Showing papers on "Heck reaction published in 1994"
TL;DR: In this paper, the presence of water is determined for the efficiency of quaternary ammonium salt (QX) in palladium-catalysed vinylation of organic halides using an alkali metal carbonate as the base, whether QX is a chloride, a bromide or a hydrogensulfate.
179 citations
TL;DR: A pentacyclic compound was synthesized as an important intermediate of antitumor antibiotic dynemicins as discussed by the authors, using the Heck reaction using catalytic Pd reagent, and an unusual spiro ring compound was found to be produced via intramolecular conjugate addition.
109 citations
87 citations
TL;DR: In this paper, the important role of silver salts in the asymmetric Heck reaction is discussed, and the conversion of 6 to δ-coniceine (24 ) is also described.
68 citations
TL;DR: The palladium-catalyzed asymmetric arylation of 4,7-dihydro-1,3-dioxepin 1d has been shown to give 2d-h (up to 75% ee), which can be readily converted to γ-butyrolactone derivatives.
60 citations
TL;DR: The asymmetric synthesis of L-699,392, a leukotriene antagonist, is described in this paper. But the main framework of the molecule is formed via a Heck reaction.
Abstract: The asymmetric synthesis of L-699,392, a leukotriene antagonist, is reported. The main framework of the molecule is formed via a Heck reaction. The introduction of the asymmetric center was accomplished by the chiral reduction of prochiral ketone using B-chlorodiisopinocampheylborane. A very high asymmetric amplification was observed in which 95% ee product can be obtained from 70% optically pure a-pinene. A new reagent, which is prepared in situ from methylmagnesium chloride and lithiumhexamethyldisilazide, is used to convert the methyl ester to the methyl ketone in one step with essentially no impurities formed under the reaction conditions.
56 citations
44 citations
TL;DR: In this article, the palladium-catalyzed olefination of different anilines with ethylene was shown to proceed generally in good yields, and substituted styrenes were obtained highly selective in a direct tandem diazotization Heck reaction at room temperature under atmospheric pressure of ethylene without concomitant side reaction to stilbenes.
44 citations
TL;DR: In this article, a new synthetic route to (±)-N 2 -(Benzensulfonyl)-CPI (16), the protected A-unit containing a cyclopropylhexadienone moiety of the highly potent antitumor antibiotic CC-1065 (1), from 5-(benzyloxy)-2-bromophenylamine (3) is described.
Abstract: A new synthetic route to (±)-N 2 -(Benzensulfonyl)-CPI (16), the protected A-unit containing a cyclopropylhexadienone moiety of the highly potent antitumor antibiotic CC-1065 (1), from 5-(benzyloxy)-2-bromophenylamine (3) is described. The key steps are a zirconium- and a palladium initiated cyclization to give the two pyrrole moieties. Reaction of 4a with zirconocene (methyl) chloride leads after workup with I 2 to the 4-iodoindoline 7a, which was transformed into 12 and subsequently via Heck reaction into the pyrroloindoline 15
41 citations
TL;DR: In this article, the palladium(II)-catalysed carbon-carbon-coupling reaction (Heck reaction) between a variety of metalated β-monohalosubstituted porphyrins (2-bromotetraphenylporphyrin, 2bromo-3,7,8,12,13,17,18,18-heptaethylporphrin, and 3(8)monoiodo-deuteroporphyporphypin IX dimethyl ester) and a series of termin
40 citations
TL;DR: In this paper, 1,3,5,7-Tetrakis(4-iodophenyl)adamantane was reacted with 2-methyl-3-butyn-2-ol and phenylacetylene under Pd-catalyzed Heck coupling cnnditions to give the two corresponding tetraacetylene derivatives.
Abstract: 1,3,5,7-Tetrakis(4-iodophenyl)adamantane was reacted with 2-methyl-3-butyn-2-ol and phenylacetylene under Pd-catalyzed Heck coupling cnnditions to give the two corresponding tetraacetylene derivatives. Deprotection of the first gave the derivative with free terminal acetylenes. Thermal cure of both acetylene-containing monomers was monitored by FTIR. Both NMR and FTIR confirmed the presence of adamantane in the otherwise all-aromatic structures. TGA indicated that these highly crosslinked materials began to degrade at ca. 450 and 490°C, respectively, in air
TL;DR: In this paper, it was shown that allylic ether substitution is compatible with intramolecular Heck chemistry and suggests applications of this chemistry in the synthesis of highly oxidized cardenolides.
TL;DR: In this paper, the stereoselective palladium-catalysed synthesis of the heterocycles 13-15 with a (Z)-exocyclic allylsilane moiety is described.
Abstract: The stereoselective palladium-catalysed synthesis of the heterocycles 13-15 with a (Z)-exocyclic allylsilane moiety is described. Alkylation of the secondary amides 5a, 5b, 9a, and 9b and the phenol 11 containing an iodoaryl moiety with the propargyl iodide 6 leads to the propargylsilanes 7a, 7b, 10a, 10b, and 12, which are allowed to react with a catalyst system of Pd(OAc)2/PPh3/NPr4Br and sodium formate as a hydride source. The (Z) configuration of the cyclisation products is confirmed by NOESY spectra and a single-crystal X-ray structure of 13b.
TL;DR: In this paper, two CC bonds are formed by nucleophilic addition of stabilized carbanions to the π-allylpalladium intermediate regioselectively produced by the Heck reaction of a vinyl bromide and an unactivated olefin.
TL;DR: Asymmetric Heck-type reaction of 1-cyclohexenylphenyliodonium salt with 2, 3-dihydrofuran was investigated for the first time in this paper.
Abstract: Asymmetric Heck-type reaction of 1-cyclohexenylphenyliodonium salt with 2, 3-dihydrofuran was investigated for the first time. The optically active (up to 78% ee) coupling product was obtained in low to moderate yield. The potential and associated problems of this asymmetric reaction are discussed.
TL;DR: The asymmetric Heck reaction has been successfully applied to catalytic asymmetric syntheses of many bioactive molecules such as vernolepin, γ-butyrolactone derivatives, eptazocine, a halenaquinol skeleton and lentiginosine as discussed by the authors.
Abstract: The asymmetric Heck reaction, which we achieved for the first time several years ago, has been successfully applied to catalytic asymmetric syntheses of many bioactive molecules such as vernolepin, γ-butyrolactone derivatives, eptazocine, a halenaquinol skeleton and lentiginosine.
TL;DR: Heck vinylation of tertiary allylic alcohols with iodo-acetal Ic, followed by an acid catalysed acetal hydrolysis-dehydration reaction, furnished isoprenoid aldehydes regioselectively in high yields as mentioned in this paper.
TL;DR: In this article, a previously described palladium-catalyzed tandem cyclisation leading to linear triquinanes has been generalized by disfavoring the competing Heck reaction, and two structural factors (nature of the nucleophile and of the vinylic halogen) play an important role in this generalization.
TL;DR: In this paper, the first crystal structure of a bis(ferrocenylvinyl)benzene chromophore was reported and up to three ferrocene units were introduced in one step by the multi-fold reaction of 1,2-dibromo- (4) or 1,3,5-tribromobenzene (6) with 1.
Abstract: (Ferrocenylvinyl)arenes 3, 5, and 7 are obtained from vinylferrocene (1) and substituted aromatic and heteroaromatic halides by palladium-catalyzed Heck-type reactions. Up to three ferrocene units are introduced in one step by the multi-fold reaction of 1,2-dibromo- (4) or 1,3,5-tribromobenzene (6) with 1. The first crystal structure of a bis(ferrocenylvinyl)benzene chromophore (5) is reported.
TL;DR: An efficient method for construction of the 23-arylbrassinosteroidal side-chain is described via Heck coupling and asymmetric osmylation as key steps.
Abstract: An efficient method for construction of the 23-arylbrassinosteroidal side-chain is described via Heck coupling and asymmetric osmylation as key steps. Several new (22R, 23R)-23- arylbrassinosteroids were synthesized. The overall yields of 23-phenylbrassinosteroid 18 and the new compound 13a from 22-olefin 7 were 10%(seven steps) and 37%(five steps), respectively.
TL;DR: In this article, the intramolecular olefin insertion to form mixtures of cis/trans-2-vinylcyclopentylacetyl- and cis-trans-cyclohexyl-acetylpalladium intermediates, which undergo further the 5-exo Heck reaction to give bicyclo-[3.3.0] and [4.3] skeletons, respectively, except for one case affording trans-2.
TL;DR: In this paper, an expedient synthesis of methyl 3-benzofuranylacetate was developed by employing the Heck reaction between 2-iodophenol and 2,5-dihydro-2-5-dimethoxyfuran as a key step.
Abstract: An expedient synthesis of methyl 3-benzofuranylacetate has been developed by employing the Heck reaction between 2-iodophenol and 2,5-dihydro-2,5-dimethoxyfuran as a key step
TL;DR: In this article, the Heck-type vinylation of various allylic alcohols with 2, followed by an acidic dehydration, delivers symmetrical carotenoids in good yields.
TL;DR: The increasing use of vinyl and aryl trifluoromethanesulfonates (triflates) is due to their facile preparation from carbonyl compounds and phenols.
Abstract: The increasing use of vinyl and aryl trifluoromethanesulfonates (triflates) is due to their facile preparation from carbonyl compounds and phenols. They undergo cross-coupling reactions with organo-metallics as the corresponding organic halides or addition reactions to alkenes and alkynes. Especially in the Heck reaction triflates proved to be superior to halides with respect to regio- and diastereoselectivity. Palladium-catalyzed carbon monoxide insertion of triflates leading to the corresponding esters or amides has found widespread application in natural product synthesis. Various deoxygenation procedures for ketones or phenols are based on the ease of removal of the trifluoromethanesulfoxy group
TL;DR: In this paper, the essential structural prerequisites of the catalyst to control metal-catalysed polycondensations are presented. But, unlike chain reactions with constant valence of the metal, step polymerization with changing valence is not a constant chain reaction.
Abstract: While metal-catalysed polymerizations are chain reactions with constant valence of the metal, metal-catalysed polycondensations are step polymerizations with changing valence of the metal. Taking as examples the Pd-catalysed vinyl polymerization of norbornene, the alternating copolymerization of ethylene and carbon monoxide, and the Heck reaction, the essential structural prerequisites of the catalyst to control those reactions are presented. Metal-catalysed polycondensations may occur as one- or two-electron processes. The oxidative polymerization of 2,6-dimethylphenol, and the Ni-catalysed polyphenylene synthesis are discussed