Double Insertion Of Alkynes Research Articles

Efficient Synthesis of Highly Fused Quinazolinone Derivatives via Multiple C−C Bond Formations and 1,4‐Palladium Migration

AbstractAn efficient palladium‐catalyzed annulation of 3‐arylquinazolinones with mono and double alkyne insertion was developed for the synthesis of fused quinazolinone derivatives in 43–80 % yields. A notable effect was observed in product yield, when bases/additives were modulated. The reaction mechanism is believed to proceed through C−X cleavage/alkyne insertion/1,4‐Pd migration and C−H annulation in a one‐pot manner.

Synthesis of Cyclopenta[c]quinolines by Palladium-Catalyzed Cyclization of 3-Bromoindoles with Internal Alkynes via Spirocyclic Cyclopentadiene Intermediates.

A novel method for the construction of a cyclopenta[c]quinoline ring via cyclization of 3-bromoindoles with internal alkynes in the presence of palladium is described. The formation of the cyclopenta[c]quinoline ring is proposed from a double [1,5] carbon sigmatropic rearrangement of the spirocyclic cyclopentadiene intermediate, which is generated in situ from the cyclization of 3-bromoindoles with internal alkynes involving a sequential double alkyne insertion into the carbon-palladium bond and dearomatization of indole. The present studies have developed a novel ring-expansion reaction of the pyrrole ring to pyridine via one carbon insertion into the C2-C3 bond of indoles and provided a simple and distinct route for the construction of tricyclic fused-quinoline derivatives that are not easy to access with conventional methods.

Highly Efficient Construction of Pentacyclic Carboline‐Containing Salts via a [Cp*RhCl2]2‐Catalyzed Tandem Reaction

AbstractA [Cp*RhCl2]2‐catalyzed tandem reaction of indolyl aldehydes, amines, and alkynes featuring the formation of two C−C bonds, two C−N bonds, and one C=N bond is described. This strategy involves double C−H activation and double insertion of alkynes, furnishing a series of pentacyclic carboline‐containing salts in good yields under mild conditions. It provides a good choice for rapidly constructing libraries of such pentacyclic carboline‐containing salts.

ChemInform Abstract: Double Insertion of Alkynes into Chromium-Carbon Bonds of β-Donor- Substituted Vinylcarbene Complexes of Chromium - a Simple Route to Cyclopenta(b)pyrans.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Palladium- and Nickel-Catalyzed Carbon−Carbon Bond Insertion Reactions with Alkylidenesilacyclopropanes

Palladium and nickel catalysts promoted highly selective carbon-carbon bond insertion reactions with di-tert-butyl-alkylidenesilacyclopropanes. Pd(PPh(3))(4) was demonstrated to be the optimal catalyst, allowing for a variety of carbon-carbon pi-bond insertion reactions. Depending on the nature of the carbon-carbon pi bond, the insertion reaction proceeded with either direct insertion into the carbon(sp(2))-silicon bond or with allylic transposition. Ring-substituted alkylidenesilacyclopropanes required a nickel catalyst to afford insertion products. Using Ni(cod)(2) as the carbon-carbon bond insertion catalyst, new double alkyne insertion products and alkene isomerization products were observed.

Chemoselective methoxycarbonylation of terminal alkynes catalyzed by Pd(ii)-TROPP complexes

The mono-phosphanes 5-(diphenyl)-phosphanyl-5H-dibenzo[a,d]cycloheptene (TROPP(Ph)) and 5-((2-methoxy)phenyl)-phosphanyl-5H-dibenzo[a,d]cycloheptene (TROPP((2-MeOPh))) have been employed to coordinate PdCl(2), yielding [PdCl(2)(TROPP(Ph))] (1a) and [PdCl(2)(TROPP((2-MeOPh)))] (1b), respectively. The corresponding tosylate (OTs) complexes [Pd(OTs)(2)(TROPP(Ph))] (2a) and [Pd(OTs)(2)(TROPP((2-MeOPh)))] (2b) have been successfully applied in the p-benzoquinone (BQ)-assisted methoxycarbonylation of terminal alkynes to give chemoselectively the corresponding alkynylcarboxylic acid methyl ester with high TOF (up to 980 h(-1)). Unlike 2a/b, the Pd(II)-(tosylate)-diphosphane complexes [Pd(OTs)(H(2)O)(dppp)](OTs) 2c (dppp = 1,3-bis-di(phenylphosphanyl)propane and [Pd(H(2)O)(2)(MeO-dppp)](OTs)(2) 2d (MeO-dppp = 1,3-bis(di(2-methoxyphenyl)phosphanyl)propane) preferentially catalyzed a double alkyne insertion. The "in situ" spectroscopic observation of the Pd-methoxycarbonyl compound [Pd(COOMe)(TROPP(Ph))](OTs) (3a) in conjunction with the evidence of the fast beta-hydride elimination reaction of TROPP-based Pd-catalysts in the dimerization reaction of ethene are indicative for a strongly electrophilic metal centre. The X-ray crystal structures of 1a x 0.5 C(2)H(4)Cl(2) and of the neutral and cationic Pd-alkyl complexes [Pd(Me)(Cl)(TROPP(Ph)) (7a x 0.5 CH(2)Cl(2)) and [Pd(CH(2)CH(2)COMe)(TROPP(Ph))](PF(6)) (10a x 0.5 C(6)H(6)), respectively, confirm unambiguously the bidentate coordination mode of TROPP-ligands to Pd(II), that persists even in the presence of CO pressure.

A Strategy for C−H Activation of Pyridines: Direct C-2 Selective Alkenylation of Pyridines by Nickel/Lewis Acid Catalysis

The C-2 selective alkenylation of pyridine derivatives is achieved with a catalyst consisting of nickel and Lewis acid. Use of diorganozinc compounds as the Lewis acid catalyst gives C-2 monoalkenylation products, whereas AlMe3 changes the reaction course to afford C-2 dienylated products, which are derived from double insertion of alkynes into the C(2)−H bond. The reaction demonstrates a broad substrate scope and proceeds with high chemo-, regio-, and stereoselectivities under mild conditions compared with previous examples of direct C−H functionalization of pyridines.

Reactions of bis[dichloro(pentamethylcyclopentadienyl)rhodium(III) and -iridium(III)] with aromatic phosphine bearing a methoxy group at an ortho-position: double insertion of 1-alkynes into a RhO bond

Reactions of [Cp*MCl 2] 2 ( 1a: M=Rh, 1b: M=Ir; Cp*=C 5Me 5) with 2-methoxyphenylphosphines at room temperature gave the corresponding 1η-P coordination complexes, [Cp*MCl 2(PPh 3− n R n )] ( 2: n=1; 4: n=2; 6b: n=3 for R=C 6H 4-2-MeO). Reaction of 1 with (2-methoxyphenyl)diphenylphosphine at reflux in diglyme underwent demethylation to afford Cp*MCl(MMMPP- P, O) ( 3) (M=Rh, Ir; MMMPP- P, O= PPh 2(C 6H 4-2- O)) with a ( P, O) chelating ligand. In the reaction with bis(2-methoxyphenyl)phenylphosphine, Cp*MCl(BMMPP- P, O) ( 5) (M=Rh, Ir; BMMPP- P, O= PPh(C 6H 4-2-MeO)(C 6H 4-2- O)) was generated at reflux in a mixture of diglyme and MeOH. Tris(2-methoxyphenyl)phosphine reacted with 1a at reflux in MeOH to give Cp*RhCl(TMMPP- P, O) ( 7a) (TMMPP- P, O= P(C 6H 4-2-MeO) 2(C 6H 4-2- O)), whereas the reaction with 1b at reflux in EtOH generated Cp*Ir(TMMPP- P, O, O′) ( 8b) (TMMPP- P, O, O′= P(C 6H 4-2-MeO)(C 6H 4-2- O) 2) with a ( P, O, O′) tridentate ligand. Crystal structural analyses of 3a, 5a and 8b were carried out. Complex 3a underwent a double insertion of alkyne into a RhO bond on treatment with phenylacetylene or p-tolylacetylene in the presence of KPF 6, giving [Cp*Rh{ PPh 2(C 6H 4- O-CRCHCH CR}](PF 6) ( 9a: R= p-MeC 6H 4; 9b: R=Ph) with a ( P, O, C) tridentate ligand, in which X-ray crystal analysis of 9a was performed.

Novel single or double insertion of alkynes into rhodium– and iridium–oxygen or –phosphorus atom bonds and transannular addition of 1-alkynes between the rhodium atom and the ipso-carbon atom of the phosphorus ligand

Reactions of Cp*MCl(MDMPP-P,O) (1a: M = Rh; 1b: M = Ir; MDMPP-P,O = PPh2(C6H3-2-MeO-6-O)) or Cp*MCl(BDMPP-P,O) (2a: M = Rh; 2b: M = Ir; BDMPP-P,O = PPh(C6H3-2,6-(MeO)2)(C6H3-2-(MeO)-6-O)) with 1-alkynes were carried out in the presence of KPF6. Complex 1a reacted with HCCR (R = Ph, p-tolyl) to give [Cp*Rh{PPh2(C6H3-2-(MeO)-6-(O-CRCHCHCR))}](PF6) 5 bearing the (P,O,C) tridentate ligand derived from a head-to-head dimerization of 1-alkynes, whereas reaction with nBuCCH gave a head-to-tail double insertion complex 6, however the reactiones of 1b in MeOH gave carbene complexes [Cp*Ir{PPh2(C6H3-2-(MeO)-6-O)(C(OMe)CH2R)}](PF6) 13 and a carbonyl complex [Cp*Ir(CO){PPh2(C6H3-2-(MeO)-6-O)}](PF6) 14. Rhodium complexes 1a and 2a afforded [Cp*Rh(CO){PPh2(C6H3-2-(MeO)-6-(OCHC(COOR)))}](PF6) 8 or [Cp*Rh(CO){PPh(C6H3-2,6-(MeO)2)(C6H3-2-(MeO)-6-(OCHC(COOR)))}](PF6) 11 on treatment with HCCCOOR (R = Me, Et). Reactions of 1a, 1b, 2a or 2b with ROOCCCCOOR (R = Me, Et) gave [Cp*MCl{PPh2(C6H3-2-(MeO)-6-(OC(COOR)C(COOR)))}] (9: M = Rh, 17: M = Ir) and [Cp*MCl{PPh(C6H3-2,6-(MeO)2)(C6H3-2-(MeO)-6-(OC(COOR)C(COOR)))}] (12: M = Rh, 18: M = Ir), respectively. Reactions of 1a or 1b with HCCC6H4-4-COOMe bearing an electron-withdrawing substituent gave the head-to-head double insertion products (5c: M = Rh; 16: M = Ir) and Cp*MCl2[PPh2{CHC(C6H3-4-COOMe)(C6H3-2-(MeO)-6-(OH))}] (7: R = Rh; 15: R = Ir), and resulted in a cis-insertion into the P–C bond of the phosphine ligand and a cleavage of the Rh–O bond. Reaction with 2a afforded 10a, derived from a transannular addition of 1-alkyne between the Rh atom and the ipso-carbon atom of the phosphine ligand. Reactions of 9 with CO or isocyanides (L) in the presence of KPF6 or Ag(CF3SO3) gave [Cp*Rh(L){PPh2(C6H3-2-(MeO)-6-(OC(COOR)C(COOR)))}]X (L = XylNC, MesNC, CO; X = PF6, CF3SO3). Structural data for some complexes obtained here are described. The reaction mechanism is discussed.

Nickel-Catalyzed Silaborative Dimerization of Alkynes

Double insertion of alkynes into the Si−B bond of (dimethylphenylsilyl)pinacolborane proceeded in the presence of nickel(0) catalysts to give cis,cis-1-silyl-4-boryl-1,3-butadiene derivatives in a regio- and stereoselective manner. Involvement of (silyl)(2-boryl-1-alkylvinyl)nickel(II) intermediates in the silaborative dimerization reaction was suggested by the regiochemical preference as well as on the basis of reactions of the corresponding germylborane with alkynes in the presence of Ni, Pd, and Pt catalysts.

Double Insertion of Alkynes into Chromium‐Carbon Bonds of β‐Donor‐Substituted Vinylcarbene Complexes of Chromium—A Simple Route to Cyclopenta[b]pyrans

Double Insertion of Alkynes into Chromium‐Carbon Bonds of β‐Donor‐Substituted Vinylcarbene Complexes of Chromium—A Simple Route to Cyclopenta[<i>b</i>]pyrans

Double (internal/external) alkyne insertion reactions of α-diazoketones

Acetylenic α-diazoketone 5, when treated with Rh 2(OAc) 4 and several different alkynes, gives alkyne insertion/cyclopropenation products. Subsequent catalytic ring opening reactions demonstrate a highly regioselective net double alkyne insertion process and a new dihydropentalenone synthesis.