Isolation and X-ray characterization of palladium–N complexes in the guanylation of aromatic amines. Mechanistic implications

• Abdessamad Grirrane,
• Hermenegildo Garcia and
• Eleuterio Álvarez

Beilstein J. Org. Chem. 2013, 9, 1455–1462, doi:10.3762/bjoc.9.165

• with the still not isolated aniline–carbodiimide palladium complex 6, in the mechanism of the guanylation of anilines. Our study opens the way to apply a similar methodology to study the reaction mechanism of other catalytic reactions. (Top) ORTEP view of the centrosymmetric molecule 4a. (Bottom

Homolytic substitution at phosphorus for C–P bond formation in organic synthesis

• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 1269–1277, doi:10.3762/bjoc.9.143

• of perfluorodecyldiphenylphosphine coordinate to palladium dichloride to form a catalytically active palladium complex that is useful for a fluorous/organic biphasic system. Cummins devised radical phosphination of bromobenzene or bromocyclohexane with white phosphorus by means of a trivalent

N-Heterocyclic carbene–palladium(II)-1-methylimidazole complex catalyzed Mizoroki–Heck reaction of aryl chlorides with styrenes

• Ting-Ting Gao,
• Ai-Ping Jin and
• Li-Xiong Shao

Beilstein J. Org. Chem. 2012, 8, 1916–1919, doi:10.3762/bjoc.8.222

• ) as the ionic liquid. Keywords: aryl chloride; Mizoroki–Heck reaction; N-heterocyclic carbene; palladium complex; synthetic method; Introduction The palladium-catalyzed reaction between organic halides and alkenes, the Mizoroki–Heck reaction, is one of the most versatile methods for the formation of

Palladium-catalyzed dual C–H or N–H functionalization of unfunctionalized indole derivatives with alkenes and arenes

• Gianluigi Broggini,
• Egle M. Beccalli,
• Andrea Fasana and
• Silvia Gazzola

Beilstein J. Org. Chem. 2012, 8, 1730–1746, doi:10.3762/bjoc.8.198

• easily removed from IV by the anion formed from the initial palladium salt with generation of the 3-indolyl-palladium complex V, which evolves a Heck-type reaction to give the 3-alkenylindoles 1. Conversely, the deprotonation of the C-3 position is difficult in acidic medium, favoring the transfer of

• thought to explain the outcome of the reaction. Firstly, Pd(II) catalyst promotes the formation of the π-allyl-palladium complex VIII, which can evolve by coordination of the N-1 or C-3 positions of the indole nucleus giving the palladium complexes IX and X, respectively. The latter quickly converts into

• the σ-alkyl-palladium intermediate XI by a Claisen-type rearrangement that involves the metal species. A mechanism through the typical π-olefin-palladium complex as the precursor of the σ-alkyl-palladium complex XI cannot, however, be ruled out. In every case, a Pd(0) species was released from XI and

Extending the utility of [Pd(NHC)(cinnamyl)Cl] precatalysts: Direct arylation of heterocycles

• Anthony R. Martin,
• Anthony Chartoire,
• Alexandra M. Z. Slawin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2012, 8, 1637–1643, doi:10.3762/bjoc.8.187

• preparation of the palladium complex 4. Following the strategy recently reported by Markó [23], we were successful in the synthesis of the IPr*Tol·HCl imidazolium salt 5 in a 53% overall yield (see Supporting Information File 1). Subsequently, 5 was treated with KOt-Bu in dry THF to generate the corresponding

Recent advances in direct C–H arylation: Methodology, selectivity and mechanism in oxazole series

• Cécile Verrier,
• Pierrik Lassalas,
• Laure Théveau,
• Guy Quéguiner,
• François Trécourt,
• Francis Marsais and
• Christophe Hoarau

Beilstein J. Org. Chem. 2011, 7, 1584–1601, doi:10.3762/bjoc.7.187

• by the isonitrile function, leading to the ring-close aryloxazol-2-yl palladium complex delivering products after a final reductive elimination step (Scheme 3). Catalytic direct (hetero)arylation of (benz)oxazoles Palladium- and/or copper-catalyzed direct (hetero)arylation with halides: Synthetic

• direct arylation of benzoxazole and the aza-analogues using a strong base [57][58]. Thus, the arylpalladium complex is engaged in a Passerini-type reaction with the 2-metallated benzoxazole ring-open tautomer, leading directly to the ring-close benzoxazol-2-yl(aryl)palladium complex, and finally to the 2

• ). Thus, C2 selectivity was only attained by using the highly steric P(t-Bu)3/PivOH pair, whereas the less electron-donating tri(alkyl)arylphosphines as well as bidentate ligands were prompted to form an aryl-palladium complex possessing a highly electrophilic character, leading to C5-arylation. Catalytic

Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• still-operative palladium complex. To do so, a terminal alkyne and caesium carbonate were added to the reaction mixture containing the newly formed 4-iodopyrrole, and the reaction temperature was increased to 70 °C (Scheme 17) [17]. Grigg and coworkers reported a three-component cascade process for the

• Pd-catalyzed cross-coupling approach starting from 1-chloro-2-iodobenzenes, phenylacetylene and a variety of primary amines [28][29]. The sequential three-component reaction was performed with the aid of an N-heterocyclic carbene-palladium complex generated in situ, derived from imidazolium salt 50

• , oxidative addition of the aryl halide to the Pd(0) catalyst generates an organopalladium reagent, which activates the alkyne moiety towards nucleophilic attack of the amino group. A reductive elimination generates the indole derivatives 59. In this one-pot three-component reaction, the same palladium

Amine-linked diglycosides: Synthesis facilitated by the enhanced reactivity of allylic electrophiles, and glycosidase inhibition assays

• Ian Cumpstey,
• Jens Frigell,
• Elias Pershagen,
• Tashfeen Akhtar,
• Elena Moreno-Clavijo,
• Inmaculada Robina,
• Dominic S. Alonzi and
• Terry D. Butters

Beilstein J. Org. Chem. 2011, 7, 1115–1123, doi:10.3762/bjoc.7.128

• -allyl palladium complex could explain the formation of 26. Finally, we report the results of assays of the unprotected diglycosides Man(N4–6)Glc 21 and Man(N4–6)Man 22, along with those we had synthesised earlier [6], viz., Alt(N2–6)Glc 28, Alt(N2–6)Man 29, Alt(N3–6)Glc 30, Alt(N3–6)Man 31, Glc(N6–6)Glc

Air-stable, recyclable, and time-efficient diphenylphosphinite cellulose-supported palladium nanoparticles as a catalyst for Suzuki–Miyaura reactions

• Qingwei Du and
• Yiqun Li

Beilstein J. Org. Chem. 2011, 7, 378–385, doi:10.3762/bjoc.7.48

• Qingwei Du Yiqun Li Department of Chemistry, Jinan University, 510632 Guangzhou, China 10.3762/bjoc.7.48 Abstract A diphenylphosphinite cellulose palladium complex (Cell–OPPh2–Pd0) was found to be a highly efficient heterogeneous catalyst for the Suzuki–Miyaura reaction. The products were

• and related reactions is also widely used [32][33][34]. Herein, we report the synthesis of a novel diphenylphosphinite cellulose palladium complex (Cell–OPPh2–Pd0) by a simple procedure from diphenylphosphinite funtionalized cellulose (Cell–OPPh2) and PdCl2 in ethanol solution [35][36][37][38][39][40

• ][41][42][43][44]. This class of supported palladium catalysts would solve the basic problems of homogeneous catalysts, i.e., the separation and recycling of the catalysts. This palladium complex catalyst also has the advantage of avoiding contamination of the products by residue ligand and metal

Palladium-catalyzed formation of oxazolidinones from biscarbamates: a mechanistic study

• Benan Kilbas and
• Metin Balci

Beilstein J. Org. Chem. 2011, 7, 246–253, doi:10.3762/bjoc.7.33

• product (Scheme 6). In the case of 8, 16 and 19, the leaving groups, carbamates, are in anti (referred to the cyclopropane ring) positions and, therefore, the palladium complex should approach the double bond in 8, 16, and 19 from the side of the three-membered ring to form a complex. However, the

• cyclopropyl hydrogens H-6 in 8 and 16 are located over the six-membered ring. These hydrogen atoms block the syn-face of the double bond and may hinder the approach of the palladium complex from the side of the cyclopropane ring. However, the products 9 and 17 were formed under the same reaction conditions in

• replaced with the cyano group as in 19. The reaction of 19 with the palladium complex was also unaffected or retarded; the product 20 was formed in a yield of 45%. In light of these results, we assume that complexation and ionization must be considered together. The removal of one of the enantiotopic

Suzuki–Miyaura cross-coupling reaction of 1-aryltriazenes with arylboronic acids catalyzed by a recyclable polymer-supported N-heterocyclic carbene–palladium complex catalyst

• Guangming Nan,
• Fang Ren and
• Meiming Luo

Beilstein J. Org. Chem. 2010, 6, No. 70, doi:10.3762/bjoc.6.70

• . Various aryltriazenes were investigated as electrophilic substrates at room temperature to give biaryls in good to excellent yields and showed good chemoselectivity over aryl halides in the reactions. Keywords: 1-aryltriazenes; N-heterocyclic carbene–palladium complex; polymer-supported catalyst

Regioselective alkynylation followed by Suzuki coupling of 2,4-dichloroquinoline: Synthesis of 2-alkynyl- 4-arylquinolines

• Ellanki A. Reddy,
• Aminul Islam,
• K. Mukkanti,
• Venkanna Bandameedi,
• Dipal R. Bhowmik and
• Manojit Pal

Beilstein J. Org. Chem. 2009, 5, No. 32, doi:10.3762/bjoc.5.32

• of 2,4-dichloroquinoline at C-2 position. The 2-alkynyl-4-chloroquinolines 3 thus formed then undergo Suzuki reaction in the next step. Oxidative addition of Pd0 generated in situ to compound 3 followed by trans-organometallation of the resultant aryl-palladium complex formed with arylboronic acids

Understanding the mechanism of Pd-catalyzed allylic substitution of the cyclic difluorinated carbonates

• Jun Xu,
• Xiao-Long Qiu and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2008, 4, No. 18, doi:10.3762/bjoc.4.18

• the monopalladium complex 11, which was too unstable to be isolated (Scheme 4). Neither did substitution of PPh3 by dppe deliver our desired complex 12 but gave instead the palladium complex 13, whose structure was confirmed by X-ray structure analysis. In our opinion, the reason we failed to isolate

• isolate the palladium complex 13 as the only product. In conclusion, we have investigated the reaction mechanism of Pd-catalyzed allylic substitution of cyclic gem-difluorinated intermediates in detail via the crystal structure and 13C NMR spectroscopy of the Pd-π-allyl complex. We found that the Pd

The oxanorbornene approach to 3-hydroxy, 3,4-dihydroxy and 3,4,5-trihydroxy derivatives of 2-aminocyclohexanecarboxylic acid

• Ishmael B. Masesane,
• Andrei S. Batsanov,
• Judith A. K. Howard,
• Raju Mondal and
• Patrick G. Steel

Beilstein J. Org. Chem. 2006, 2, No. 9, doi:10.1186/1860-5397-2-9

• , palladium mediated reactions of vinyl epoxides are known to proceed with allylic cleavage.[24] Subsequent addition of hydrogen to the intermediate π-allyl palladium complex would provide the desired 4-hydroxy-ACHC derivative. In agreement with this analysis, reaction of the epoxides with hydrogen in the