Y[(ArN)2CCH2Ph](NHPh) (4, 87%). Moreover, treatment of 2 with 1 equiv of iPrN═C═NiPr in THF at room temperature afforded two yttrium complex, TpMe2Y[(iPrN)C═NAr](THF) (5) and TpMe2Y[(iPrN)2CCH2Ph](NHAr) (6), in 58% and 19% isolated yields, respectively. These results indicated that carbodiimide can selectively insert into the Y–CH2Ph and Y–NHAr σ-bonds of TpMe2-supported yttrium alkyl primary amido complexes TpMe2YNHAr(CH2Ph)(TH...

The first catalytic cycloamidination of aminoalkenes with nitriles has been achieved by using rare-earth complexes. This reaction is equivalent to the desired intramolecular hydroamination of alkenylamidines, and allows a new direct access to substituted 2-imidazolines and tetrahydropyrimidines in high yields under operationally simple reaction conditions. Moreover, the methodology is also efficient for synthesis of symmetric and unsymmetric bridged diimidazolines. Compared with the traditional stepwise-mediated synthetic approaches, the present method avoids the use of additives and harsh reaction conditions, and thus leads to a completely different product distribution. Mechanistic data suggest that the reaction involves the initial NH activation by lanthanide complex followed by nitrile insertion into a Ln-N bond to form an amidinate lanthanide intermediate which undergoes the cyclization.

The palladium-catalyzed cycloaminocarbonylation of 2-(aminomethyl)aryl tosylates with CO has been established, by which a variety of salicylaldehyde derived 2-(aminomethyl)aryl tosylates may be cyclocarbonylated in the presence of CO, to afford the corresponding substituted isoindolinones in moderate to excellent yields. Furthermore, the method is also effective for the synthesis of isoindoline-1,3-diones and 2-alkyl-1H-benzo[e]isoindol-3(2H)-ones from 2-(N-alkylcarbamoyl)aryl tosylates and 1-(aminomethyl)naphthalene-2-yl tosylates, respectively.

The mixed TpMe2/Cp-supported yttrium monoalkyl (TpMe2)CpYCH2Ph(THF) (1) reacted with 1 equiv of PhCN in THF at room temperature to afford the imine–enamine tautomer (TpMe2)CpY(N(H)C(Ph)═CHPh)(THF) (2) and the insertion product (TpMe2)CpY(N═C(CH2Ph)Ph)(THF) (3), in 61% and 12% isolated yields, respectively. 2 further reacted with PhCN in toluene at 120 °C to give the N–H bond addition product (TpMe2)CpY(N(H)C(Ph)NC(Ph)═CHPh) (4). Treatment of 1 with 1 equiv of anthranilonitrile produced the dimer [(TpMe2)CpY(μ-NHC6H4CN)]2 (5). The monomer product (TpMe2)CpY(NHC6H4CN)(HMPA) (6) can be obtained through the coordination of HMPA (hexamethylphosphoric triamide). The reaction of 5 with 1 in THF at room temperature gave the cyano group insertion product [(TpMe2)CpY(THF)]2(μ-NHC6H4C(CH2Ph)═N) (7). However, this reaction under the heating conditions gave an unexpected rearrangement product, (TpMe2)CpY(THF)(η2-NHC6H4C(CH2Ph)═NH) (8). 5 further reacted with o-aminobenzonitrile at 120 °C to afford the nucleophilic add...

The FeCl3-promoted annulation reaction of aryl acetaldehydes with alkynes has been established, which provides a new and versatile straightforward procedure for the regioselective synthesis of mono-, di-, and polysubstituted naphthalenes under mild conditions. Interestingly, the present catalytic system not only differentiates between internal and terminal alkynes but also shows unprecedented complete Me3SiOH elimination selectivity for silyl alkyne substrates. Furthermore, the synthesis of a series of substituted phenanthrenes via reactions of nathphyl acetaldehydes with internal alkynes is also achieved for the first time in good yields with excellent regioselectivity.

Reported herein is the FeCl3-promoted intermolecular sulfoesterification of o-(1-alkynyl)benzoates with disulfides, which provides a convenient and efficient method for synthesis of 4-sulfenylisocoumarins. Various functional groups such as methoxy, halides, ester, cyano and silicon groups in the substrates are tolerated, and heterocycle-fused chalcogenylpyrones are also successfully achieved directly from the corresponding heterocyclic precursors under the same reaction conditions. In addition, starting from diynylbenzoate, this reaction sequence can be combined with a bicyclization step leading to the tetracyclic (E)-3-(2-phenyl-3-phenylchalcogenylinden-1-ylidene)isobenzofuranone frameworks with high regiospecificity and exclusive trans stereoselectivity.