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Main observation and conclusion: Allenes and oxindoles are two classes of very important compounds for medicinal chemistry and organic chemistry. Thus, it is of high interest to combine an allene and an oxindole into one molecule. Herein, the first example of palladium‐catalyzed exclusive 2,3‐allenylation reaction of oxindoles with 2,3‐allenylic carbonates has been successfully developed. A rationale for the selectivity of 2,3‐allenylation over the expected 1,3‐alkadienylation has been proposed. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: The first example of Rh‐catalyzed kinetic resolution of 1,3‐disubstituted allene‐1,3‐dienes involving intramolecular [4+2]‐cycloaddition has been developed. Followed by C=C isomerization, the reaction finally afforded aza‐[4.3.0]bicyclic compounds with a very high enantio‐ and E‐selectivity. The mechanism has been unveiled by careful control experiments. The synthetic potentials of highly enantioenriched bicyclic products have also been demonstrated. [ABSTRACT FROM AUTHOR]

A comprehensive study on aerobic oxidation of benzylic alcohols to carboxylic acids with a catalytic amount each of Fe(NO3)3·9H3O, TEMPO, and KCl is conducted. Various synthetically useful functional groups are well tolerated in the reaction. Distinct electronic and steric effects are observed in the reaction: electron-withdrawing groups accelerate the reaction while electron-donating groups make the reaction slower, and ortho-substituted substrates react slower than meta-substituted substrates. Several large-scale reactions (100 mmol) are conducted using a slow air flow of 30 mL/min to demonstrate the practicality of this method in an academic laboratory. [ABSTRACT FROM AUTHOR]

A nickel-catalyzed three-component hydrocarboxylation of diynes with ZnEt2 and CO2 (1 atm) is disclosed. With this method, symmetric/nonsymmetric diynes could be reacted smoothly with very high stereo- and regioselectivity, affording conjugated 2,4-alkadienoic acids incorporated with five- or six-membered rings efficiently. A stepwise non-oxidative cyclometalation mechanism was proposed based on careful mechanistic studies. [ABSTRACT FROM AUTHOR]

This paper discusses the enrichment and depletion regularities for porphyry copper-molybdenum ore deposits in different regions and varied deposit genetic types in the same area, taking three porphyry copper-molybdenum ore deposits (i.e., the Chengmenshan in Jiangxi, Wunugetushan in Inner Mongolia, Baishantang in Gansu) and two copper deposits in Gansu Province (the Huitongshan skarn deposit and Gongpoquan composite deposit) as case studies. The results show that porphyry Cu-Mo deposits or skarn copper deposits include both enrichment of the ore-forming elements and associated elements, and depletion of some lithophile dispersed elements, rare earth elements (REE) and some major elements. And the depleted elements vary with deposits, having generality and their own features. On a deposit scale, the positive anomalies of enriched elements and negative anomalies of depleted elements follow in a sequence to comprise regular anomaly models of spatial structures. The exploration in the Tongchang deposit in Jiangxi and Huitongshan deposit in Gansu suggests that anomaly models play a key role in the identification of mineral occurrences and deposits compared to one single enriched element anomaly. And the anomaly models exert a critical effect on the optimization of prospecting targets and their potential evaluation. [ABSTRACT FROM AUTHOR]

A first practical Ni(0)-catalyzed highly stereoselective methyl-carboxylation of homopropargylic alcohols with ZnMe2and CO2for the efficient synthesis of α-alkylidene-γ-butyrolactones is described. The reaction may be applied to other alkynols. [ABSTRACT FROM AUTHOR]

Treatment of [PdI(Ph)(PPh 3)] 2with allenes CH 2CCHR (R = CMe 3, CO 2Et, P(O)(OEt) 2, and SO 2Ph) in dichloromethane at room temperature produces a mixture of cis and trans isomers of the π-allyl palladium complexes PdI(η 3-CH 2C(Ph)CHR)(PPh 3) in which the R group is anti to the Ph group. The disubstituted allenes MeCHCCHR (R = P(O)(OEt) 2and SO 2Ph) similarly react with [PdI(Ph)(PPh 3)] 2to give the π-allyl palladium complexes PdI(η 3-MeCHC(Ph)CHR)(PPh 3) in which the R group is anti and the Me group is syn to the Ph group. PdI(Ph)(dppe) alone was found to be unreactive toward allenes such as CH 2CCHSO 2Ph and MeCHCCHSO 2Ph at room temperature. In contrast, in the presence of TlPF 6, PdI(Ph)(dppe) readily reacts with allenes CH 2CCHR (R = CMe 3, CO 2Et, COPh, and SO 2Ph) and MeCHCCHSO 2Ph to give the π-allyl palladium complexes [Pd(η 3-CH 2C(Ph)CHR)(dppe)]PF 6and [Pd(η 3-MeCHC(Ph)CHR)(dppe)]PF 6, respectively. Although mechanistically possible, vinyl complexes were not observed as the insertion products in all cases. The substituents of allenes appear to have no effect on the reaction pathways, at least for the allenes used in this study. The insertion reactions involving PdI(Ph)(PR 3)(allene) have been studied by computational chemistry using the model complex PdI(Ph)(MeCHCCHSO 2H)(PH 3). [ABSTRACT FROM AUTHOR]

Efficient synthetic routes to construct multisubstituted benzo[1,2-b:5,4-b′]difurans and benzo[1,2-b:4,5- b′]difurans from bis(allyloxy)bis(alkynyl)benzenes or bis(alkynyl)dihydroxybenzenes and allylic halides utilizing palladium-catalyzed double annulations is reported. By further applying a double ring-closing metathesis reaction, pentacyclic compounds were also prepared. [ABSTRACT FROM AUTHOR]

Cyclometallation of two unsaturated carbon-carbon bonds usually requires the application of low-valent metal catalysts, which could cleave the propargylic ester linkage. Thus, it is desirable to identify a catalyst which could undergo cyclometallation without cleaving the propargylic ester linkage. In this paper, we used trans-RhCI(CO)(PPh3)2 to realize the cyclometallation of propargylic 2,3-dienoates. The substituents at the 4-position of allenoate moiety nicely control the reaction pathway: when the 4-position of propargylic 2,3-dienoate 1 was monosubstituted with an aryl group, the bicyclic intermediate 7 formed by the cyclometallation could highly selectively undergo carbometalation with the alkyne moiety in the second molecule of propargylic 2,3-dienoate 1 to afford metallabicyclic intermediates 8a or 8b. Subsequent reductive elimination would afford 9, which could undergo an intramolecular Diels-Alder reaction resulting in the formation of polycyclic bis(δ-lactone)-containing structures 2. The intermediate could be trapped by adding 3-methoxyprop-1-yne affording cyclization-aromatization product 4p highly selectively. If the substituent at the 4-positon of the 2,3-allenoate moiety has a β-H atom, sequential unimolecular cyclometallation/β-H elimination/reductive elimination occurs to afford cross-conjugated 5(Z)-alkylidene-4-alkenyl-5,6-dihydropyran-2-ones. The Z-stereochemistry of the exo double bond was determined by the cyclometallation. Some of the α,β-unsaturated δ-lactones could be easily converted to other synthetically useful compounds via reduction reaction, hydrogenation, and iodination/coupling protocol. [ABSTRACT FROM AUTHOR]

New functionalizations of indoles via palladium-catalyzed reaction of indoles and 2-acetoxymethyl-substituted electron-deficient alkenes are reported. It was found that for N-protected indoles the reaction proceeded smoothly in the presence of 5 mol % of Pd(acac)2 and 10 mol % of PPh3 at 80 °C in HOAc, while for N-unprotected indoles, the reaction was carried out by using 5 mol % of Pd(dba)2 or 2.5 mol % of Pd2(dba)3•CHCI3 with 10 mol % of 2,2′-bipyridine as the catalyst in toluene. This strategy allows the selective installation of electron-deficient olefin functionality at the 3-position of indoles, which might be difficult to obtain by other methods and can be further elaborated. [ABSTRACT FROM AUTHOR]

A highly regioselective Cu(I)-catalyzed anti-carbometallation of secondary terminal propargylic alcohols with 1° alkyl or aryl Grignard reagents affording 2-substituted allylic alcohols was developed. By using this method, optically active allylic alcohols can be prepared from the optically active propargylic alcohols without obvious loss of the enantiopurity. The cyclic organometallic intermediate formed may undergo an iodination or a Pd(0)-catalyzed coupling reaction to afford stereo-defined allylic alcohols. [ABSTRACT FROM AUTHOR]

A highly stereoselective iodolactonization of alkylidenecyclopropyl esters with iodine or N-iodosuccinimide (NIS) in aqueous CH3CN to afford 4,5-trans-1,5-cis-3-oxabicyclo-[3.1.0]hexane-2- ones is described. The reaction is very general, accommodating a wide range of substituents. A plausible mechanism that explains the essential role of water in this reaction is proposed. [ABSTRACT FROM AUTHOR]

The Pd(II)-catalyzed oxidative heterodimerization reaction of 2,3-allenamides and 1,2-allenyl ketones was studied. It provides an efficient route for the synthesis of the polysubstituted 4-(furan-3'-yl)-2(5H)-furanimines, which are not readily available from the known methods. Due to the application of benzoquinone, the loadings of both the palladium catalyst and ketone have been greatly reduced for the oxidative heterodimerization of 2,3-allenamides and 1,2-allenyl ketones in acetic acid. [ABSTRACT FROM AUTHOR]

Discusses the advances on the chemistry of allenes. Factors that led to the development of allene chemistry; Ability of allenes to demonstrate reactivities and selectivities; Mechanism of action of allenes and reactions with other organic compounds.

The PdCl2-catalyzed cyclocarbonylation reaction of propargylic amines with CuCl2 and benzoquinone afforded (E)-α-chloroalkylidene-β-lactams in moderate to good yields. The formation of the corresponding Z-isomers or five-membered products was not observed. The reaction of the readily available optically active prop argylic amines provides a convenient synthesis of the corresponding (E)-α-chloroalkylidene-β-lactams with high ee values. The structure and the stereochemistry of the products were established by the X-ray single-crystal diffraction study of (E)-6d and (E)-6e, which indicates that the stereoselectivity in this reaction is different from what was observed with propargylic alcohols. A rationale for this reaction was proposed. [ABSTRACT FROM AUTHOR]

A new method for highly regio- and stereoselec- tive synthesis of polysubstituted cyclopropane compounds via the Pd(0)-catalyzed coupling-cyclization reaction of 2-(2′,3′-allenyl)malonates with organic halides is described. In these reactions, the starting materials are easily available and the operation is convenient. The ratios of trans-isomer/ cis-vinylic cyclopropanes are up to 98:2. [ABSTRACT FROM AUTHOR]

The double ring-closing metathesis reaction of N-alkynyl-N-(1,ω)-alkadienyl acrylamides 1 using first- or second-generation Grubbs' catalyst afforded, in a highly selectively manner, the fused bicyclic quinolizidine alkaloid derivatives and their analogues bearing a 1,3-diene moiety, which may further undergo a Diels-Alder reaction with a dienophile to afford N-containing polycyclic compounds. The excellent selectivity of fused/dumbbell-mode cyclization has been realized by the higher reactivity of the electron-rich C=C bond or carbon-carbon triple bond combined with the lower reactivity of the electron-deficient C=C bond toward metallocarbenes and the thermodynamically more stable nature of fused bicyclic compounds 3 vs dumbbell-type bicyclic compounds 4. [ABSTRACT FROM AUTHOR]

It was observed that the halohydroxylation of 1,2-allenyl sulfides or selenides with Br2 (CuBr2 or NBS) or I2 and water demonstrated a fairly good regioselectivity (i.e., the C=C bond that is remote from the S or Se atom was halohydroxylated with the halogen atom connecting to the middle carbon atom and the hydroxyl group connecting to the non-S terminal carbon or Se-substituted terminal carbon atom of the allene moiety), leading to the synthesis of synthetically important 3-organosulfur or seleno-2-haloallylic alcohols. The stereoselectivity depends on the nature of X+ and S or Se, showing a Z-selectivity with the matched Lewis acid-base pair. [ABSTRACT FROM AUTHOR]

The K[sub 2]CO[sub 3] (10 mol %)-catalyzed 1,4-addition reaction of diethyl malonate with various substituted 1,2-allenic ketones leading to polyfunctionalized β,γ-unsaturated enones 3 or 4 was studied. With 3-unsubstituted 1-substituted-1,2-allenyl ketones, the highly selective formation β,γ-unsaturated enones 4 was observed; with 1,2-allenyl ketones bearing one or two 3-substituents in the allenyl group, only β,γ-unsaturated enones 3 with an unmigrated carbon-carbon double bond were produced; with 3-monosubstituted-1,2-allenyl ketones Z-β,γ-unsaturated enones 3 were formed with excellent stereoselectivity (E:Z > 96:4); with propadienyl ketones, mixtures of β,γ-unsaturated enones 3 and 4 were formed, α-Pyrone derivatives were synthesized via the K[sub 2]CO[sub 3]-catalyzed or -promoted reaction of 1,2-allenic ketones with diethyl malonate via a sequential Michael addition carbon-carbon double bond migration-lactonization process. [ABSTRACT FROM AUTHOR]

An effective method for the synthesis of β-allyl polysubstituted butenolides from the easily available allylic halides and 2,3-allenoic acids is described. By using this method optically active butenolides can be obtained. According to the results presented in this paper, the reaction may proceed via three consecutive steps: cyclic oxypalladation of the allene, insertion of the C=C bond in allylic halides, and β-dehalopalladation. [ABSTRACT FROM AUTHOR]

The palladium-catalyzed coupling-cyclization of α- or β-amino allenes with allylic halides leading to 3-allylic 2,5-dihydropyrroles and 1,2,3,6-tetrahydropyridines, respectively, was studied. The starting materials are easily available. The skeletons of both two classes of products were established by the X-ray diffraction studies of 7i and 9b. Through the study of the reaction of 2b with 3-chloro1-butene, 1-chloro-2-butene, and π-allyl palladium species and the stereochemical outcome of the coupling cyclization of (S)-2m and (R)-2n, it is believed that the current transformation most likely proceeded via a Pd(II)-catalyzed pathway, although a Pd(0) pathway cannot be completely excluded. [ABSTRACT FROM AUTHOR]

Twelve examples of 1,3,5-tribromo-2,4,6-trienylbenzenes were easily synthesized by alkylation, etherification, and amination methods. Under conditions A and B, a series of tetracycles with a benzene core, i.e., fused 5,6,6-, 6,6,6-, and 6,6,7-tetracyclic compounds, were prepared efficiently via this intramolecular triple Heck reaction protocol. [ABSTRACT FROM AUTHOR]

Under the catalysis of 1 mol % Pd(PPh[sub 3])[sub 4], the reaction of 4,4-disubstituted 2,3-allenamides and organic iodides in toluene afforded iminolactones stereospecifically in >90% yields using K[sub 2]CO[sub 3] (2 equiv) 5 mol % TBAB as the base. A similar reaction with 4-monosubstituted 2,3-allenamides afforded γ-hydroxy-γ-lactams in relatively lower yields. The N/O-attack selectivity may be determined by the steric effect at the 4-position of 2,3-allenamides. [ABSTRACT FROM AUTHOR]

Describes the synthesis of 2,5-dihydrofurans and 5,6-dihydro-2H-pyrans. Palladium-catalyzed cyclizative coupling reaction of 2,3- or 3,4-allenols with allylic halides; Role of allenol substituents on the outcome of the reactions; Cyclic oxypalladation of allenol.

Examines the control of regioselectivity in Pd(0)-catalyzed coupling-cyclization. Determination on the organic halides by steric and electronic effects; Regioselectivity of reaction; Stability of palladium intermediates.

Examines the patterns on the coupling reaction of allenic palladium reagents. Controlling factors on the regioselectivity of the coupling reaction; Methodology in the tuning of regioselectivity; Incompatibility of the synthesized products with the lithiation protocol.

Investigates the oxidative addition reaction of 1,1-dibromo-1-alkenes, alpha-dehalopalladation and the intramolecular bis(carbopalladation) reaction of alkenes. Synthesis of starting materials; Possibility of alpha-dehalopalladation and optimization of the reaction conditions; Scope of bicyclic carbopalladation reactions.

Studies the Pd(0)-catalyzed coupling reaction of electron-deficient alkenyl halides with the organozinc formed by the subsequent treatment of 1-phenylalk-1-yne with n-BuLi and ZnBr2 with or without a catalytic amount of HgCl2. Observation of both the allene-formation- and the alkyne-formation-type coupling reactions with high regio- and stereoselectivity.

Examines the preparation of heterocyclic compound beta-halobutenolides. Use of CuX2-mediated haloactonization reaction of 2,3-allenoic acids; Biological activities of beta-halobutenolides; Feasibility of halocyclization process; Proposal of a mechanism for process reaction; Effect of hydroxyl group intramolecular attack on copper.

Investigates the hydrohalogenation reaction of 1,2-allenyl ketones. Stereoselective synthesis of beta,omega-unsaturated beta-haloketones; Hydroiodination reaction of 3,4-pentadien-2-one; Conversion of the carbon-halogen bond, the carbonyl group, and the carbon-carbon double bond to other functional groups.

A highly regioselective indium-mediated allylation of carbon dioxide starting from simple allylic halides (X = I, Br, Cl) has been developed. No transition metal catalyst is needed and an inert atmosphere is not necessary. The reaction tolerates a wide range of synthetically attractive functional groups with a very high branched regioselectivity. [ABSTRACT FROM AUTHOR]

Propiolaldehyde was prepared by the oxidation of propargyl alcohol using molecular oxygen as the oxidant under atmospheric pressure and room temperature in a decent yield. Compared to the previous method with CrO3, such a protocol avoids the use of a stoichiometric amount of oxidant, and the workup procedure is much more eco-friendly and convenient affording a higher yield of the product. [ABSTRACT FROM AUTHOR]

In this paper, we developed a new bisoxazoline ligand with a spiro skeleton and a α-naphthylmethyl substituent, i.e. (Ra,S,S)-L3, which has been successfully applied to the highly enantioselective cyclic allylation based on the carbopalladation of 3,4-allenyl hydrazines with ee values ranging from 92-95%. [ABSTRACT FROM AUTHOR]

2,3-Dihydro-1H-pyrazoles were highly selectively synthesized via the Pd(0)-catalyzed coupling-cyclization reaction of 4-non-substituted 2-substituted 2,3-allenyl hydrazines with aryl iodides in moderate to good yields. [ABSTRACT FROM AUTHOR]

In this paper a new cycloisomerization pattern of 1,5-bisallenes based on the catalyst and substituent effects has been reported. A range of seven-membered cross-conjugated trienes 7would be obtained efficiently via the -H elimination and reductive elimination of the intermediates formed via cycloisomerization. [ABSTRACT FROM AUTHOR]

Highly chemo- and regioselective Pd(0)-catalyzed coupling−cyclization of 2-(2‘,3‘-allenyl)acetylacetates with organic halides using K3PO4as base in DMF efficiently afforded 4,5-dihydrofuran derivatives in moderate to excellent yields, with a selectivity of >97:3. [ABSTRACT FROM AUTHOR]

An introduction is presented that discussed issues on topics the substantial improvement in the quality of manuscripts; types of manuscripts including Inside Story and Emerging Topic that launched to meet the need of wide readership along with special thanks to authors and referees.

A highly regio- and stereoselective palladium(0)-catalyzed addition of organoboronic acids with 1,2-allenylphosphonates in the presence of HOAc forming tri- or tetrasubstituted 1(E)-alkenylphosphonates is reported in this paper. The stereo-selectivity is much higher than the reported cases. The effects of different R¹, R², and R³ were studied. A mechanism of this reaction is proposed on the basis of our previous study. [ABSTRACT FROM AUTHOR]

Under different reaction conditions, 1,1-diarylpropadienes and 1,3-diarylpropynes can be prepared respectively by the sequential lithiation of 1-aryl-l-propynes, transmetalation, and the corresponding Pd(0)-catalyzed cross-coupling with aryl halides. A rationale for the formation of 1,3-diarylpropynes is proposed. [ABSTRACT FROM AUTHOR]

Examines the structure of an efficient I−-catalyzed methyl-oxygen bond cleavage in 2-methoxyfurans. Result of the X-ray diffraction study of the structure of this compound; Effects of solvent on the reaction of 2-methoxy-3-methoxycarbonyl-5-phenylfuran and allylic iodide; General procedure for NaI-catalyzed reaction of 2-methoxyfuran with organic iodides.

4-Halo-5-hydroxyfuran-2(5H)-ones were synthesized via the efficient sequential halolactonization-hydroxylation reaction of 4-aryl-2,3-allenoic acids with I2 or CuX2 (X = Br or Cl) in moderate to good yields. The structures of the products were established by the X-ray single-crystal diffraction study of 3-methyl-4-iodo-5-phenyl-5-hydroxyl2(5H)-furanone (2a). A rationale for this reaction was discussed based on some brief mechanistic study. [ABSTRACT FROM AUTHOR]

Demonstrates the hydrohalogenation reactions of 1,2-allenic sulfones. Synthesis of 2-haloallylic sulfones; Use of metallic halides in the hydrohalogenation reaction of 1,2-allenic sulfones; Chemistry in the preparation of 1,2-allenic sulfones.

The article discusses the application of a mediated protocol on the one-spot synthesis of disubstituted allenes from alkynes, morpholine, and aldehydes. It states that the protocol reveals that the allenes are formed in 36% yield, and that the aliphatic aldehydes can be used when the temperature needs to be increased or the time must be extended. It also mentions that the terminal propargylic alcohols' reaction corresponds to allenols.

Studies trisubstituted furans. Properties of carbocyclic molecules cyclopropenes; Examples of regioselective transformation.

The CuBr2-catalyzed enantioselective allenylation of terminal alkynols with carbon chains of different lengths has been developed. Compared with (S)-α,α-diphenylprolinol, the reaction using (S)-α,α-dimethylprolinol as the chiral amine afforded optically active 1,3-disubstuted allenols with higher ee-values. Both aliphatic and aromatic aldehydes could be applied. The naturally occurring phlomic acid was synthesized in four steps from commercially available hex-5-yn-1-ol. [ABSTRACT FROM AUTHOR]

Provides information on a study which examined the synthesis of 3-halo-3-butenols, prepared from 2-halo-2-propenyl ketones. Effectiveness of sodium halides; In-depth look at the treatment of crotonic acids; Methodology used to conduct the study; Results of the study.

Studies the mechanism of anti-carbometalation of homopropargyl alcohols and their higher homologues. Differences in the ease and scope between stereoisomerization of the omega-alkynols and its derivative; Preferential formation of an eight membered aluminacycle.

Oxidation from alcohols to carboxylic acids, a class of essential chemicals in daily life, academic laboratories, and industry, is a fundamental reaction, usually using at least a stoichiometric amount of an expensive and toxic oxidant. Here, an efficient and practical sustainable oxidation technology of alcohols to carboxylic acids using pure O2 or even O2 in air as the oxidant has been developed: utilizing a catalytic amount each of Fe(NO3)3·9H2O/TEMPO/MCl, a series of carboxylic acids were obtained from alcohols (also aldehydes) in high yields at room temperature. A 55 g-scale reaction was demonstrated using air. As a synthetic application, the first total synthesis of a naturally occurring allene, i.e., phlomic acid, was accomplished. [ABSTRACT FROM AUTHOR]

A cadmium iodide mediated tandem reaction involving amine and two molecules of terminal alkynes for the synthesis of trisubstituted allenes has been developed. By applying this protocol, methyl-substituted allenes may be obtained easily from two molecules of terminal alkynes and pyrrolidine via methyl ketoniminium and propargylic amine formation, 1,5-hydride transfer and β-elimination. [ABSTRACT FROM AUTHOR]