Palladium-catalyzed mono-α-arylation of acetone with aryl halides and tosylates

We report the first example of selective Pd-catalyzed mono-α-arylation of acetone employing aryl chlorides, bromides, iodides, and tosylates. The use of appropriately designed P,N-ligands proved to be the key to controlling the reactivity and selectivity. The reaction affords good yields with substrates containing a range of functional groups at modest Pd loadings using Cs(2)CO(3) as the base and employing acetone as both a reagent and the solvent.     

Palladium-catalyzed Suzuki–Miyaura cross-coupling reaction of potassium 2-pyridyl trifluoroborate with aryl (heteroaryl) halides

Palladium-catalyzed Suzuki–Miyaura cross-coupling reaction of potassium pyridine-2-trifluoroborates and various aryl (heteroaryl) halides can generate the corresponding desired coupling products with moderate to good yields. It can be carried out under the conditions with ethanol as solvent, Pd(OAc)₂ and SPhos as catalyst system and Na₂CO₃ as a base.     

Palladium-catalyzed coupling of haloalkynes with allyl acetate: a regio- and stereoselective synthesis of (Z)-β-haloenol acetates

A Pd-catalyzed coupling of haloalkynes with allyl acetate has been reported, providing a convenient method for the stereoselective synthesis of (Z)-β-haloenol acetates in good yields. The synthetic utility of this method is demonstrated by the formation of functionalized enol acetates via the Suzuki-Miyaura or Sonogashira coupling of the resulting (Z)-β-haloenol acetate products.     

α-Metallated vinyl carbanionoids: III. Reactions of α-triorganostannylvinyllithiums with group IVB organometallic halides: Formation of α-trimethylplumbylvinyllithiums

Reactions of α-stannylvinyllithiums RR′CC(Li)SnMe₃ with halides Me₃MCl (M = Si, Ge, Pb) give the corresponding mixed bis(trimethylmetal)alkenes RR′CC(SnMe₃)₃. With two equivalents of methyllithium and trimethyllead chloride, RR′CC(SnMe₃)₂ can be converted to RR′CC(PbMe₃)₂. The latter, as well as RR′CC(SnMe₃)PbMe₃, undergoes transmetallation with methyllithium to give α-plumbylvinyllithiums RR′CC(Li)PbMe₃ which are more stable and apparently less basic than the corresponding α-stannyl anions.Multinuclear NMR data for the anionic species are presented and discussed.     

Pd-catalyzed cross-coupling of α-(acyloxy)-tri-n-butylstannanes with alkenyl, aryl, and heteroaryl electrophiles

Racemic and scalemic α-(acyloxy)-tri-n-butylstannanes undergo Pd-catalyzed cross-couplings with alkenyl/aryl/heteroaryl iodides, bromides, and triflates in moderate to good yields in THF at 45 °C. Simple aryl iodides and unprotected aza-arenes, two classes of electrophiles that typically react sluggishly, are also good substrates. Cross-couplings proceed with retention of configuration at the alkenyl and stannyl-substituted stereocenters.     

Synthesis of 2-(α-Hydroxyalkyl)-2-Oxazoline under Microwave Irradiation in Bluk

Oxazolineshavedemonstratedwideutilityinvariouschemicalfields,suchasinasymmetricsynthesis,asaco ordinationligand ,inmedicinalandmacromolecularsynthesis ,andasaprotectinggroupofcarboxylicacids[1～ 3] .Variousmethodshavebeenadvancedforthepreparationof 2 oxazolinesfromthereactionofβ aminoalcoholswithcarboxylicacids,esters,nitriles ,oraldehydessinceitsappearance[1～3] .Reagentssuchascomplexesorstrongacidsorbaseswereusuallyneededinthesevarioussyntheticmethods.Thereactiontakeslongtimetocompletion .…     

Reduction of Derivatives of α-Arylidene-α-(2-Thiazolyl)acetonitrile with Lithium Aluminum Hydride

The action of lithium aluminum hydride on derivatives of -arylidene--(2-thiazolyl)acetonitrile in absolute ether leads to reduction of the nitrile group without affecting the double bond conjugated with it. The reaction products are the corresponding substituted allylamines.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 221–224, February, 2005.     

Reactions of 2-(α-Haloalkyl)thiiranes with nucleophilic reagents: V. Reactions of 2-(α-Chloroalkyl)thiiranes with organolithium compounds

2-(α-Haloalkyl)thiiranes reacted with methyl-, butyl-, and phenyllithium to give the corresponding allyl sulfides. The reactions of diastereoisomeric erythro- and threo-2-(1-chloroethyl)thiiranes with phenyllithium were stereospecific, and they afforded (E)- and (Z)-1-phenylsulfanylbut-2-enes, respectively. 3-Chloromethyl-2,2-dimethylthiirane and phenyllithium gave rise to a mixture of 3-methyl-3-phenylsulfanylbut-1-ene and 3-methyl-1-phenylsulfanylbut-2-ene. The reactions of 2-chloromethylthiiranes with phenyllithium and methyllithium in the presence of a catalytic amount of copper(I) iodide (10 mol %) led to the formation of substituted thiiranes as the major products. Mechanisms of the observed transformations are discussed.     

Palladium-catalyzed phosphorus-carbon bond formation: cross-coupling reactions of alkyl phosphinates with aryl, heteroaryl, alkenyl, benzylic, and allylic halides and triflates

The direct formation of H-arylphosphinates and related compounds can be accomplished using palladium catalysis. This full paper examines the scope and some mechanistic aspects of this phosphorus-carbon bond forming reaction. The reactions of alkenyl and allylic halides are also described for the first time. This novel cross-coupling provides a convenient access to a variety of substituted H-phosphinates.     

Access to substituted trifluoromethyl ketones using the versatile synthetic intermediate (E)-1,1-dimethyl-2-(1,1,1-trifluoropropan-2-ylidene)hydrazine

The N,N-dimethylhydrazone of 1,1,1-trifluoroacetone, (E)-1,1-dimethyl-2-(1,1,1-trifluoropropan-2-ylidene)hydrazine, has been shown to undergo a diverse set of reactions following deprotonation with n-butyl-lithium; including alkylation, addition to ketones and aldehydes, as well as palladium-catalyzed cross-couplings with aryl bromides. Mild hydrolysis of the N,N-dimethylhydrazone products from these transformations affords the corresponding trifluoromethyl ketones in good to excellent yields.     

CuCl2/8-Hydroxyquinoline-catalyzed α-Arylation of Diethyl Malonate with Aryl Bromides

A general and efficient coupling of aryl bromides with diethyl malonate is presented. The reaction provided the α-arylated diethyl malonates in moderate to good yields with a low loading of CuCl₂(5%, molar fraction) and 8-hydroxyquinoline(5%, molar fraction). This method has good compatibility for a wide range of aryl bromides.     

Direct functionalization of the cyclometalated 2-(2′-pyridyl)phenyl ligand bound to iridium(III)

Treatment of [Ir(ppy)₂(μ-Cl)]₂ and [Ir(ppy)₂(dtbpy)][OTf] (ppy = 2-(2′-pyridyl)phenyl; dtbpy = 4,4′-di-tert-butyl-2,2′-bipyridine; OTf = triflate) with pyridinium tribromide in the presence of Fe powder led to isolation of [Ir(4-Br-ppy)(μ-Br)]₂ (1) and [Ir(4-Br-ppy)₂(dtbpy)][OTf] (2), respectively. Pd-catalyzed cross-coupling of 2 with RB(OH)₂ afforded [Ir(4-R-ppy)₂(dtbpy)][OTf] (R = 4′-FC₆H₄ (3)), 4′-PhC₆H₄ (4), 2′-thienyl (5), 4′-C₆H₄CH₂OH (6). Treatment of 4 with B₂(pin)₂ (pin = pinacolate) afforded [Ir{4-(pin)B-ppy}₂(dtbpy)][OTf] (7). The alkynyl complexes [Ir(4-PhCC-ppy)₂(dtbpy)][OTf] (8) and [Ir{4-Me₂(OH)CC-ppy}(4-Br-ppy)(dtbpy)][OTf] (9) were prepared by cross-coupling of 2 with PhCCSnMe₃ and Me₂C(OH)CCH, respectively. Ethynylation of [Ir(fppy)₂(dtbpy)][OTf] (fppy = 5-formyl-2-(2′-pyridyl)phenyl) with Ohira’s reagent MeCOC(N₂)P(O)(OEt)₂ afforded [Ir{5-HCC-ppy}₂(dtbpy)][OTf] (10). The solid-state structures of 2, 5, 7, and 10 have been determined.     

Highly regioselective Heck reactions of heteroaryl halides with electron-rich olefins in ionic liquid

Palladium-catalyzed Heck reactions of the heteroaryl halides, halopyridines, bromoquinoline and bromothiophenes, with the electron-rich olefins vinyl ethers and allyl alcohol were shown to give essentially only the branched olefins in an imidazolium ionic liquid, whereas in molecular solvents a mixture of regioisomers was formed. The method obviates the need for aryl triflates and stoichiometric inorganic salt additives, providing an easy entry to functionalized heteroaromatics incorporating acetyl and 2-allyl alcohol functionalities.     

以乙腈为氰甲基源合成氰基化的偕二氟烯烃

报道了以乙腈为氰甲基源,LiHMDS为碱,在室温下通过氰甲基化α-（三氟甲基）芳基乙烯,合成了一系列氰基化的偕二氟烯烃.该方法具有反应条件相对温和、反应迅速、操作简单、官能团兼容性较好、收率较高等优点.     

A general synthesis of diversely substituted indazoles and hetero-aromatic derivatives from o-halo-(het)arylaldehydes or -phenones

A set of variously substituted indazoles and hetero-aromatic derivatives were synthesized from o-halo-(het)arylaldehydes using a palladium catalyzed amination followed by cyclization. Starting from phenones, this process was extended to give 3-substituted indazoles. Moreover, N-1-substituted-indazoles can be reached by this strategy using an optional selective N-1-alkylation step during the process. This methodology offers a general and easy route for the synthesis of regioselectively substituted indazoles.     

2-(Trimethylsilyl)ethanesulfonyl amide as a new ammonia equivalent for palladium-catalyzed amination of aryl halides

2-(Trimethylsilyl)ethanesulfonyl amide (SES-NH₂) is an ammonia equivalent for the palladium-catalyzed amination of aryl bromides and aryl chlorides. Using these amine derivatives, it has been observed that anilines and anilines with sensitive functional groups can be readily prepared.     

甲基酮的二氟同系化-卤化反应:一锅法合成β-卤代-α,α-二氟代酮

以（溴二氟甲基）三甲基硅烷（TMSCF₂Br）为二氟卡宾源,利用其兼具TMS转移特性及自活化特性,仅在催化量的n-Bu₄NBr的催化启动下,直接完成甲基酮的烯醇化-二氟环丙烷化反应以及与卤正离子的开环卤化反应,并使用卤负离子作为卤源,采用其原位氧化形成卤正离子的方法实现了偕二氟环丙烷硅醚的开环-卤化,合成了β-卤代-α,α-二氟代酮类物质.     

Direct synthesis of α-hydroxyketone phosphates from terminal alkynes and H-phosphine oxides in the presence of PhI(OAc)_2 and H_2O

A simple and highly efficient one-pot method for the construction of α-hydroxyketone phosphates from terminal alkynes and H-phosphine oxides has been developed in the presence of PhI(OAc)_2 and H_2O.The present protocol provides an attractive approach to α-hydroxyketone phosphates in good to high yields,with the advantages of operation simplicity,the use of commercially available materials,broad substrate scope,high atom efficiency and good tolerance to scale-up synthesis.