Palladium-catalyzed Intramolecular Heck Reaction Research Articles

Nickel-Catalyzed Enantioselective C(sp 3 )–H Arylation of Ketones with Aryl Ethers via Selective C Ar –O Cleavage to Construct All-Carbon Quaternary Stereocenters

Nickel-Catalyzed Enantioselective C(sp ³ )–H Arylation of Ketones with Aryl Ethers via Selective C _Ar –O Cleavage to Construct All-Carbon Quaternary Stereocenters

Construction of Indoline/Indolenine Ring Systems by a Palladium-Catalyzed Intramolecular Dearomative Heck Reaction and the Subsequent Aza-semipinacol Rearrangement.

The palladium-catalyzed intramolecular dearomative Heck reaction of 2,3-disubstituted indoles serves as an access to spiro-indoline products. Herein, we report an efficient construction of indoline/indolenine core stuctures via a dearomative Heck reaction of simple 2,3-disubstituted indoles with all-carbon tethers and the subsequent aza-semipinacol rearrangement. The Heck reaction features a high C2-selectivity, and the stereospecific aryl/alkyl migration selectivity has been investigated by DFT calculations. Using this method, we accomplished the formal total synthesis of akuammiline alkaloids vincorine.

A palladium-catalyzed intramolecular Heck/Hydrogenation approach towards the synthesis of praziquantel

Starting from 3-methoxy N-acylpyrazinium salts, a new approach towards the synthesis of the antischistosomal drug praziquantel (PZQ) has been developed. Utilization of a palladium-catalyzed intramolecular Heck reaction to form dehydro-PZQ followed by a Hydrogenation step, in a stepwise or one-pot manner, allowed for the gram scale synthesis of PZQ in 4 or 5 steps and in good overall yields. This methodology proved to be well suited for generating the pyrazino[1,2-a] isoindole and pyrazino[1,2-a] benzazepine analogues of PZQ.

ChemInform Abstract: Pd‐Catalyzed Intramolecular Heck Reaction, C(sp2)—H Activation, 1,4‐Pd Migration, and Aminopalladation: Chemoselective Synthesis of Dihydroindeno[1,2,3‐kl]acridines and 3‐Arylindoles.

Palladium-catalyzed intramolecular Heck reaction and aminopalladation of N-(2-(1-phenylvinyl)phenyl)aniline for the efficient synthesis of dihydroindeno[1,2,3-kl]acridines and 3-arylindoles via tuning of the phosphine ligands and solvents under two optimized conditions are reported. The reaction follows a 1,4-Pd migration, aminopalladation, C(sp2)–H activation, as well as five- and six-membered-ring fusion to form different products. The dihydroindeno[1,2,3-kl]acridine derivatives showed higher triplet energy (ET) levels than common blue phosphorescent dopant and may serve as good host candidates for blue triplet emitters.

Intramolecular Imidoylative Heck Reaction: Synthesis of Cyclic Ketoimines from Functionalized Isocyanide.

Efficient access to five- to seven-membered cyclic ketoimines, through palladium-catalyzed intramolecular imidoylative Heck reaction of alkene-containing isocyanides, has been developed. Consecutive isocyanide and alkene insertion into aryl or alkyl Pd(II) intermediates takes place in this process. No byproduct derived from monoinsertion or reversed sequence is detected.

Pd-Catalyzed Intramolecular Heck Reaction, C(sp2)–H Activation, 1,4-Pd Migration, and Aminopalladation: Chemoselective Synthesis of Dihydroindeno[1,2,3-kl]acridines and 3-Arylindoles

Palladium-catalyzed intramolecular Heck reaction and aminopalladation of N-(2-(1-phenylvinyl)phenyl)aniline for the efficient synthesis of dihydroindeno[1,2,3-kl]acridines and 3-arylindoles via tuning of the phosphine ligands and solvents under two optimized conditions are reported. The reaction follows a 1,4-Pd migration, aminopalladation, C(sp(2))-H activation, as well as five- and six-membered-ring fusion to form different products. The dihydroindeno[1,2,3-kl]acridine derivatives showed higher triplet energy (ET) levels than common blue phosphorescent dopant and may serve as good host candidates for blue triplet emitters.

Pd-catalyzed intramolecular C-N bond cleavage, 1,4-migration, sp3 C-H activation, and Heck reaction: four controllable diverse pathways depending on the judicious choice of the base and ligand.

Diverse and controllable pathways induced by palladium-catalyzed intramolecular Heck reaction of N-vinylacetamides for the synthesis of nitrogen-containing products in reasonable to high yields via tuning the phosphine ligands and bases are reported. Domino reactions including unique β-N-Pd elimination, 1,4-Pd migration, or direct acyl C-H bond functionalization were found to be involved forming different products, respectively. Given the ability of using the same starting material to generate diverse products via completely different chemoselective processes, these current methodologies offer straightforward access to valuable nitrogen-containing products under mild reaction conditions as well as inspire the discovery of novel reactions.

Synthesis of a furano abietane cyano enone—A new scaffold for biological exploration

A six step synthesis of furano abietane cyano enone 12 is described, in which the key step is a palladium-catalyzed intramolecular Heck reaction of bromo 3-phenoxyacrylate 17, prepared from enone phenol 13 in high yield.

One-pot, three-component synthesis of highly functionalized pyrimidone derivatives and access to indole fused pyrimidones via palladium-catalyzed intramolecular Heck reaction

A simple and facile approach to highly functionalized pyrimidone derivatives and indole fused pyrimidones has been developed. The synthesis of substituted pyrimidone derivatives in moderate to good yields involves [4+2] cycloaddition of 1,4-dipoles generated from α,β-unsarurated imines and dimethyl acetylenedicarboxylate (DMAD) with isocyanates as dipolarophiles. Furthermore, the pyrimidones resulted from 2-bromophenyl isocyanate could be transformed into various indole fused pyrimidones via intramolecular palladium-catalyzed Heck reaction under different conditions.

Novel synthesis of 4,4-difluoropyrido[4,3-b]indoles via intramolecular Heck reaction

Various difluoropyridoindoles were synthesized via a palladium-catalyzed intramolecular Heck reaction as a key step. Thus, ortho-bromoanilines and difluoropiperidinone were treated with (PPh3)2PdCl2 and base in pyridine to give the regioselective cyclized heterocycles in modest to satisfactory yields.

Ligand promoted and controlled palladium-catalyzed intramolecular Heck reaction of homoallyl alcohols: a facile synthesis of cyclopentaannulated quinolines

Bidentate phosphine ligands in palladium-catalyzed intramolecular Heck reactions of 2-chloroquinolin-3-yl-(1-homoallyl)alcohols are described to afford facile synthesis of 3-methylene-2,3-dihydro-1H-cyclopenta[b]quinolines in improved yields. We further observed using bulky aromatic phosphine ligand in Pd-catalyzed intermolecular Heck coupling reaction at olefinic centers with iodobenzene also favored exclusively Heck products in excellent yield.

Synthesis of Coumarin- and Quinolone-Annulated Benzazocinone Frameworks by a Palladium-Catalyzed Intramolecular Heck Reaction

A synthetic strategy based on the sequential application of an aromatic aza-Claisen rearrangement and an intramolecular Heck reaction as the key steps has been developed for the synthesis of various new coumarin- and quinolone-annulated benzazocinone derivatives in 60–70% yields.

Efficient Construction of Fused Indolines with a 2-Quaternary Center via an Intramolecular Heck Reaction with a Low Catalyst Loading

An efficient construction of fused indolines with a 2-quaternary center through a palladium-catalyzed intramolecular Heck reaction of N-(2(2-halobenzoxyl)-2,3-disubstituted indoles is disclosed. This protocol provided a straightforward access to diverse fused indolines with good functional group tolerance.

Ligand-free palladium-catalyzed intramolecular Heck reaction of secondary benzylic bromides

A facile ligand-free palladium-catalyzed intramolecular Heck reaction of β-hydrogen-containing secondary benzylic bromides was developed, which affords pyrroline derivatives with good regioselectivities.

Synthesis of benzodiazocine-annulated heterocycles by the implementation of Pd-catalyzed intramolecular Heck reaction

Abstract Synthesis of hitherto unreported benzodiazocine-annulated heterocycles by the implementation of palladium-catalyzed intramolecular Heck reaction has been achieved in excellent yields.

Concise Synthesis of Pyrimido-azocine Derivatives via Aza-Claisen Rearrangement and Intramolecular Heck Reaction

An expedient approach involving BF 3 ·OEt 2 -catalyzed aza-Claisen rearrangement and palladium-catalyzed intramolecular Heck reaction for the synthesis of pyrimidine-fused azocine derivatives is described. The mechanistic interpretation of the plausible mode of cyclization is also described.

Synthesis of Oxathiocine Derivatives by Palladium-Catalyzed Intramolecular Heck Reaction

A novel approach towards the synthesis of hitherto unreported oxathiocine derivatives has been described by utilizing palladium-catalyzed intramolecular Heck reaction starting from deactivated allylic compounds. Keywords: Heck reaction, sulfur heterocycles, 2-bromobenzene sulfonyl chloride, palladium catalyst, oxathiocine, 8-exo-trig

Novel Synthesis of Medium-Sized Heterocycles by Palladium-Catalyzed Intramolecular Heck Reaction via 9-endo-trig Mode of Cyclization

An efficient and high yielding method for the synthesis of nine-membered heterocyclic skeletons has been developed by palladium-catalyzed intramolecular Heck reaction via an unusual 9-endo-trig mode of cyclization.

Facile synthesis of benzo[4,5]furo[3,2- c]pyridines via palladium-catalyzed intramolecular Heck reaction

The heating of 4-chloropyridine with 2-bromophenol in either neat or DME as solvent gives rise to 2-bromophenoxy pyridines, which were treated with Pd(OAc) 2 and various ligands to afford functionalized benzo[4,5]furo[3,2- c]pyridines.

Synthesis of 3-Benzyloxy-6-methyl-7-methoxyphenanthrene-9-carboxaldehyde with Utilize Intramolecular Heck Reaction as the Key Step

Abstract The substituted phenanthrene-9-carboxyaldehydes are very important intermediates for the syntheses of phenanthroindolizidine and phenanthroquinolizidine alkaloids. The novel title compound was prepared from the reaction of 5 steps starting from the condensation of 3-methoxyl-4-methyl-phenylacetic acid and 4-(benzyloxy)-2-iodo-benzaldehyde, followed by esterification, cyclization, reduction, and oxidation. A new method for the preparation of phenanthrene ring via palladium-catalyzed intramolecular Heck reaction was described. The title compound was characterized by IR, 1 H NMR, 13 C NMR, elemental analysis, and MS.