Cobalt-catalyzed Heck-type reaction of alkyl halides with styrenes

A cobalt complex, CoCl2[1,6-bis(diphenylphosphino)hexane], catalyzes an alkylation reaction of styrenes in the presence of Me3SiCH2MgCl in ether to yield beta-alkylstyrenes. A variety of alkyl halides including alkyl chlorides can be employed as an alkyl source. A radical mechanism is strongly suggested for this alkylation reaction.     

Cobalt-catalyzed sequential cyclization/cross-coupling reactions of 6-halo-1-hexene derivatives with Grignard reagents and their application to the synthesis of 1,3-diols

Cobalt/N-heterocyclic carbene system or cobalt/diamine combination effectively catalyzes sequential cyclization/cross-coupling reactions of 6-halo-1-hexene derivatives with trialkylsilylmethyl, 1-alkynyl, and aryl Grignard reagents. The sequential cyclization/cross-coupling reactions are applied to the synthesis of 1,3-diols starting from siloxy-tethered 6-halo-1-hexene derivatives.     

N-heterocyclic carbene ligands in cobalt-catalyzed sequential cyclization/cross-coupling reactions of 6-halo-1-hexene derivatives with Grignard reagents

[reaction: see text] N-Heterocyclic carbene/cobalt systems effectively catalyze sequential cyclization/cross-coupling reactions of 6-halo-1-hexene derivatives with trialkylsilylmethyl and 1-alkynyl Grignard reagents, which phosphine and amine ligands did not promote.     

New Heck-type reaction applied to the synthesis of protoporphyrin-IX derivatives

[reaction: se text] A new Heck-type reaction under catalysis by Pd for obtaining polysubstituted arylvinylydene derivatives of porphyrin systems is reported. The coupling between the Zn(II)-protoporphyrin-IX dimethylester Zn-2 and several bromo-aryl and iodo-aryl compounds in the presence of a new Pd catalyst has been studied. This coupling reaction, although providing moderate regioselectivity, gives quantitative conversion.     

Synthesis of 2,2-dimethyl-1-carbapenam derivatives via an intramolecular michael-type reaction

The synthesis of 2,2-dimethyl-1-carbapenam derivatives via an intramolecular Michael-type condensation reaction is described.     

Heck-type reaction of aryldiazonium silica sulfates

Abstract  

Aryldiazonium silica sulfates were employed as new and efficient reagents for Heck-type arylation reactions with styrene and methyl acrylate. The reactions were carried out in an organic solvent, in the presence of Pd(OAc)₂ as precatalyst without use of base and free ligand. The trans isomers of desired products, methyl cinnamates and stilbenes, were obtained with full conversion. Use of a catalytic amount of Pd(OAc)₂ produced the corresponding products in short reaction times and excellent yields.     

Synthesis of latonduine derivatives via intramolecular Heck reaction

The synthesis of indole ring-fused benzazepinone series as latonduine derivatives has been developed via an intramolecular Heck reaction. The scope has been enlarged not only to indole moiety but also to pyrrolo and benzo[b]thiophene nuclei. Several derivatives prepared have been evaluated in vitro for their antiproliferative activities on breast cancer cell lines. Some of them showed promising cytotoxic activities.     

Photochemical intramolecular nitrene insertion of 6-azidouridine derivatives

A highly efficient intramolecular nitrene insertion was observed upon irradiation of 6-azidouridine derivatives. The N⁶,2′-cyclo structure of the product was determined unequivocally by X-ray crystallography.     

Dehalogenation of 1-methyl-5-halo-4-substituted-pyridazin-6-ones

In order to confirm the regiochemistry for the functionalization of 1-(1,1-dibromo-2-oxopropyl)-4,5-dihalopyridazin-6-ones, the dehalogenation of 1-methyl-5-halo-4-substituted-pyridazin-6-ones using Pd/C and hydrogen was carried out. The results of the title reaction are reported.     

Reaction-phase-selective inter- and intramolecular photochemical reaction of 2-pyridone derivatives

Phase-selective photochemical reaction of 2-pyridone derivatives was examined. Irradiation of 1 in benzene mainly gave rearrangement products 2. However, intermolecular [4 + 4] photocycloaddition proceeded quantitatively in the solid state, affording photodimers 3. An effective pi-pi stacking and dipole-dipole interaction between two pyridone moieties might play important roles in an effective arrangement of 1 for photodimerization in their crystal structures. [reaction: see text]     

Oxidative cross-coupling of styrene and 1-hexene in acetoxylation reaction conditions

Reaction of heterogeneous-catalytic coupling of styrene and 1-hexene in glacial acetic acid was studied for the first time.     

4-Substituted 5-nitroisoquinolin-1-ones from intramolecular Pd-catalysed reaction of N-(2-alkenyl)-2-halo-3-nitrobenzamides

4-Methyl- and 4-benzyl-5-aminoisoquinolin-1-ones are close analogues of the water-soluble PARP-1 inhibitor 5-AIQ. Their synthesis was approached through Pd-catalysed cyclisations of N-(2-alkenyl)-2-iodo-3-nitrobenzamides. Reaction of N,N-diallyl-2-iodo-3-nitrobenzamide with Pd(PPh₃)₄ gave a mixture of 2-allyl-4-methyl-5-nitroisoquinolin-1-one and 2-allyl-4-methylene-5-nitro-3,4-dihydroisoquinolin-1-one. N-Benzhydryl-N-cinnamyl-2-iodo-3-nitrobenzamide similarly gave 2-benzhydryl-4-benzyl-5-nitroisoquinolin-1-one and 2-benzhydryl-4-benzylidene-5-nitro-3,4-dihydroisoquinolin-1-one. The isomeric products are not interconvertible. A deuterium-labelling study indicated that the isomers were formed by different pathways: a π-allyl-Pd route and the classical Heck route. The corresponding secondary amides N-allyl-2-iodo-3-nitrobenzamide and N-((substituted)-cinnamyl)-2-iodo-3-nitrobenzamide gave good yields of the required 4-methyl- and 4-((substituted)-benzyl)-5-nitroisoquinolin-1-ones, respectively, under optimised conditions (Pd(PPh₃)₄, Et₃N, Bu₄NCl, 150 °C, rapid heating). Hydrogenation of the nitro groups gave 4-methyl- and 4-benzyl-5-aminoisoquinolin-1-ones, which were potent inhibitors of PARP-1 activity.     

Synthesis of 6-halo-5-nitroquinoxalines

The 5-nitro derivatives of 6-haloquinoxalines have been efficiently synthesized by condensation of α-dicarbonyls with 4-bromo- or 4-chloro-3-nitro-1,2-benzenediamines. The novel diamines were readily obtained by reductive cleavage of 5-bromo- and 5-chloro-4-nitro-2,1,3-benzoselenadiazoles. As demonstrated by the synthesis of an imidazo-, a selenadiazolo- and a pyrazinoquinoxaline, the reactive halogen atom ortho to the nitro substituent renders the novel quinoxalines versatile intermediates to further heterocycles.     

Highly functionalized dihydrofuran derivatives: Synthesis by diastereoselective intramolecular Wittig reaction

3a,8a‐Dihydroxy‐1,3,3a,8a‐tetrahydro‐ indeno[1,2‐d]imidazole‐2,8‐dione 3 reacts with dialkyl acetylenedicarboxylates in the presence of triphenylphosphine to produce some novel interesting dihydrofuran derivatives diastereoselectively. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:277–279, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20202     

Photochemistry of 6-halo- and 5,6-dihalouracils. A simple synthesis of fluorescent uracil derivatives

6-Iodo- and 5,6-dihalouracil derivatives undergo remarkably efficient photocoupling reactions leading to strongly fluorescent heterocycles in the presence of suitable radical acceptors.     

A convenient synthesis of 7-halo-1-indanones and 8-halo-1-tetralones

A regioselective oxidation of N-indan-4-yl-acetamide or N-(5,6,7,8-tetrahydronaphthalen-1-yl)acetamide with potassium permanganate followed by acidic hydrolysis gave 7-aminoindan-1-one or 8-aminotetral-1-one in good yield. The amino ketones were converted to the corresponding 7-haloindanone or the 8-halotetralone. Another method to prepare 7-haloindan-1-ones was completed by a cyclization of 3-chloro-1-(2-halophenyl)propan-1-one under Friedel-Crafts conditions to produce the product in gram quantity.     

Palladium-catalyzed Heck-type reaction of 2-chloro acetamides with olefins

Conditions have been developed for the palladium-catalyzed Heck-type reaction of 2-chloro acetamides with several olefins. The regiochemistry of the products obtained speaks in favor of an involvement of palladium enolates in this reaction.