Regiodivergent Switchable N1- and C3-Alkylation of Indoles with Grignard Reagents Based on Umpolung Strategy.

Enantioenriched molecules bearing indole-substituted stereocenters form a class of privileged compounds in biological, medicinal, and organic chemistry. Thus, the development of methods for asymmetric indole alkylation is highly valuable in organic synthesis. Traditionally, achieving N-selectivity in indole alkylation reactions is a significant challenge, since there is an intrinsic preference for alkylation at C3, the most nucleophilic position. Furthermore, selective and predictable access to either N- or C3-alkylated chiral indoles using catalyst control has been a long-standing goal in indole functionalization. Herein, we report a ligand-controlled regiodivergent synthesis of N- and C3-alkylated chiral indoles that relies on a polarity reversal strategy. In contrast to conventional alkylation reactions in which indoles are employed as nucleophiles, this transformation employs electrophilic indole derivatives, N-(benzoyloxy)indoles, as coupling partners. N- or C3-alkylated indoles are prepared with high levels of regio- and enantioselectivity using a copper hydride catalyst. The regioselectivity is governed by the use of either DTBM-SEGPHOS or Ph-BPE as the supporting ligand. Density functional theory (DFT) calculations are conducted to elucidate the origin of the ligand-controlled regiodivergence.

Enantioenriched molecules bearing indole-substituted stereocenters form a class of privileged compounds in biological, medicinal, and organic chemistry. Thus, the development of methods for asymmetric indole alkylation is highly valuable in organic synthesis. Traditionally, achieving N-selectivity in indole alkylation reactions is a significant challenge, since there is an intrinsic preference for alkylation at C3, the most nucleophilic position. Furthermore, selective and predictable access to either N- and C3-alkylated chiral indoles using catalyst control has been a long-standing goal in indole functionalization. Herein, we report a ligand-controlled regiodivergent synthesis of N- and C3-alkylated chiral indoles that relies on a polarity reversal strategy. In contrast to conventional alkylation reactions in which indoles are employed as nucleophiles, this transformation employs electrophilic indole derivatives, N-(benzoyloxy)indoles, as coupling partners. N- or C3-alkylated indoles are prepared with high levels of regio- and enantioselectivity using a copper hydride catalyst. The regioselectivity is governed by the use of either DTBM-SEGPHOS or Ph-BPE as the supporting ligand. Density functional theory (DFT) calculations are conducted to elucidate the origin of the ligand-controlled regiodivergence.

Carbon-carbon bond forming reactions are among the most important and useful methods for organic synthesis. During the last years, significant progress has been made in this field. Whereas many catalysts were developed for the coupling of aryl, alkenyl, and alkynyl halides, non-activated alkyl halides remain challenging substrates, mainly due to unproductive β-hydride elimination and difficulty in oxidative addition of alkyl halides. This dissertation is devoted to the development of a well-defined nickel catalyst for cross coupling of non-activated alkyl halides and direct alkylation of C–H bonds. Chapter 2 describes the synthesis of a new pincer MeN2N ligand and its Ni complexes. This ligand can be obtained by Pd-catalyzed C–N coupling of 2-amino-N,N-dimethylaniline and 2-bromo-N,N-dimethylaniline. Reaction of its Li salt with Ni(dme)Cl2 gives [(MeN2N)Ni-Cl] (1). Complex 1 can be akylated with Grignard reagents to give [(MeN2N)Ni-Alkyl] species. Stability of the alkyl complexes against β-hydride elimination inspired us to use the [(MeN2N)Ni-Cl] complex as a catalyst for cross coupling of carbon nucleophiles with alkyl halides. After investigating different experimental conditions, we found that complex 1 is an active catalyst for cross coupling of non-activated alkyl polyhalides (Chapter 3) and alkyl monohalides (Chapter 4) with alkyl Grignard reagents. The reaction with alkyl monohalides can be done at -35 °C in DMA and only 30min is required to accomplish the formation of the desired products. The high activity of the catalyst resulted in a high group tolerance. Ester, ketone, amide, nitrile, heterocyclic, and acetal groups didn't pose problems. In Chapter 5, the catalysis was extended to include aryl and heteroaryl Grignard reagents as nucleophiles. The best results were obtained with primary alkyl bromides and iodides and cyclic secondary alkyl iodides in THF and at room temperature. Addition of an additive such as TMEDA or bis[2-(N,N-dimethylaminoethyl)]ether (O-TMEDA) was necessary to prevent the formation of undesired homocoupling products. Functionalized Grignard reagents could be readily coupled. The [(MeN2N)Ni-Cl] catalyst was then used for the Sonogashira coupling of alkyl halides with alkynes (Chapter 6). A wide range of functionalized alkyl halides could be used for this reaction. Not only alkyl iodides and bromides but also alkyl chlorides can be used. Moreover, by changing reaction conditions (additive and temperature), selective coupling of C–Br bond in the presence of C–Cl bond, and of C–I bond in the presence of both C–Br and C–Cl bonds can be achieved. This feature allowed us to carry out multiple and selective Sonogashira coupling of the substrates containing different alkyl halide bonds. We could combine Sonogashira coupling with Kumada-Corriu-Tamao coupling. Utilization of these two methods leads to a simple and rapid synthesis of organic molecules. Similar conditions were then applied for the direct alkylation of aromatic heterocycles in Chapter 7. Aromatic heterocyclic compounds are widely used as bio-active molecules, pharmaceuticals, and organic materials. Direct C–H functionalization represents the most straightforward way for the derivatization of these compounds. Despite of the developments during the last years, direct alkylation of C–H bond with alkyl halides is still challenging. Utilization of our [(MeN2N)Ni-Cl] catalyst gives the desired products in high yields and a wide range of aromatic heterocyclic compounds can be used for the reaction. The well-defined nature and a high stability of [(MeN2N)Ni-Cl] complex and its derivatives enabled us to perform detailed mechanistic investigations of the catalytic transformations. Presumed intermediates of catalytic cycles were determined and some of them were synthesized or separated from the reaction mixture. The resting states of the catalysts were also defined in most of the cases, giving important information for the mechanistic elucidation. In the last part (Chapter 8) we developed a direct C–H carboxylation chemistry for aromatic heterocycles. The carboxylation can be done under catalyst-free conditions and with a mild base Cs2CO3. The unstable carboxylic acids were converted to the more stable esters by a one-pot reaction with MeI. A wide substrate scope was achieved.

Conversion of a wide range of N-Boc amides to aryl ketones was achieved with Grignard reagents via chemoselective C(O)-N bond cleavage. The reactions proceeded under catalyst-free conditions with different aryl, alkyl, and alkynyl Grignard reagents. α-Ketoamide was successfully converted to aryl diketones, while α,β-unsaturated amide underwent 1,4-addition followed by C(O)-N bond cleavage to provide diaryl propiophenones. N-Boc amides displayed higher reactivity than Weinreb amides with Grignard reagents. A broad substrate scope, excellent yields, and quick conversion are important features of this methodology.

Reaction of (bromodifluoromethyl)phenyldimethylsilane with organometallic reagents

It has been established that dihalodiphosphinenickel(II) complexes exhibit extremely high catalytic activity for selective cross-coupling of Grignard reagents with aryl and alkenyl halides. This catalytic reaction can be employed in synthetic practice for reasons of simple procedures, mild reaction conditions, high yields and high purity of the coupling products, and the wide applicability to reactions involving primary and secondary alkyl (regardless of the presence or absence of β-hydrogen (s)), aryl, and alkenyl Grignard reagents and nonfused, fused, and substituted aromatic halides and haloolefins. Limitations lie in sluggish reactions between alkyl Grignard reagents and dihaloethylenes. The most effective catalysts are [Ni{(C6H5)2P(CH2)3P(C6H5)2}Cl2] for alkyl and simple aryl Grignard reagents, [Ni{(CH3)2P(CH2)2P(CH3)2}Cl2] for alkenyl and allylic Grignard reagents and [Ni{P(C6H5)3}2-Cl2] for sterically hindered aryl Grignard reagents and halides. Great stabilizing effects of phosphine ligands on the catalytic species are demonstrated by no effect observed after aging the catalyst. Organic chlorides are generally the most suitable halide in view of the reasonable reactivities and limited side reactions. Ether is favored over tetrahydrofuran as solvent. About sixty experimental results are presented and several features are discussed.

This article has no abstract. Keywords: preparation; hexamethyl-trans-σ-trishomobenzene (2); preparation; olefins from vinyl halides and alkyllithiums; beckmann fragmentation of ketoximes; aryl- and vinyl-substituted acetylenes; dehydrobromination of α-bromo ketones; ketone synthesis; extrusion of mercury from bis(propenyl)mercury; allylation of amines; alkenes from vinyl iodides and grignard reagents; conjugated enynes; arylalkynes; unsymmetrical biaryls and diarylmethanes; vinyl nitriles; cyclization via π-allylpalladium complexes; steroid side chain; cyclization to medium-sized lactones; chiral methyl chiral lactic acid (5); isomerization of 1,3-diene epoxides; alkylation of vinyl lactones; reductive acylation of alkoxy-substituted allylic acetates; methylenecyclopentanes; stereospecific synthesis of alkenes; cross-coupling of aryl halides and 1-alkenylboranes; iboga alkaloids; isomerization and elimination of allylic acetates; supported reagent; coupling of allyl bromides and allylstannanes; decarboxylation of β-acetoxy carboxylic acids; cleavage of endoperoxides; alkylation of dihydropyranyl acetates; alkylation and amination of allylic phosphates; 1,4-Dienes; α-Allylated ketones; alkylation of allyl nitroalkanes; allylation of nucleophiles; alkylation of vinyl epoxides; vinylsilanes; nucleophilic substitution reactions with α-acetoxy-β,γ-unsaturated nitriles; macrocyclization; macroheterocyclization; β-Keto esters; double silylation; allylic sulfones; 2,3-Disubstituted bicyclo[2.2.1]heptanes; desulfonylation; homoallylic alcohols; sequential π-allylpalladium alkylation; biaryls; 1,3-Dienes; heterosubstituted 1,3-dienes; 1,3-Diynes; allenynes; coupling of vinyl triflates with organotins; acylation of organozinc reagents; β-Carboline synthesis; allylation of potassium enoxyborates; allylic amination; macrocyclization by allylation–alkylation; steroidal 6β-hydroxy-2,4-diene-1-ones; trans- cis-Cinnamic acids; RX RCHO; coupling of vinyl triflates with alkenes; α-Diketones; carbonylation of 1-iodo-1,4- and -1,5-dienes; conjugate reduction; denitro-sulfonylation; allylic sulfones; coupling of 1-alkenylboranes with 1-bromoalkenes or -alkynes; cross-coupling of organoalanes with allylic acetals or ortho esters; carbonylation; 1,4-diazepines; decarbonylative cross coupling of acyl halides; decarbonylation of acyl cyanides; allylation of lithium 1-cyclopentenolates; asymmetric allylation; bisethynylation of vic-dichloroethylenes; pyrrolidines; piperidines; unsymmetrical biaryls; primary allylic amines; coupling of aryl triflates with organostannanes; coupling of vinylboranes and vinyl halides; intramolecular heck reactions; hydroxylamination; denitration of allylic nitro groups; coupling of RCOCl with Bu4Pb; intramolecular arylation; cyclizative heck coupling; [3 + 2]Annelation; Pd-catalyzed intramolecular ene reactions; allylidenation of aldehydes; 3-Aza-Cope rearrangement; biphenyls; coupling of alkylsilanes with aryl triflates; (Z,E)-2-Bromo-1,3-dienes; alkenyl sulfides; ArOTf+AlR3 ArR; 1,2-Diene-4-ynes; indole synthesis; sulfones; carbonylation of aryl and vinyl iodides; benzylpalladation; intramolecular heck cyclizations; intramolecular ene reactions; coupling of 1-alkynes and vinyl halides; coupling of 2-bromonaphthoquinones with stannanes; addition of (ArS)2 and (ArSe)2 to 1-alkynes; coupling of acid chloride with (E)-Bu3SnCH CHSnBu3; 1,4-diketones; chiral oxazolines; stille carbonylative coupling; cyclization of triynes to benzenes; coupling of aryl iodides and arylboronic acids; allylic substitutions; allylation of carbonyl compounds and imines; coupling of organozincs with aryl halides; coupling of organozincs with alkenyl halides; coupling involving organoborons; coupling of organotins with unsaturated halides; destannylative acylation; coupling of organosilanes with aryl halides; cyclopropanation of norbornene; intramolecular zinc-ene reaction; deallylation; stille coupling; suzuki coupling; other cross-couplings; carbonylations; allylic substitutions; rearrangements; cycloadditions; hydrogenation; allyl and propargyl group transfer; suzuki coupling; intramolecular coupling of phenols with haloarenes; stille coupling; other reactions of organostannanes; negishi coupling; carbonylative coupling; arenes from enynes and diynes; cyclization; rearrangement; allylic displacements; tandem coupling and cyclization; cyclizations and cycloadditions; addition to alkynes; acylations; stille coupling; suzuki coupling; other coupling reactions; rearrangements; addition reactions; substitution reactions; coupling reactions; acylation and allylation; 2-pyridylpyrroles; coupling reactions; decarboxylative transformations; allylation; cyclizations; additions; cycloadditions; deprotection; coupling reactions; heterocycle synthesis; cleavage of C—O bonds; cyclization; cycloaddition; aminocarbonylation; addition; substitution; coupling reactions; isomerization; tetrabutylammonium fluoride, TBAF; tetrabutylammonium difluorotriphenylsilicate; tetracarbonylhydridorhenium; titanocene bis(triethyl phosphite); trimethylsilyl trifluoromethanesulfonate

Recently, an azine NNN–Pd(II) nonpalindromic pincer complex is generated, and its application in acceptorless dehydrogenative coupling is explored. This article establishes the application of the same pincer complex in the borrowing hydrogen process (BHP). Herein, the selective synthesis of C3 alkylated indoles (CAIs) is reported. Remarkably, this catalyst enables the synthesis of bis(indolyl)methanes (BIMs) by tuning the reaction conditions using the same substrates. The control experiments and quantum chemical analysis suggest that C3 functionalization of indole involves BHP. The formation of BIMs is an additional advantage.

Efficient copper-catalyzed synthesis of C3-alkylated indoles from indoles and alcohols

A select few: Several prochiral enyne chlorides were employed as substrates in the title reaction using Grignard reagents as the alkylation reagents (see scheme; CuTC=copper(I) thiophenecarboxylate). Excellent 1,3 substitution regioselectivities and good to excellent enantioselectivities were obtained. The substrate scope is additionally extended to diene chlorides.

Alkyl- and arylpyridines and 2,2'-bipyridines are conventionally prepared by Minisci reactions of pyridines and transition metal-catalyzed coupling reactions of halopyridines. Herein, purple light-promoted radical coupling reactions of 2- or 4-bromopyridines with Grignard reagents in Et2O or a mixture of Et2O and tetrahydrofuran in regular glassware without the need for a transition metal catalyst were disclosed for the first time. Methyl, primary and secondary alkyl, cycloalkyl, aryl, heteroaryl, pyridyl, and alkynyl Grignard reagents were compatible with the protocol. As a result, alkyl- and arylpyridines and 2,2'-bipyridines were easily prepared. Single electron transfer from the Grignard reagent to bromopyridine was stimulated by purple light. An electron extruded from the dimerization of the Grignard reagent worked as the catalyst. Light on/off experiments indicated that constant irradiation was required for product formation. Studies of radical clock substrates verified the involvement of a pyridyl radical from bromopyridine and the noninvolvement of an alkyl or aryl radical from the Grignard reagent. The available proof supports a photoinduced SRN mechanism for the new coupling reactions.

The goal of this thesis is to develop new carbon-carbon bond forming reactions using inexpensive and simple coupling partners like aryl halides (pseudohalides), sulfonyl derivatives, Grignard reagents, alkenes and alkynes with metal catalysis, preferably under environmental friendly conditions. A brief review of different cross-coupling reactions is presented applying noble metal catalysts like palladium and nickel. The importance of sustainability and hence the development of alternative iron-catalysis is discussed. The history of iron-catalyzed cross-coupling reactions and their applications to the synthesis of natural products, significant new developments in the field are visited. On our side, we have shown that 2-methylpropene-, prop-2-ene-, 1-methylprop-2-ene- and but-2-enesulfonyl chlorides can be used as electrophilic partners in palladium-catalyzed desulfinylative C-C cross-coupling reactions with both hard and soft nucleophiles. Alk-2-enesulfonate esters can also be used as electrophilic partners in allylic arylations and allylic alkylations. The regioselectivity of the reaction depends on the nature of the catalyst. With PdCl2(PhCN)2, (E)-crotylderivatives are formed with high regioselectivity using either 1-methylprop-2-ene- or but-2-enesulfonyl chlorides. We found also the alk-2-enesulfonyl chlorides that are electrophilic partners in palladium-catalyzed C-C coupling reactions can also be used as nucleophilic partners towards carbonyl compounds by Umpolung. In the presence of a catalytic amount of palladium and a transmetallating agent such as diethylzinc, sulfonyl chlorides can be coupled both with aldehydes and ketones to form homoallylic alcohols in good yields. In the case of unsymmetrical sulfonyl chlorides, regioselectivity depends on the polarity of the solvent and generates selectively products of γ-addition. Most useful is our discovery of conditions permitting the desulfinylative C-C cross-coupling of inexpensive alkanesulfonyl chlorides and Grignard reagents. Above 65 °C, the iron-catalyzed reaction generates products of C-C coupling rather than sulfones. It does not require any expensive and/or toxic ligand. This procedure was also applied to the ligand free iron-catalyzed couplings of alk-2-enesulfonyl chlorides with aromatic and aliphatic Grignard reagents. We have also discovered the synergic effect of iron and copper salts in palladium-free Sonogashira-Hagihara cross-coupling reaction of a wide range of aryl iodides, aromatic and aliphatic alkynes. Together with Dr. R. Loska we have studied the iron-catalyzed Mizoroki-Heck cross-coupling reaction with styrenes. In the presence of iron(II) chloride and potassium tert-butoxide in dimethyl sulfoxide, aryl and heteroaryl iodides undergo stereoselective Mizoroki–Heck C-C cross-coupling reactions with electron-rich alkenes at 60 °C giving the corresponding (E)-alkenes. The best yields were obtained upon addition of a ligand such as proline or picolinic acid. Aryl bromides and pyridinyl bromides are also coupled with styrenes but in lower yields. Finally, we have explored iron-catalyzed C-H activation. Ligand and solvent free-conditions have been developed for the iron-catalyzed oxidative C-C cross-coupling of tertiary amines and terminal alkynes. FeCl2 catalyzes the coupling to generate propargylamines using tert-butylperoxide as oxidant. High chemoselectivity was observed for the aminomethyl group and was attributed to a steric factor.

N-Boc- and N-ethoxycarbonyl-4-pyridones and the resulting 2,3-dihydropyridones undergo 1,4-addition reactions with Grignard reagents in the presence of chlorotrimethylsilane (TMSCl) or BF3·Et2O in excellent yields. Copper catalysis is not required, and mechanistic considerations suggest that the reaction is proceeding by a conjugate addition pathway rather than by a pathway involving 1,2-addition to an intermediate pyridinium ion. TMSCl-mediated conjugate addition of Grignard reagents to 2-substituted-2,3-dihydropyridones gives the trans-2,6-disubstitued piperidinones stereoselectively, while cuprate reagents give either the trans or cis diastereomers or mixtures.

This article has no abstract. Keywords: wolff rearrangement (arndt-eistert reaction); grignard reaction; intramolecular diazo olefin cyclization; allenic alcohols; phloroglucinol; alkenes; vinylsilanes; copper dienolates of α,β-unsaturated acids; β-Ketophosphonates; copper enolates of esters; alkylation of allylic grignard reagents; alkylation of nitroarenes; reaction of grignard reagents with epoxides; copper dienolate of a β,γ-unsaturated acid; exaltolide; optically active allylic alcohols and homoallylic epoxides; indoles; isoquinolines; CI-catalyzed reactions of RLi and RMgX; alkylation of 1-alkynes; cyclopropanation of allyl α-diazoalkanoates; RX RCF3; arylation of active methylene compounds; coupling of alkynes with organoiodides; sulfones; cross-coupling of organostannanes; conjugate additions; arylations; alkynes; 1,2-bis(trifluoromethyl)alkenes; alkynyl ketones; cyclization; desilylallylation; arylations; exchange reactions; allylic displacements; coupling reaction; arylations; substitution and coupling reactions; propargylic amines; rearrangement; baeyer–villiger oxidation; deoxygenation; coupling reactions; amidine synthesis; heterocycles; addition reactions; substitution; coupling reactions; addition; heterocycles; reduction and carboxylation; coupling reaction; (Catecholatoboryl)triethylammonium tetrachloroaluminate; enantioselective halogenation; synthetic chiral ligands; chromium – carbene complexes

The reactivity of a series of cationic metal (Os, Ru) vinylidene complexes containing the cyclopentadienyl(phosphine) and pentamethylcyclopentadienyl (phophine) ligand sets are discussed. The cationic metal vinylidene complexes 2 are prepared by alkylation reactions of alkyl halides with acetylide complexes (η5-C5R5)(PPh3)2M-C≡CR1 (1, M = Os, R = H, R1 = Ph; 1', M = Os, R = Me, R1 = Ph; 1a, M = Ru, R = H, R1 = Me; 1b, M = Ru, R = H, R1 = n-Bu). Complexes 2 react with n-Bu4NOH to yield (η5-C5R5)(PPh3)2M{C=C(R1)CHR2} 3 (cyclopropenyl complexes), which are observed during the cyclization process. However, only 3a (M = Os, R1 = Ph, R2 = CN), 3aa~3ac (M = Ru, R1 = Me, R2 = CN, Ph, CH=CH2) and 3bb (M = Ru, R1 = n-Bu, R2 = Ph) are isolated and the rest further transform into 4 (furan) or 5 (lactone) depending on the various group on vinylydene ligand of 2. Among all furan complexes 4, only 4e, 4ah, 4ch, 4ai, 4aj, 4ak and 4ck could further yield the lactone complexes 5e, 5ah, 5ch, 5ai, 5aj, 5ak and 5ck via sigmatropic rearrangements, respectively. The rate of rearrangement was affected by R1. The stability of the 3 in CHCl3 follows the trend for the substituents R1 of Ph ＞ Me ＞ n-Bu and for the substituents R2 of CN ＞ Ph ＞ CH=CH2. The bimetallic compounds of [M1]=C=C(R1)CH2C(CH2R2)=C=[M2] (11, M = Os or Ru) containing a methylene bridge are prepared, but only complexes 11da (M1 = Os, M2 = Ru, R1 = Ph, R2 = CN) and 11db (M1 = Os, M2 = Ru, R1 = Ph, R2 = CO2Et) proceed to produce bismetallic cyclic complexes 12 and 13, respectively after deprotonation. Using cationic osmium allenylidene complexes 14 and 14' with Grignard reagents R'CH2MgX, the acetylide complexes (η5-C5R5)(PPh3)2Os-C≡CC(Ph)2CH2R' are obtained. When they are further protonated by HBF4 in diethyl ether, corresponding vinylidene complexes [(η5-C5R5)(PPh3)2Os=C=CHC(Ph)2CH2R']+ (15, 15') are afforded. Most of complexes 15 are stable even in refluxing acetonitrile. Interestingly, two novel transformations are observed at ca. 50oC, including 15a (R = H, R' = CH=CH2) to [(η5-C5H5)(PPh3)2Os=C=CHCH2C(Ph)2(CH=CH2)]+ (17) caused by intramolecular metathesis process, and 15b (R = H, R' = C(Me)=CH2) to the cyclic allene complex 18 involved a C-C bond formation giving a six-membered ring and a change of coordination to a η2-allene mode. These similar transformations are also observed in ruthenium system (20'a → 22'a, 20'b → 26') in diethyl ether under low temperature (-20oC). The rates of the two transformations are closely related to the metallic fragments and the substituents at Cγ. Replacing diethyl ether with MeOH, the reaction of 20'a and HBF4 affords an unsaturated cyclic carbene complex 23', which is fully characterized by single-crystal X-ray diffraction analysis. Unexpectedly, dissolving 22'a in MeOH also obtains the same product 23'. The reaction mechanism is elucidated by deuterium and 13C labeling experiments results and proposed to involve a skeletal rearrangement. For comparison, complex 22'a in iPrOH yields, besides 23', the corresponding alkoxycyclohexene 25c. Formation of 25c from 22'a also involves a skeletal rearrangement with reconstruction of the C=C bond. The proposed mechanism implicates a cyclobutylidene intermediate formed via either a regiospecific [2+2] cycloaddition of two double bonds in the ruthenium-vinylidene 22'a, or via a 5-endo cyclization of 22'a giving a nonclassical ion intermediate followed by a 1,2-alkyl shift. Two types of cationic osmium and ruthenium vinylidene complexes, [(η5-C5R5)(PPh3)2M=C=C(R1)CH2R2] and [(η5-C5R5)(PPh3)2M=C=CHC(Ph)2CH2R'], were reported. By changing different alkylation group (R2), the former vinylidene complexes have been yielded various cyclic complexes (cyclopropene, furan and lactone). The reactivity of the other type [(η5-C5R5)(PPh3)2M=C=CHC(Ph)2CH2R']+ is closely related to the R' group.