- Relative Migratory Aptitudes of Alkyl Groups in the Iodination of Lithium Ethynyltrialkylborates
-
Relative migratory aptitudes of various alkyl groups have been determined in the iodine-induced rearrangement of lithium ethynyltrialkylborates.Trialkylboranes of types R3-nBR'n and thexyl-BRR' were complexed with lithium acetylide-ethylenediamine.Iodination, followed by deiodoboration of the rearranged intermediates, produced 1-alkynes in amounts which depend, after statistical correction, on the relative rates of alkyl group migration in an intramolecular competition.In some cases, the migratory aptitude was found to depend on the alkyl substitution pattern in the organoborate.The overall migratory aptitude order is bicyclooctyl > n-butyl > cyclohexyl, isobutyl, sec-butyl > thexyl.When the secondary and primary migrating carbon series are considered separately, the order is consistently bicyclooctyl > cyclohexyl > sec-butyl, and n-butyl > isobutyl.
- Slayden, Suzanne W.
-
-
Read Online
- Potassium Dimesitylphosphinite Catalyzed Intermolecular Hydrophosphorylation of Alkynes
-
In this investigation we evaluated the scope of the intermolecular hydrophosphorylation (Pudovik reaction) of alkynes R1-C-C-R2 (R1 = H, alkyl, Ph; R2 = alkyl, Ph, COOMe, SiMe3, Si(iPr)3) with bis(2,4,6-trimethylphenyl)phosphane oxide (dimesitylphosphane oxide, Mes2P(O)H) in tetrahydrofuran at room temperature or 65 °C, catalyzed with 5 or 10 mol % of potassium dimesitylphosphinite (Mes2P-O-K), yielding alkenyldimesitylphosphane oxides (Mes2P(O)-C(R1)=C(H)R2). This procedure requires substituents with a -I effect at the C-C triple bond, whereas alkyl-substituted alkynes are inactive under these reaction conditions. The hydrophosphorylation proceeds regioselectively, but E/Z isomer mixtures are obtained. E/Z isomerization occurs at elevated temperatures with an estimated energy barrier of 59 kJ mol-1 (R1 = Me; R2 = Ph). Trimethylsilyl substituents at the alkyne functionality (R1 = H, nBu; R2 = SiMe3) destabilize the product, leading to degradation and formation of Mes2P-O-SiMe3 and R1-C-C-H.
- H?rling, Stephan M.,Fener, Benjamin E.,Krieck, Sven,G?rls, Helmar,Westerhausen, Matthias
-
-
Read Online
- Method for synthesizing terminal alkyne by utilizing 1, 2-dihaloalkane
-
The invention discloses a method for synthesizing terminal alkyne by utilizing 1, 2-dihaloalkane. According to the method, 1, 3-dihaloalkane is used as a raw material and terminal alkyne is synthesized under the action of alkali and a catalyst, wherein the molar ratio of the alkali to the 1, 2-dihaloalkane is 2: 1-5: 1, the use amount of the catalyst is 2%-10% of the mass of the 1, 2-dihaloalkane,the reaction temperature is 100-150 DEG C and the reaction time is 3-10 h. The method has the advantages of environmental protection, high selectivity, high yield and the like.
- -
-
Paragraph 0022-0024
(2020/04/29)
-
- Palladium-Catalyzed Cascade Intramolecular Cyclization and Allylation of Enynoates with Allylic Alcohols
-
A Pd(II)-catalyzed mild and highly regioselective 6-endo cyclization/allylation reaction of enynoates with simple allylic alcohols has been developed. Under mild reaction conditions, the vinyl palladium species generated in situ after cyclization could insert C-C double bond of allylic alcohol through cross-coupling reaction and lead to the formation of allyl pyrone via β-OH elimination. This cascade cross-coupling reaction represents a direct and atom economic methodology for the construction of novel allyl pyrones in moderate to good yields.
- Qiu, Sheng-Qi,Ahmad, Tanveer,Xu, Yun-He,Loh, Teck-Peng
-
p. 6729 - 6736
(2019/06/14)
-
- Na2S-mediated synthesis of terminal alkynes from: Gem -dibromoalkenes
-
The Na2S-mediated facile synthesis of terminal alkynes from gem-dibromoalkenes, at 20/40 °C under open flask conditions has been developed. Various precursors derived from heteroaromatic/aromatic/aliphatic aldehydes were found compatible. The reaction is proposed to proceed through the Fritsch-Buttenberg-Wiechell (FBW) rearrangement involving the corresponding vinyl carbene. Using mild reaction conditions with inexpensive Na2S·9H2O under air atmosphere has significant advantages over earlier routes.
- Singh, Radhey M.,Nandini, Durgesh,Bharadwaj, Kishor Chandra,Gupta, Tanu,Singh, Raj Pal
-
p. 9979 - 9982
(2017/12/26)
-
- AGRICULTURAL PHEROMONE COMPOSITIONS COMPRISING POSITIONAL ISOMERS
-
The present disclosure provides pheromone compositions. In some aspects, the compositions taught herein comprise a pheromone chemically corresponding to the pheromone naturally produced by a given insect, along with at least one positional isomer of said pheromone. In various aspects, pheromone compositions of the present disclosure are able to modulate the response of the insect based on the ratio of natural pheromone to its positional isomer.
- -
-
Paragraph 0368
(2017/06/12)
-
- Lanthanide-Catalyzed Reversible Alkynyl Exchange by Carbon–Carbon Single-Bond Cleavage Assisted by a Secondary Amino Group
-
Lanthanide-catalyzed alkynyl exchange through C?C single-bond cleavage assisted by a secondary amino group is reported. A lanthanide amido complex is proposed as a key intermediate, which undergoes unprecedented reversible β-alkynyl elimination followed by alkynyl exchange and imine reinsertion. The in situ homo- and cross-dimerization of the liberated alkyne can serve as an additional driving force to shift the metathesis equilibrium to completion. This reaction is formally complementary to conventional alkyne metathesis and allows the selective transformation of internal propargylamines into those bearing different substituents on the alkyne terminus in moderate to excellent yields under operationally simple reaction conditions.
- Shao, Yinlin,Zhang, Fangjun,Zhang, Jie,Zhou, Xigeng
-
supporting information
p. 11485 - 11489
(2016/10/24)
-
- SYNTHESIS OF OLEFINIC ALCOHOLS VIA ENZYMATIC TERMINAL HYDROXYLATION
-
In certain aspects, the present invention provides methods for producing terminally hydroxylated alkenes and alkynes by contacting an unsaturated or saturated hydrocarbon substrate with a hydroxylase enzyme. Exemplary terminal hydroxylases useful for carrying out the methods of the invention exhibit strong selectivity towards one terminal carbon of a hydrocarbon substrate and include, but are not limited to, non-heme diiron alkane monooxygenases, cytochromes P450 (e.g., cytochromes P450 of the CYP52 and CYP153 family), as well as long chain alkane hydroxylases. In some embodiments, the terminally hydroxylated alkene or alkyne is further converted to a terminal alkenal. In certain embodiments, terminally hydroxylated alkenes and alkynes are useful as insect pheromones which modify insect behavior. In other embodiments, terminally hydroxylated alkenes and alkynes are useful intermediates for producing pheromones via acetylation or oxidation of the alcohol moiety.
- -
-
Paragraph 0286; 0287
(2016/01/30)
-
- Catalytic and computational studies of N-heterocyclic carbene or phosphine-containing copper(I) complexes for the synthesis of 5-iodo-1,2,3-triazoles
-
Two complementary catalytic systems are reported for the 1,3-dipolar cycloaddition of azides and iodoalkynes. These are based on two commercially available/readily available copper complexes, [CuCl(IPr)] or [CuI(PPh 3)3], which are active at low metal loadings (PPh 3 system) or in the absence of any other additive (IPr system). These systems were used for the first reported mechanistic studies on this particular reaction. An experimental/computational-DFT approach allowed to establish that (1) some iodoalkynes might be prone to dehalogenation under copper catalysis conditions and, more importantly, (2) two distinct mechanistic pathways are likely to be competitive with these catalysts, either through a copper(III) metallacycle or via direct-activation of the starting iodoalkyne.
- Lal, Steven,Rzepa, Henry S.,Diez-Gonzalez, Silvia
-
p. 2274 - 2287
(2014/07/21)
-
- Reactions of perfluorinated alkenyl-, alkynyl-, alkyltrifluoroborates, and selected hydrocarbon analogues with the halogenating agents Hal2 (Hal = F, Cl, Br), "brF" (BrF3-Br2 1:1), and ICl
-
Reactions of [Bu4N][RBF3] [R = CnF 2n+1CF=CF (cis, trans), CF2=CF, CF2=C(CF 3), trans-C4H9CF=CF, trans-C6H 5CF=CF, C4H9CH=CH (cis, trans), CF 3C≡C, and C4H9C≡C] with chlorine, bromine, BrF3 + Br2 (as equivalent of "BrF"), and ICl in solution (CH2Cl2, CHCl3, CF 3CH2CF2CH3) led to 1, 2-addition of halogen and/or replacement of boron by halogen (halodeboration). The reaction of [Bu4N][CF3C≡CBF3] with less than equimolar amounts of diluted fluorine (5 %) in 1, 1, 1, 3, 3-pentafluorobutane (PFB) showed only [Bu4N][CF3CF2CF 2BF3] as fluorine addition product besides extensive fluorodeboration. Suspensions of the insoluble K[CF2=CFBF 3] salt reacted with Cl2 and Br2 in CH 2Cl2 giving preferentially products of halogen addition across the C=C bond. In reactions with ICl iododeboration with formation of CF2=CFI occurred besides 1, 2-addition with formation of [CF 2I-CFClBF3]-. The halodeboration reaction of[Bu4N][trans-C4H9CF=CFBF3] with Br2, "BrF", and ICl, of K[trans-C6H 5CF=CFBF3] with Br2, and of [Bu 4N][trans-C4F9CF=CFBF3] with ICl proceeded stereospecifically. Copyright
- Bardin, Vadim V.,Adonin, Nicolay Yu.,Frohn, Hermann-Josef
-
p. 565 - 579
(2012/05/20)
-
- Reactions of fluoroalk-1-en-1-yltrifluoroborate and perfluoroalk-1-yn-1- yltrifluoroborate salts and selected hydrocarbon analogues with hydrogen fluoride and with halogenating agents in aHF and in basic solvents
-
The relative rate of the electrophilic hydrodeboration of K[R′BF 3] with HF (27-100%) diminishes in the series R′ = C 4H9CC > C4F9CFCFCC > CF 2C(CF3) > C3F7CC ～ (CF 3)2CFCC > CF3CC. When R′ = CF 3CC the new salt K[CF3CH2-CF2BF 3] was obtained by addition of HF besides CF3CCH and K[BF4]. Small amounts of water caused the formation of K[CF 3CH2-C(O)BF3] as a by-product. The electrophilic halofluorination of perfluoroalkenyltrifluoroborate salts with NCS or NBS in aHF (anhydrous HF) led to K[RFCFHal-CF2BF 3] (from K[RFCFCFBF3]) and K[R FCHal2-CF2BF3] (from K[R FCHalCFBF3] and K[RFCCBF3]) (Hal = Cl, Br). Treatment of K[RFCFCFBF3] and K[R FCCBF3] with 5% F2/N2 in MeCN gave the corresponding salts K[RFCF2-CF2BF 3] in 16-25% isolated yield. Reactions of K[trans-C4F 9CFCFBF3] with Cl2 in MeOH resulted in K[C 4F9CFCl-C(O)BF3] (major product). The latter was also obtained in reactions of K[trans-C4F9CFCFBF 3] with Cl2 in MeCN or sulfolane after sequential methanolysis of the primarily formed products. In contrast, the salts K[RCFCFBF3] (R = CnF2n+1, trans-C 4H9) and K[CF3CCBF3] underwent bromodeboration to RCFCFBr and CF3CCBr, respectively, when they were reacted with bromine in the polar solvents MeOH, MeCN, or sulfolane.
- Bardin, Vadim V.,Adonin, Nicolay Yu.,Frohn, Hermann-Josef
-
experimental part
p. 114 - 128
(2012/04/10)
-
- Rapid consecutive three-component coupling-Fiesselmann synthesis of luminescent 2,4-disubstituted thiophenes and oligothiophenes
-
(Hetero)aroyl chlorides, alkynes, and ethyl 2-mercapto acetate can be reacted in a consecutive three-component synthesis to give 2,4-disubstituted thiophene 5-carboxylates in good to excellent yields. In the sense of a pseudo-five-component reaction highly blue luminescent symmetrical terthiophenes and a quinquethiophene can be synthesized in excellent yield.
- Teiber, Marco,Mueller, Thomas J. J.
-
supporting information; experimental part
p. 2080 - 2082
(2012/03/10)
-
- Removal of water - a factor influencing the synthesis of alkynes in a phase-transfer catalyzed β-elimination reaction
-
Acetylene derivatives 4 were synthesized from the corresponding vicinal bromo compounds 2 in the phase-transfer catalyzed hydrogen bromide β-elimination reaction using solid potassium hydroxide as a base, xylene as a solvent, and a phase-transfer catalyst. The yields of the synthesized acetylene derivatives 4 were substantially improved when water formed in the process had been removed.
- Zakrzewski,Huras,Sas,Zelechowski,Bombinska
-
p. 1051 - 1057
(2008/09/21)
-
- Manganese- or iron-catalyzed homocoupling of grignard reagents using atmospheric oxygen as an oxidant
-
Atmospheric oxygen was used for the first time as an oxidant in metal-catalyzed homocoupling of Grignard reagents. These manganese- or iron-catalyzed reactions are efficient, cheap, and eco-friendly. They are applicable to the large-scale synthesis of symmetrical conjugated compounds. Copyright
- Cahiez, Gerard,Moyeux, Alban,Buendia, Julien,Duplais, Christophe
-
p. 13788 - 13789
(2008/04/11)
-
- Unique σ-bond metathesis of silylalkynes promoted by an ansa-dimethylsilyl and oxo-bridged uranium metallocene
-
The tetrachloride salt of uranium reacts with 1 equiv of the lithium ligand Li2[(C5Me4)2SiMe2] in DME to form the complex [η5-(C5Me4)2SiMe2]UCl2·2LiCl·2DME (1), which undergoes a rapid hydrolysis in toluene to yield the dimeric bridged monochloride, monooxide complex [{[η5-(C5Me4)2SiMe2]UCl}2(μ-O)(μ-Cl)?Li?1/2DME]2 (2). Metathesis of 2 with BuLi in DME gives the mono-bridged dibutyl complex {[η5-(C5Me4)2SiMe2]UBu}2(μ-O) (3). Complex 2 was characterized by solid-state X-ray analysis. Complex 3 was found to be an active catalyst for the disproportionation metathesis of TMSC≡CH (TMS = SiMe3) and the cross-metathesis of TMSC≡CH or TMSC≡CTMS with various terminal alkynes. The metathesis of TMSC≡CH gives TMSC≡CTMS and HC≡CH, whereas the cross-metathesis of TMSC≡CH or TMSC≡CTMS with terminal alkynes (RC≡CH) yields TMSC≡CTMS, TMSC≡CR, and HC≡CH. In addition, TMSC≡CCH3 also was found to react with tBuC≡CH, yielding TMSC≡CBut and CH3C≡CH. A plausible mechanism for the catalytic process is presented. Copyright
- Wang, Jiaxi,Gurevich, Ylia,Botoshansky, Mark,Eisen, Moris S.
-
p. 9350 - 9351
(2007/10/03)
-
- A new, efficient method for direct α-alkenylation of β-dicarbonyl compounds and phenols using alkenyltriarylbismuthonium salts
-
Direct α-alkenylation of β-keto esters, β-diketone, and phenols with alkenyltriarylbismuthonium salts proceeded smoothly in the presence of 1,1,3,3-tetramethylguanidine to afford the corresponding α-alkenylated carbonyl compounds (β,γ-unsaturated carbonyl compounds) in good yields. The high leaving ability of the triarylbismuthonio group is a key driving force to achieve the C-C bond formation at the vinylic carbon under mild conditions.
- Matano, Yoshihiro,Imahori, Hiroshi
-
p. 5505 - 5508
(2007/10/03)
-
- Preparation of preparing substituted indanones
-
a process for the preparation of indanones of the formula II from, indanones of the formula I or of indanones of the formula IIa from indanones of the formula Ia comprises reacting an indanone of the formula I or Ia with a coupling component.
- -
-
-
- Flash vacuum pyrolysis over magnesium. Part 1 - Pyrolysis of benzylic, other aryl/alkyl and aliphatic halides
-
Flash vacuum pyrolysis over a bed of freshly sublimed magnesium on glass wool results in efficient coupling of benzyl halides to give the corresponding bibenzyls. Where an ortho halogen substituent is present further dehalogenation gives some dihydroanthracene and anthracene. Efficient coupling is also observed for halomethylnaphthalenes and halodiphenylmethanes while chlorotriphenylmethane gives 4,4′-bis(diphenylmethyl)biphenyl. By using α,α′-dihalo-o-xylenes, benzocyclobutenes are obtained in good yield, while the isomeric α,α′-dihalo-p-xylenes give a range of high thermal stability polymers by polymerisation of the initially formed p-xylylenes. Other haloalkylbenzenes undergo largely dehydrohalogenation where this is possible, in some cases resulting in cyclisation. Deoxygenation is also observed with haloalkyl phenyl ketones to give phenylalkynes as well as other products. With simple alkyl halides there is efficient elimination of HCl or HBr to give alkenes. For aliphatic dihalides this also occurs to give dienes but there is also cyclisation to give cycloalkanes and dehalogenation with hydrogen atom transfer to give alkenes in some cases. For 5-bromopent-1-ene the products are those expected from a radical pathway but for 6-bromohex-1-ene they are clearly not. For 2,2-dichloropropane and 1,1-dichloropropane elimination of HCl occurs but for 1,1-dichlorobutane, -pentane and -hexane partial hydrolysis followed by elimination of HCl gives E, E-, E,Z- and Z,Z- isomers of the dialk-1-enyl ethers and fully assigned 13C NMR data are presented for these. With 6-chlorohex-1-yne and 7-chlorohept-1-yne there is cyclisation to give methylenecycloalkanes and -cycloalkynes. The behaviour of 1,2-dibromocyclohexane and 1,2-dichlorocyclooctane under these conditions is also examined. Various pieces of evidence are presented that suggest that these processes do not involve generation of free gas-phase radicals but rather surface-adsorbed organometallic species.
- Aitken, R. Alan,Hodgson, Philip K.G.,Morrison, John J.,Oyewale, Adebayo O.
-
p. 402 - 415
(2007/10/03)
-
- Carbon-halogen bond activation by Nickel catalyst: Synthesis of alkenes, from 1,2-dihalides
-
Unsaturated hydrocarbons can easily be prepared in a few seconds starting from 1,2 dibromides in the presence of a catalytic amount of Nickel diphenylphosphinoethane dichloride (NidppeCl2) and tri.n.butyl tin hydride, (TBTH) at room temperature. The dependencie of the nature of starting dihalides is investigated.
- Malanga, Corrado,Mannucci, Serena,Lardicci, Luciano
-
p. 1021 - 1028
(2007/10/03)
-
- Isomerization of terminal alkynes catalyzed by itterbium(II)-aromatic imine complexes
-
Ytterbium-aromatic imine dianion complexes 2, which can easily be prepared from metallic ytterbium and aromatic imines 1, can act as effective catalysts for the isomerization of terminal alkynes 3 under mild conditions to afford internal alk-2-ynes 4 in good yields.In the reaction of 1-hexene 3a, 2-hexyne 3a, 2-hexyne 4a can be simply obtained by trap-to-trap distillation and the catalytic system can be reused for the isomerization of 3a without other treatments. - Keywords: lanthanoid-imine complex; terminal alkyne; isomerization; alk-2-yne
- Makioka, Yoshikazu,Taniguchi, Yuki,Kitamura, Tsugio,Fujiwara, Yuzo,Saiki, Akira,Takaki, Ken
-
p. 349 - 356
(2007/10/03)
-
- Synthesis and Nuclear Magnetic Resonance Studies on a Series of Synthesis Long-chain Tellurophene Fatty Esters
-
The synthesis and the results of the 1H and 13C NMR spectroscopic analyses of thirteen 2,5-disubstituted tellurophene fatty esters, containing substituents of different chain lengths, and of a monosubstituted tellurophene ester are repported.The tellurophene esters are obtained by cyclization of the corresponding conjugated intermediates with Na2Te in the presence of AgOAc in methanol.The tellurophene moiety in the alkyl chain induces a deshielding effect on the protons of the adjacent methylene prtons.The shift parameters of the tellurophene moiety on the shifts of the adjacent methylene carbon atoms are also determined.
- Jie, Marcel S. F. Lie Ken,Chau, Sherman H.
-
p. 2642 - 2657
(2007/10/03)
-
- STEREOSPECIFIC SYNTHESIS OF COMPONENTS OF THE NATURAL SEX PHEROMONE OF Pectinophora gossypiella
-
A multistage stereospecific synthesis of components of the natural pheromone was realized.Conditions were found for stereospecific trans-reduction of the triple bonds.A procedure was developed for regiospecific dehydrohalogenation of 1,2-dibromoalkanes.Conditions giving the Z and E isomers in ratio of 96 : 4 were found for the Wittig reaction.
- Matveeva, E. D.,Kvasha, M. P.,Kurts, A.L.
-
p. 1017 - 1021
(2007/10/02)
-
- Platinum Complex Catalyzed Carbonylation of Organic Iodides: Effective Carbonylation of Organic Iodides Having β-Hydrogens on Saturated sp3 Carbons
-
Dichlorobis(triphenylphosphine)platinum(II) is an effective catalyst precursor for the carbonylation of organic iodides having β-hydrogens on saturated sp3 carbons.The carbonylation under carbon monoxide pressure in the presence of alcohol gives esters, and aldehydes are obtained by the reaction under carbon monoxide and hydrogen pressure.Thus, 1-iodohexane is carbonylated to methyl heptanoate in 79percent yield in the presence of methanol at 120 deg C under 70 kg cm-2 of initial carbon monoxide pressure.Heptanal is formed in 86percent yield from 1-iodohexane at 120 deg Cunder carbon monoxide (50 kg cm-2) and hydrogen (50 kg cm-2).Alkenyl und alkynyl iodides are also smoothly carbonylated in the presence of alcohol into the corresponding esters without reduction of unsaturated bonds.
- Takeuchi, Ryo,Tsuji, Yasushi,Fujita, Masayuki,Kondo, Teruyuki,Watanabe, Yoshihisa
-
p. 1831 - 1836
(2007/10/02)
-
- Studies on the Thermal Conversion of Long-chain Alkynes at High Temperatures in the Gas Phase
-
In the gas phase pyrolysis of long-chain alkynes C5 to C9 at 773 to 873 K, a remarkable portion of molecular reaction (retro-ene analogous decompositions as well as cycloisomerizations of the parent alkynes to cyclopentenes alkylated in 3-position) takes place besides the thermal conversion of the starting compounds via radical chain processes.The different products were separated by GC and the main products identified by means of different methods.The mechanisms of formation of the major products are discussed.
- Ondruschka, B.,Zimmermann, G.,Ziegler, U.,Kopinke, F.-D.,Teuber, M.
-
p. 273 - 284
(2007/10/02)
-
- Methyl Group Migration in the Reactions of Alkynyltrialkylborates
-
It is shown that the methyl group cannot be used as a cheap, non-migrating group in the reactions of alkynyltrialkylborates with electrophiles.However, trimethylborane can be used as a methylboronating agent for alkynes, given the right choice of solvent, and this may be of use in terpene synthesis.
- Pelter, Andrew,Drake, Robert A.
-
p. 4181 - 4184
(2007/10/02)
-
- On 1.2-Shift Reactions and C-H-Insertions of Acyclic Alkylidene Carbenes
-
Two series of acyclic terminal vinyl bromides (1...4 and 5...7) were tested in the reaction with potassium tert-butoxide as precursors of alkylidene carbenes.As expected 1 up to 4 only give 1-alkynes whereas the 2-methylated vinyl bromides 5, 6 and 7 yield 1-methylated cyclopentenes predominantly besides 2-alkynes.The formation of cyclopentenes indicates a reaction route via alkylidene carbenes and 1,5-C-H-insertion reactions, that of 2-alkynes is convincing evidence for 1,2-alkyl shift reactions in 2-methyl substituted alkylidene carbenes.The selectivity of 1,5-C-H-insertion depends on the degree of alkyl substitution of the C-5-atom.At 240 deg C the selectivity is 1deg:2deg:3deg ca. 1:54:240.
- Ondruschka, Bernd,Remmler, Matthias,Zimmermann, Gerhard,Krueger, Christian
-
-
- Stereoselective Bifunctionalization of Alkynes by Means of the Mercury(II) Salt-Iodine Combination
-
The reaction of alkynes with iodine and mercury(II) salts (chloride, acetate, methanesulphonate, toluene-p-sulphonate, benzylsulphide, toluene-p-sulphinate, and thiocyanate) affords stereoselectively E-β-functionalized vinyl iodides resulting from the ionic addition of iodine and the mercury(II) salt anion.Unsymmetrical alkynes yield regiospecifically Markovnikov addition products.In the case of mercury(II) thiocyanate the reaction can be used also for the stereoselective preparation of E-1,2-dithiocyanatoalkenes.An ionic mechanism is proposed according to the observed regio- and stereochemistry.
- Barluenga, Jose,Martinez-Gallo, Jose M.,Najera, Carmen,Yus, Miguel
-
p. 1017 - 1020
(2007/10/02)
-
- Rates of Base-Catalyzed Hydrogen Exchange of Terminal Acetylenes in Aqueous Solution. Absence of Resonance Interaction
-
Rates of detritiation of 13 monosubstituted acetylenes labeled at the acetylenic hydrogen position were measured in aqueous amine buffer solution at 25 deg C, and hydroxide ion catalytic coefficients were evaluated.These rate constants, plus a few additional values from the literature, give a good correlation against inductive or field substituent constants: log(kHO-/M-1s-1) = 1.46+/-0.12 + (8.00+/-0.50)?I.This correlation is not improved by addition of resonance substituted constants, and the coefficients of the resonance term in two different dual parameter (resonance plus field) treatments of the data are in fact zero.
- Kresge, A. J.,Powell, M. F.
-
p. 819 - 822
(2007/10/02)
-
- DIOLS AS EFFECTIVE COCATALYSTS IN THE PHASE TRANSFER CATALYZED PREPARATION OF 1-ALKYNES FROM 1,2-DIHALIDES
-
Bis-tertiary diols accelerate bis-eliminations of HX from 1,2-dihalides in the presence of an onium salt as phase transfer catalyst and potassium hydroxyde as base.PEG 400 catalyzes the same elimination, but isomerizations from 1-alkyne to mixtures with the 2-alkyne and the 1,2-diene occur easily.
- Dehmlow, Eckehard V.,Thieser, Rainer,Sasson, Yoel,Neumann, Ronny
-
p. 3569 - 3574
(2007/10/02)
-
- Vinylic Organoboranes. 1. A Convenient Synthesis of Acetylenes via the Reaction of Lithium (1-Alkynyl)organoborates with Iodine
-
Lithium (1-alkynyl)organoborates, readily prepared from organoboranes and lithium acetylides, undergo a facile reaction at low temperature with iodine to for internal acetylenes in high yield.Unlike conventional methods for the preparation of acetylenes via nucleophilic displacement, the reaction is applicable to both primary and secondary as well as aromatic and functionally substituted groups.The use of lithium acetylide-ethylenediamine form the formation of the organoborate extends the reaction to terminal acetylenes.This reaction occurs with complete retention of the configuration about the boron-carbon bond.The procedure, with its exceptionally broad applicability, provides a simple, general route to internal and terminal acetylenes.
- Suzuki, Akira,Miyaura, Norio,Abiko, Shigeo,Itoh, Mitsuomi,Midland, M., Mark,et al.
-
p. 4507 - 4511
(2007/10/02)
-
- Selective Synthesis of Alkynes by Catalytic Dehydrogenation of Alkenes over Polymer-supported Palladium Acetate in the Liquid Phase
-
A heterogenized palladium acetate catalyst, in the presence of oxygen and perchloric acid in ethanol-water caused the direct conversion of terminal and internal monoalkenes into the corresponding alkynes, under mild conditions and in high yields; Wacker-type ketonization occurs with the same reagents in dioxane-water.
- Cum, Giampietro,Gallo, Raffaele,Ipsale, Salvatore,Spadaro, Agatino
-
p. 1571 - 1573
(2007/10/02)
-
- Direct Photolysis of 1-Halo-1-hexynes. Lack of Ionic Behavior
-
Direct photolyses at >200 nm of 1-bromo- and 1-iodo-1-hexynes were performed in polar and nonpolar solvents.Only radical-derived products were obtained even in polar solvents, contrary to the previously reported ionic photochemical behavior of alkyl and vinyl halides.The results are discussed from an energy point of view; the ionization potential of the initially formed organic radical well accounts for the obvious difference in photobehavior between alkynyl and alkyl or vinyl halides.
- Inoue, Yoshihisa,Fukunaga, Takao,Hakushi, Tadao
-
p. 1732 - 1737
(2007/10/02)
-
- ORGANOMETALLICS, PART VII. THE SYNTHESIS OF α,α-DISUBSTITUTED METHYL ETHERS BY REACTION OF ETHYLDIPHENYLORTHOFORMATE WITH ORGANOMAGNESIUM COMPOUNDS
-
The reaction conditions are investigated for the production of pure α,α-disubstituted methyl esters.Crotyl- and ethyl-magnesium bromides on reaction with ethyldiphenylorthoformate in ether, under reflux conditions, yielded mixtures of mono- and disubstituted ethers; the former with total allylic transposition.Crotyl Grignard, at room temperature, gave only the monosubstituted mixed acetal.Acetylenic organomagnesiums produced high yields of pure α,α-disubstituted methyl ethers when the solvent was dichloromethane.Methyl vinyl and isopropenyl vinyl organomagnesiums in THF gave only disubstituted ethers.The products obtained are rationalized in terms of a mechanism incorporating a two-fold nucleophilic attack on the ethoxyphenoxycarbonium ion formed from the orthoformate by the organometallic anion, displacing two phenoxy groups to yield the α,α-disubstituted methyl ethers.
- Poncini, L.
-
p. 215 - 224
(2007/10/02)
-
- Ligand substitution kinetics of Mo(CO) (RC≡CR′) (S2CNMe2)2 complexes
-
Kinetics of the conversion of Mo(CO)(RC≡CR′)(S2CNMe2)2 to Mo(RC≡CR′)2(S2CNMe2)2 have been followed by visible spectroscopy. Both the reagents and products in this reaction are formally 16-electron complexes. The observed rate law is first order in metal complex and independent of free alkyne concentration when the reaction is run under an inert atmosphere. The reaction is inhibited in the presence of carbon monoxide gas, and the rate expression under 1 atm of carbon monoxide has a first-order dependence on alkyne. Reversible dissociation of carbon monoxide to generate a steady-state intermediate provides a simple mechanistic scheme which is compatible with the experimental results. The relative rate of carbon monoxide substitution corresponds qualitatively with the relative electron-withdrawing ability of the bound alkyne as reflected in the order PhC2Ph > PhC2H > PhC2Me > HC2-n-Bu > EtC2Et. When the free alkyne differs from the bound alkyne, a rapid alkyne-exchange reaction can be monitored for Mo(CO)(RC≡ CR′)(S2CNMe2)2 complexes by low-temperature 1H NMR spectroscopy. The second-order rate expression observed for alkyne exchange is consistent with an associative mechanism. Reactions of Mo(CO)(RC≡ CR′)(S2CNMe2)2 with nucleophiles (L = CO, P(OMe)3, PEt3) to form Mo(CO)L2(S2CNMe2)2 occur rapidly at room temperature. General features of associative and dissociative substitution mechanisms accessible to six-coordinate d4 Mo(CO)(RC≡CR′)(S2CNMe2)2 complexes are discussed in light of these results.
- Herrick, Richard S.,Leazer, D. Mark,Templeton, Joseph L.
-
p. 834 - 840
(2008/10/08)
-
- Stereochemistry of Olefin and Fatty Acid Oxidation. Part 1. Autooxidation of Hexene and Hepta-2,5-diene Isomers
-
The stereochemistry of the autooxidation of hex-1-ene, cis- and trans-hex-2-ene, cis- and trans-hex-3-ene, and of the three geometrical isomers of hepta-2,5-diene, has been determined by the reduction of the hydroperoxides produced and analysis of the resulting allylic alcohols.The relative proportions of the isomeric hydroperoxides are explicable in termes of the conformation of the parent olefins which are capable of giving delocalised radicals on hydrogen abstraction.
- Frankel, Edwin N.,Garwood, Robert F.,Vinson, John R.,Weedon, Basil C. L.
-
p. 2707 - 2714
(2007/10/02)
-
- A CONVENIENT ROUTE TO ALKYNES VIA PHASE TRANSFER CATALYSIS; ( APPLICATIONS OF PHASE TRANSFER CATALYSIS, PART 19 )
-
High yield, rapid formations of alkynes from vic-dibromides are possible using powered potassium hydroxide and catalytic amounts of lipophilic phase transfer catalysts.Reasons are given why molar amounts of expensive catalysts were necessary in earlier procedures.
- Dehmlow, Eckehard V.,Lissel, Manfred
-
p. 1653 - 1658
(2007/10/02)
-
- Reaction of α,β-Unsaturated Acid Chlorides with Tris(triphenylphosphine)chlororhodium(I): Formation of Phosphonium Salts
-
The reaction of (E)-cinnamoyl chloride and tris(triphenylphosphine)chlororhodium(I) in equivalent amounts in dichloroethane at 85 deg C gives styryltriphenylphosphonium chloride and bis(triphenylphosphine)chlorocarbonylrhodium in good yields. (E)-2-Butenoyl chloride gives 1-propenyltriphenylphosphonium chloride, and (E)-2-heptenoyl chloride gives a mixture of 1- and 2-hexenyltriphenylphosphonium chlorides. 3-Methyl-2-butenoyl chloride gives only isobutylene.None of these α,β-unsaturated acid chlorides give the expected 1-chloro-1-alkene.Control experiments showed that the phosphonium salts are not formed by secondary reactions.Bis(triphenylphosphine)styryldichlorocarbonylrhodium was shown to be an intermediate in the formation of styryltriphenylphosphonium chloride.A study of the kinetics of decomposition of the intermediate showed that dissociation of chloride ion is the rate-determining step.The observed rate law is -d/dt = kk'-> + k').The significance of these observations for an understanding of the details of the "reductive elimination" reaction is discussed.
- Kampmeier, J. A.,Harris, S. H.,Rodehorst, R. M.
-
p. 1478 - 1485
(2007/10/02)
-
- Application of Phase Transfer Catalysis, 14.- Preparation of Alkynes from Halides with Solid Potassium tert-Butoxide and Crown Ether
-
Preparatively very simple and mild HX eliminations with solid potassium tert-butoxide in petroleum ether in the presence of catalytic amounts of crown-6 are described. 1,2-Dihalides (from alkenes) and 1,1-dihalides (from aldehydes) yield 1-alkynes; internal geminal dihalides (from symmetric ketones) give internal alkynes in excellent yields. 2,2-Dihalides (from methyl ketones) yield homogeneous 1-alkynes only if the 3-position is blocked. (E)-Haloalkenes lead also to alkynes in a syn-elimination process.
- Dehmlow, Eckehard V.,Lissel, Manfred
-
-
- SYNTHESIS OF HIGHER ACETYLENIC ALCOHOLS
-
The alkylation of 1-alkynes in various solvents was investigated, and the optimum conditions for the production of acetylenic alcohols were obtained.
- Kovalev, B. G.,Matveeva, E. D.,Stan, V. V.,Vovk, G. A.,Yudin, L. G.,Kost, A. N.
-
p. 1728 - 1733
(2007/10/02)
-
- Hydroformylation of mono-α-olefins and mono-α-acetylenes
-
This invention relates to improvements in certain catalytic reactions, namely, hydrogenation, hydroformylation and carbonylation reactions.
- -
-
-
