Synthesis of 2-pyridones and iminoesters via Rh(III)-catalyzed oxidative coupling between acrylamides and alkynes

Catalytic oxidative coupling between acrylamides and alkynes was achieved using 0.5 mol % loading of [RhCp*Cl(2)](2) with Cu(OAc)(2) as an oxidant. 2-Pyridones, iminoesters, and substituted indoles could be obtained as a result of the electronic and steric effects of the substituents in the acrylamides.     

The regio- and stereoselective one-pot catalytic preparation of beta-selenyl acrylamides

Pd(PPh(3))(4) is found to catalytically assemble sulfenamides, terminal aliphatic alkynes, carbon monoxide, and diphenyl diselenides regio- and stereoselectively in a single-pot reaction to produce good yields of beta-selenyl acrylamides. [reaction: see text]     

Rhodium-catalyzed linear cross-trimerization of two different alkynes with an alkene and two different alkenes with an alkyne

Crossing paths with rhodium: A cationic Rh(I)/H(8)-BINAP complex has been found to catalyze the linear cross-trimerization of terminal alkynes, acetylenedicarboxylates, and acrylamides to give substituted trienes. The asymmetric linear cross-trimerization, giving substituted chiral dienes, has also been achieved by using monosubstituted alkenes and (R)-BINAP instead of terminal alkynes and H(8)-BINAP (see scheme; H(8)-BINAP = 2,2'-bis(diphenylphosphino)-5,5',6,6',7,7',8,8'-octahydro-1,1'-binaphthyl; BINAP = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl]).     

Palladium-catalyzed regiospecific aminocarbonylation of alkynes in the ionic liquid [bmim][Tf2N

[Structure: see text] Regiospecific construction of 2-substituted acrylamides was achieved by palladium-catalyzed aminocarbonylation of alkynes in the ionic liquid [bmim][Tf2N] without any acid additive under relatively mild conditions. The ionic liquid was used as the reaction medium and also acted as a promoter. Acrylamides were obtained in moderate to excellent yields, and an important feature is that the catalyst system can be recycled five times without loss of catalytic activity.     

Highly Chemo‐, Regio‐, and Enantioselective Rhodium‐Catalyzed Cross‐Cyclotrimerization of Two Different Alkynes with Alkenes

It has been established that a cationic rhodium(I)/(R)‐tol‐binap complex catalyzes the cross‐cyclotrimerization of silylacetylenes, di‐tert‐butyl acetylenedicarboxylates, and acrylamides with excellent chemo‐, regio‐, and enantioselectivities. Unsymmetrical alkynoates can also be employed in place of di‐tert‐butyl acetylenedicarboxylate for this process, but with reduced chemoselectivity.     

Rhodium-Catalyzed Atroposelective Access to Axially Chiral Olefins via C−H Bond Activation and Directing Group Migration

Axially chiral open-chain olefins represent an underexplored class of chiral platform. In this report, two classes of tetrasubstituted axially chiral acyclic olefins have been accessed in excellent enantioselectivity and regioselectivity via C?H activation of (hetero)arenes assisted by a migratable directing group en route to coupling with sterically hindered alkynes. The coupling of indoles bearing an N-aminocarbonyl directing group afforded C–N axially chiral acrylamides with the assistance of a racemic zinc carboxylate additive. DFT studies suggest a β-nitrogen elimination–reinsertion pathway for the directing group migration. Meanwhile, the employment of N-phenoxycarboxamide delivered C?C axially chiral enamides via migration of the oxidizing directing group. Experiments suggest that in both cases the (hetero)arene substrate adopts a well-defined orientation during the C?H activation, which in turn determines the disposition of the alkyne in migratory insertion. Synthetic applications of representative chiral olefins are demonstrated.     

Palladium-complex-catalyzed regioselective Markovnikov addition reaction and dehydrogenative double phosphinylation to terminal alkynes with diphenylphosphine oxide

Palladium-1,2-bis(diphenylphosphino)ethane complex catalyzes regioselective Markovnikov addition of diphenylphosphine oxide to terminal alkynes in propionitrile, while the use of triarylphopshines, di(o-tolyl)phenylphosphine in particular, as the ligand leads to dehydrogenative double addition forming 1,2-diphenylphosphinyl-1-alkenes as major products.     

Diastereo‐ and Enantioselective Synthesis of (E)‐δ‐Boryl‐Substituted anti‐Homoallylic Alcohols in Two Steps from Terminal Alkynes

We report the highly diastereo‐ and enantioselective preparation of (E)‐δ‐boryl‐substituted anti‐homoallylic alcohols in two steps from terminal alkynes. This method consists of a cobalt(II)‐catalyzed 1,1‐diboration reaction of terminal alkynes with B₂pin₂ and a palladium(I)‐mediated asymmetric allylation reaction of the resulting 1,1‐di(boryl)alk‐1‐enes with aldehydes in the presence of a chiral phosphoric acid. Propyne, which is produced as the byproduct during petroleum refining, could be used as the starting material to construct homoallylic alcohols that are otherwise difficult to synthesize with high stereocontrol.     

含胺基功能性单体的聚合研究——X.N-(N′-次甲基吗啉)取代丙烯酰胺的合成及其聚合

<正> 聚丙烯酰胺及其N-取代衍生物是一类医用水凝胶,据Ferruti等报道,含有叔胺基的丙烯酸衍生物的聚合物具有抑制路易斯肺癌扩散的作用,我们曾合成了芳香及脂肪叔胺基取代的丙烯酰胺,并对它们的聚合及其作为氧化还原引发体系组分进行了研究,这些叔胺基取代的丙烯酰胺的聚合物,经复钙法测试,证明具有较好的抗凝血性。     

Copper-catalyzed α-selective C-H trifluoromethylation of acrylamides with TMSCF3

A copper-catalyzed α-selective C-H trifluoromethylation of acrylamides with TMSCF₃ is described. A wide range of arenes and heteroarenes at the β-position of acrylamides are compatible with the reaction, affording the corresponding (E)-trifluoromethylated products in moderate to good yields. The reaction proceeded fast and can be completed within 30 min.     

Formation and utility of oxasilacyclopentenes derived from functionalized alkynes

Oxasilacyclopentenes were shown to be synthetically useful masked allylic alcohols constructed in high yields and regioselectivities from terminal and internal alkynes. Several functional groups were shown to be tolerated utilizing silver-catalyzed silacyclopropenation of alkynes. In situ insertion of various carbonyl compounds into silacyclopropenes afforded regioselective formation of oxasilacyclopentenes. Elaboration of the oxasilacyclopentenes displayed the synthetic utility of these substrates. Both diastereoselective hydrogenation and Diels-Alder reactions utilizing the vinylsilane functionality demonstrated the reactivity and synthetic utility of oxasilacyclopentenes.     

含胺基功能性单体的聚合研究——Ⅷ.N-丙烯酰-N’-甲基吡嗪的合成、聚合及其聚合物的抗凝血性

<正> N—丙烯酰-N′-甲基吡嗪(AMP),N-甲基丙烯酰-N′-甲基吡嗪(MAMP)是丙烯酰胺,甲基丙烯酰胺的脂肪叔胺基N-取代物。聚丙烯酰胺是众所周知的医用水凝胶,其N-取代物也是甚多报道的生物相容性材料。以脂肪叔胺基取代的丙烯酰胺,除可期望其聚合物用作医用水凝胶外,分子内所含的叔胺基可以作为氧化还原引发体系的组分来引     

A Versatile Room‐Temperature Route to Di‐ and Trisubstituted Allenes Using Flow‐Generated Diazo Compounds

A copper‐catalyzed coupling reaction between flow‐generated unstabilized diazo compounds and terminal alkynes provides di‐ and trisubstituted allenes. This extremely mild and rapid transformation is highly tolerant of several functional groups.     

Scope and Limitations of the s-Block Metal-Mediated Pudovik Reaction

The hydrophosphorylation of phenylacetylene with di(aryl)phosphane oxides Ar₂P(O)H (Pudovik reaction) yields E/Z-isomer mixtures of phenylethenyl-di(aryl)phosphane oxides ( 1 ). Alkali and alkaline-earth metal di(aryl)phosphinites have been studied as catalysts for this reaction with increasing activity for the heavier s-block metals. The Pudovik reaction can only be mediated for di(aryl)phosphane oxides whereas P-bound alkyl and alcoholate substituents impede the P−H addition across alkynes. The demanding mesityl group favors the single-hydrophosphorylated products 1-Ar whereas smaller aryl substituents lead to the double-hydrophosphorylated products 2-Ar . Polar solvents are beneficial for an effective addition. Increasing concentration of the reactants and the catalyst accelerates the Pudovik reaction. Whereas Mes₂P(O)H does not form the bis-phosphorylated product 2-Mes , activation of an ortho-methyl group and cyclization occurs yielding 2-benzyl-1-mesityl-5,7-dimethyl-2,3-dihydrophosphindole 1-oxide ( 3 ).     

Influence of the Structure of (Meth)acrylamides on Their Spontaneous Polymerization in Concentrated Aqueous Solutions

A study was made of spontaneous polymerization of (meth)acrylamides of different structures in concentrated aqueous acid solutions, in particular, as influenced by the monomer association.     

Recent Mechanistic and Synthetic Developments in the Chemistry of Transition‐Metal Vinylidene Complexes

Transition‐metal vinylidene complexes are intermediates in a number of synthetically important transformations of alkynes. Underpinning these applications is the ability of various electron‐rich transition‐metal complexes to effectively facilitate the conversion of alkynes into their vinylidene tautomers. Recent experimental and theoretical studies have provided considerable insight into the mechanisms by which this process occurs and they are detailed herein. In particular, it has been demonstrated that different substituents on both the metal and the alkyne may have profound effects on both the kinetic and thermodynamic profiles of the alkyne/vinylidene tautomerisation. An important finding is that internal alkynes may be employed to prepare disubstituted vinylidene complexes under easily accessible conditions. This discovery brings to light a new facet of the potential synthetic applications of transition metal vinylidene complexes.     

Selective liquid-phase semihydrogenation of functionalized acetylenes and propargylic alcohols with silica-supported bimetallic palladium-copper catalysts

Silica-supported, bimetallic palladium-copper catalysts were prepared in solution under mild conditions by reacting lithium di(4-tolyl)cuprate with palladium acetate in the presence of silica particles. Small bimetallic palladium-copper particles were deposited on the silica surface as confirmed with TEM-EDAX and EXAFS. The new material has been applied as catalyst in the liquid-phase semihydrogenation of mono- and disubstituted alkynes and showed high selectivity toward the cis-alkenes. The influence of addition of quinoline or potassium hydroxide to the semihydrogenation reaction mixture and the effects of exposure of the catalyst to air before use have been investigated.     

Efficient,Simple Preparation of 1,3‐Diamine Derivatives through Addition of Acrylamides with Secondary Amines

Abstract

Reaction of acrylamides with secondary amines results in the formation of β‐amino‐propionamide through the addition reaction of N–H bond of amines across the double bond of acrylamides in the good to excellent yield. The structure of 2‐methyl‐3‐(1‐piperidinyl)‐propionamide has been determined by X‐ray analysis.     

Radical addition to isonitriles: a route to polyfunctionalized alkenes through a novel three-component radical cascade reaction

The reaction of aromatic disulfides, alkynes, and isonitriles under photolytic conditions affords polyfunctionalized alkenes--beta-arylthio-substituted acrylamides or acrylonitriles--in fair yields through a novel three-component radical cascade reaction. The procedure entails addition of a sulfanyl radical to the alkyne followed by attack of the resulting vinyl radical to the isonitrile. A fast reaction, e.g., scavenging by a nitro derivative or beta-fragmentation, is necessary in order to trap the final imidoyl radical, since addition of vinyl radicals to isonitriles seems to be a reversible process. The stereochemistry of the reaction is discussed, particularly with respect to the stereochemical outcome of related hydrogen abstraction reactions by the same vinyl radicals. The lower or even inverted preference for either geometrical isomer observed in our cases with respect to that encountered in hydrogen abstraction reactions is explained in terms of transition-state interactions and/or isomerization of the final imidoyl radical. The latter possibility is supported by semiempirical calculations, which show that the spin distribution in the imidoyl radical can allow rotation of the adjacent carbon-carbon double bond prior to beta-fragmentation.     

Palladium(II)‐catalyzed catalytic aminocarbonylation and alkoxycarbonylation of terminal alkynes: regioselectivity controlled by the nucleophiles

The aminocarbonylation and alkoxycarbonylation reactions of terminal alkynes took place smoothly and efficiently using a catalyst system Pd(OAc)₂–dppb–p‐TsOH? CH₃CN? CO under relatively mild experimental conditions. The catalytic system was tested and optimized using two different nucleophiles: alcohols and amines. Phenylacetylene (1a) was considered as an alkyne along with diisobutylamine (2b₁) and methanol (2c₁) as nucleophiles. The results showed significant differences in the conversion of 1a and in the selectivity towards the gem or trans unsaturated esters or amides with these nucleophiles. The effects of the type of palladium catalysts, the type of ligands, the amount of dppb and the solvents were carefully studied. With diisobutylamine (2b₁), excellent regioselectivity towards the 2‐acrylamides (gem isomer, 3ab₁) was almost always observed, while trans‐α,β‐unsaturated esters 4ac₁ was the predominant product with methanol (2c₁) as a nucleophile. This remarkable sensitivity in the selectivity of the reaction indicates two different possible mechanistic pathways for these carbonylation reactions. Copyright © 2009 John Wiley & Sons, Ltd.