- Synthesis of 2E,4E,6E,11Z-octadecatetraenoic acid of the Rhizobium leguminosarum biovar viciae Nod factor
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2E,4E,6E,11Z-Octadecatetraenoic acid was synthesized in a good yield and in a stereospecific manner by coupling a vinylborane compound and ethyl trans-3-iodoacrylate. The trienic system (E,E,E) was obtained by successive use of metal-catalyzed coupling and hydro-metallation reactions.
- Ghomsi, Joseph-Nathan Téné,Goureau, Olivine,Treilhou, Michel
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- Synthesis of (+)-crocacin D and simplified bioactive analogues
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The total synthesis of (+)-crocacin D has been achieved in 15 steps (9 isolated intermediates) and 14% overall yield from commercially available starting materials and using (+)-crocacin C as a key intermediate. A number of simplified analogues and their biological activities are also reported.
- Pasqua, Adele E.,Ferrari, Frank D.,Crawford, James J.,Whittingham, William G.,Marquez, Rodolfo
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- Substituent Effects in the Intramolecular Diels-Alder Reaction of 6-Furylhexenoates
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The series of furyl enone esters, 4a-c, were synthesized from furan or furfural by straightforward routes. Their thermal intramolecular Diels-Alder reactions to give the tricyclic ketones 5a-c were studied in acetonitrile and toluene at two temperatures and the kinetics of the reactions determined. A comparison of these data with that obtained for the corresponding esters 2 to give the lactones 3 indicates that the rate enhancements seen for the esters (rate of dimethyl 310 times that of monomethyl) are much larger than those seen for the ketones (rate of dimethyl 6.8 times that of monomethyl). Thus, this is additional evidence for the earlier hypothesis that the presence of the oxygen atom in the tether is a factor responsible for the larger than normal rate enhancements.
- Jung, Michael E.,Kiankarimi, Mehrak
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- Synthesis, radiolabeling, and preliminary in vivo evaluation of [68ga] ipcat-nota as an imaging agent for dopamine transporter
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Introduction: Novel radiotracer development for imaging dopamine transporters is a subject of interest because although [99mTc]TRODAT-1, [123I]β-CIT, and [123I]FP-CIT are commercially available;99Mo/99mTc generator is in short supply and123I production is highly dependent on compact cyclotron. Therefore, we designed a novel positron emission tomography (PET) tracer based on a tropane derivative through C-2 modification to conjugate NOTA for chelating68Ga, a radioisotope derived from a68Ge/68Ga generator. Methods: IPCAT-NOTA 22 was synthesized and labeled with [68Ga]GaCl4 ? at room tem-perature. Biological studies on serum stability, LogP, and in vitro autoradiography (binding assay and competitive assay) were performed. Furthermore, ex vivo autoradiography, biodis-tribution, and dynamic PET imaging studies were performed in Sprague Dawley rats. Results: [68Ga]IPCAT-NOTA 24 obtained had a radiochemical yield of ≥90% and a specific activity of 4.25 MBq/nmol. [68Ga]IPCAT-NOTA 24 of 85% radiochemical purity (RCP%) was stable at 37°C for up to 60 minutes in serum with a lipophilicity of 0.88. The specific binding ratio (SBR%) reached 15.8 ± 6.7 at 60 minutes, and the 85% specific uptake could be blocked through co-injection at 100-and 1000-fold of the cold precursor in in vitro binding studies. Tissue regional distribution studies in rats with [68Ga]IPCAT-NOTA 24 showed striatal uptake (0.02% at 5 minutes and 0.007% at 60 minutes) with SBR% of 6%, 25%, and 62% at 5–15, 30–40, and 60–70 minutes, respectively, in NanoPET studies. The RCP% of [68Ga]IPCAT-NOTA 24 at 30 minutes in vivo remained 67.65%. Conclusion: Data described here provide new information on the design of PET probe of conjugate/pendent approach for DAT imaging. Another chelator or another direct method of intracranial injection must be used to prove the relation between [68Ga]IPCAT-NOTA 24 uptake and transporter localization.
- Farn, Shiou-Shiow,Chang, Kang-Wei,Lin, Wan-Chi,Yu, Hung-Man,Lin, Kun-Liang,Tseng, Yu-Chin,Chang, Yu,Yu, Chung-Shan,Lin, Wuu-Jyh
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p. 2577 - 2591
(2021/07/06)
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- Preparation method of selinexor and intermediate thereof
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The invention relates to a preparation method of selinexor and an intermediate thereof, which has the advantages of short synthetic route, mild reaction conditions, no foul gas generation in the reaction process, high safety, wide acceptable range of vari
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Paragraph 0155-0158
(2021/04/21)
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- Diastereo- and Enantioselective Cross-Couplings of Secondary Alkylcopper Reagents with 3-Halogeno-Unsaturated Carbonyl Derivatives
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Chiral secondary alkylcopper reagents were prepared from the corresponding alkyl iodides with retention of configuration by an I/Li-exchange using tBuLi (?100 °C, 1 min) followed by a transmetalation with CuBr?P(OEt)3 (?100 °C, 20 s). These ste
- Kremsmair, Alexander,Skotnitzki, Juri,Knochel, Paul
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supporting information
p. 11971 - 11973
(2020/09/07)
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- Total synthesis of selaginpulvilins A and C
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An efficient formal total synthesis of two compounds from the selaginpulvilin family of natural products, selaginpulvilin A and C, has been successfully achieved. The tetradehydro Diels-Alder (TDDA) reaction between an enyne and alkyne has been utilized for the creation of the necessary fluorene skeleton. Attempts at the conversion of selaginpulvilin A to selaginpulvilin B, F and H were unsuccessful.
- Chinta, Bhavani Shankar,Baire, Beeraiah
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supporting information
p. 262 - 265
(2018/01/12)
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- Palladium-catalyzed convenient one-pot synthesis of multi-substituted 2-pyrones via transesterification and alkenylation of enynoates
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An efficient one-pot protocol for the synthesis of multi-substituted 2-pyrone derivatives from internal alkynes and unactivated alkenes is reported. The methodology involves difunctionalization of internal alkynes by using Pd(II) as a catalyst alongwith X-Phos as ligand via 6-endo transesterification and subsequent alkenylation pathway. Notable features include simple and easily available starting materials, including a range of unactivated alkenes, reduced synthetic steps and mild reaction conditions with high efficiency.
- Pathare, Ramdas S.,Sharma, Shivani,Gopal, Kandasamy,Sawant, Devesh M.,Pardasani, Ram T.
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supporting information
p. 1387 - 1389
(2017/03/17)
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- Intramolecular cascade rearrangements of enynamine derived ketenimines: Access to acyclic and cyclic amidines
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Copper-catalyzed reaction of enynamines with sulfonylazides provides acyclic and cyclic amidines. Nucleophilic addition of the tethered amino group on the in situ generated ketenimine forms a six-membered cyclic zwitterionic intermediate which facilitates
- Chauhan, Dinesh Pratapsinh,Varma, Sreejith J.,Gudem, Mahesh,Panigrahi, Nihar,Singh, Khushboo,Hazra, Anirban,Talukdar, Pinaki
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supporting information
p. 4822 - 4830
(2017/07/10)
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- Catalyst-Free Synthesis of Borylated Lactones from Esters via Electrophilic Oxyboration
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A catalyst-free oxyboration reaction of alkynes is developed. The resulting borylated isocoumarins and 2-pyrones are isolated as boronic acids, pinacolboronate esters, or potassium organotrifluoroborate salts, providing a variety of bench-stable organobor
- Faizi, Darius J.,Issaian, Adena,Davis, Ashlee J.,Blum, Suzanne A.
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supporting information
p. 2126 - 2129
(2016/03/05)
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- Tetra-substituted pyridinylimidazoles as dual inhibitors of p38α mitogen-activated protein kinase and c-jun N-terminal kinase 3 for potential treatment of neurodegenerative diseases
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Tetra-substituted imidazoles were designed as dual inhibitors of c-Jun N-terminal kinase (JNK) 3 and p38α mitogen-activated protein (MAP) kinase. A library of 45 derivatives was prepared and evaluated in a kinase activity assay for their ability to inhibi
- Muth, Felix,Günther, Marcel,Bauer, Silke M.,D?ring, Eva,Fischer, Sabine,Maier, Julia,Drückes, Peter,K?ppler, Jürgen,Trappe, J?rg,Rothbauer, Ulrich,Koch, Pierre,Laufer, Stefan A.
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supporting information
p. 443 - 456
(2015/07/27)
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- Practical methods for the synthesis of trifluoromethylated alkynes: Oxidative trifluoromethylation of copper acetylides and alkynes
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Two practical and complementary methods are reported for the synthesis of trifluoromethylated alkynes. The first one, a mix-and-stir process, is based on the oxidative trifluoromethylation of readily available and bench-stable copper acetylides while the second one, which displays a broad substrate scope and has several advantages over existing procedures, is based on the oxidative copper-catalyzed direct trifluoromethylation of terminal alkynes. Both reactions provide user-friendly processes for the synthesis of trifluoromethylated acetylenes which can be easily obtained from readily available starting materials.
- Tresse, Cedric,Guissart, Celine,Schweizer, Stephane,Bouhoute, Yassine,Chany, Anne-Caroline,Goddard, Mary-Lorene,Blanchard, Nicolas,Evano, Gwilherm
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supporting information
p. 2051 - 2060
(2014/07/07)
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- Gold(III)-catalyzed intramolecular furanylation and cyclopropanation of acyclic conjugated enynones
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We have developed an efficient cascade gold-catalyzed furanylation- cyclopropanation of acyclic (E)-deca-2,9-dien-4-yn-1-ones and an (E)-undeca-2,10-dien-4-yn-1-one to give 1-(2-furyl)bicyclo[3.1.0]hexanes and a 1-(2-furyl)bicyclo[4.1.0]heptane, respectiv
- Oh, Chang Ho,Piao, Lanhua,Kim, Ji Hee
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p. 174 - 182
(2013/02/23)
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- A convergent approach to (-)-callystatin a based on local symmetry
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The key is symmetry! A convergent synthetic approach of the highly cytotoxic natural product (-)-callystatin A was developed assembling three fragments through Julia-Kocienski olefination and Stille cross-coupling. The new strategy relies on a pivotal local symmetry of the target molecule. In this preliminary study, particular attention was devoted to facilitate the catalytic enantiocontrol of strategic stereogenic centers present in each of the fragments (see scheme). Copyright
- Candy, Mathieu,Tomas, Lo?c,Parat, Sabrina,Heran, Virginie,Bienaymé, Hugues,Pons, Jean-Marc,Bressy, Cyril
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supporting information
p. 14267 - 14271
(2013/01/15)
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- Total synthesis of branimycin: An evolutionary approach
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The first total synthesis of the macrolactone antibiotic branimycin (4) has been described. The key disconnection leads to a cis-dehydrodecalone core and a polyketide side chain which are connected via organometallic addition. The dehydrodecalone core was targeted via altogether five different approaches featuring various kinds of chiral elements and ring-closing methodology. In the end the most successful method starting from diepoxynaphthalene 109 was chosen to carry on with the synthesis. Thus the oxygen functions and carbon appendages were introduced via organometallic desymmetrization reactions to generate epoxy ketone 107, to which vinyl iodide 11 was added after conversion into the organolithium species. The synthesis was completed by introducing the ester side chain via Michael addition and subsequent macrolactonization. Competitive approach: The first total synthesis of the macrolactone antibiotic branimycin is described (see figure). The dehydrodecalin core was targeted via five competing approaches featuring various kinds of chiral elements and ring-closing methodology. In this "Darwinian" struggle the most successful route emerged and led to the completion of the synthesis. Copyright
- Enev, Valentin S.,Felzmann, Wolfgang,Gromov, Alexey,Marchart, Stefan,Mulzer, Johann
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supporting information; experimental part
p. 9651 - 9668
(2012/09/21)
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- Synthesis and properties of seleno-analog MK-organic dye for photovoltaic cells prepared by CH functionalization reactions of selenophene derivatives
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C-H arylation and homocoupling reactions of 2-formylselenophene were carried out with a palladium catalyst. By using these coupling reactions a seleno-analog of MK dye MK-49, which is an organic dye molecule of a dye-sensitized solar cell (DSSC), was synt
- Tamba, Shunsuke,Fujii, Ryosuke,Mori, Atsunori,Hara, Kohjiro,Koumura, Nagatoshi
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supporting information; experimental part
p. 978 - 979
(2012/01/30)
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- The vinyl moiety as a handle for regiocontrol in the preparation of unsymmetrical 2,3-aliphatic-substituted indoles and pyrroles
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Rho-Rho-Rho your boat: A rhodium catalyst effects the regioselective oxidative coupling of enynes with N-aryl ureas (X=NR2) and N-vinylacetamides (X=C(O)Me), affording the corresponding 2-alkenylindoles and 2-alkenylpyrroles in good yield. Simple hydrogenation delivers the C2/C3-aliphatic-substituted indole or pyrrole (see scheme).
- Huestis, Malcolm P.,Chan, Lina,Stuart, David R.,Fagnou, Keith
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supporting information; scheme or table
p. 1338 - 1341
(2011/04/21)
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- Highly selective synthesis of conjugated dienoic and trienoic esters via alkyne elementometalation - Pd-catalyzed cross-coupling
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All four stereoisomers (7-10) of ethyl undeca-2,4-dienoate were prepared in ≥98% isomeric purity by Pd-catalyzed alkenylation (Negishi coupling) using ethyl (E)- and (Z)-β-bromoacrylates. Although the stereoisomeric purity of the 2Z,4E-isomer (8) prepared by Suzuki coupling using conventional alkoxide and carbonate bases was ≤95%, as reported earlier, the use of CsF or nBu4NF as a promoter base has now been found to give all of 7-10 in ≥98% selectivity. Other widely known methods reveal considerable limitations. Heck alkenylation was satisfactory for the syntheses of the 2E,4E and 2E,4Z isomers of ≥98% purity, but the purity of the 2Z,4E isomer was ≤95%. Mutually complementary Horner-Wadsworth-Emmons and Still-Gennari (SG) olefinations are also of considerably limited scopes. Neither 2E,4Z nor 2Z,4Z isomer is readily prepared in ≥90% selectivity. In addition to (2Z,4E)-dienoic esters, some (2Z,4E,6E)- and (2Z,4E,6Z)-trienoic esters have been prepared in ≥98% selectivity by a newly devised Pd-catalyzed alkenylation-SG olefination tandem process. As models for conjugated higher oligoenoic esters, all eight stereoisomers for ethyl trideca-2,4,6-trienoate (23-30) have been prepared in ≥98% overall selectivity.
- Wang, Guangwei,Mohan, Swathi,Negishi, Ei-Ichi
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scheme or table
p. 11344 - 11349
(2011/10/30)
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- Total synthesis and configurational validation of (+)-phorbaside A
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Figure presented The configurational assignment of the cytotoxic marine macrolide phorbaside A has been verified by the stereodefined synthesis of the proposed structure 1 and its (18S,19R)-diastereomer 3, followed by correlation using circular dichroism spectroscopy. This first total synthesis, which proceeds in 8.2% yield over 23 steps, features two 1,4-syn boron aldol reactions, a Sonogashira coupling, and an α-glycosylation to append the l-evalose sugar moiety.
- Paterson, Ian,Paquet, Tanya
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supporting information; experimental part
p. 2158 - 2161
(2010/08/06)
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- Stereoselective total synthesis of etnangien and etnangien methyl ester
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A highly stereoselective joint total synthesis of the potent polyketide macrolide antibiotics etnangien and etnangien methyl ester was accomplished by a convergent strategy and proceeds in 23 steps (longest linear sequence). Notable synthetic features include a sequence of highly stereoselective substrate-controlled aldol reactions to set the characteristic assembly of methyl- and hydroxyl-bearing stereogenic centers of the propionate portions, an efficient diastereoselective Heck macrocyclization of a deliberately conformationally biased precursor, and a late-stage introduction of the labile side chain by means of a high-yielding Stille coupling of protective-group-free precursors. Along the way, an improved, reliable protocol for a Z-selective Stork?Zhao?Wittig olefination of aldehydes was developed, and an effective protocol for a 1,3-syn reduction of sterically particularly hindered β-hydroxy ketones was devised. Within the synthetic campaign, a more detailed understanding of the intrinsic isomerization pathways of these labile natural products was elaborated. The expedient and flexible strategy of the etnangiens should be amenable to designed analogues of these RNA-polymerase inhibitors, thus enabling further exploration of the promising biological potential of these macrolide antibiotics.
- Li, Pengfei,Li, Jun,Arikan, Fatih,Ahlbrecht, Wiebke,Dieckmann, Michael,Menche, Dirk
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supporting information; experimental part
p. 2429 - 2444
(2010/07/06)
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- Total syntheses of (±)-ovalicin, C4(S*)-isomer, and its C5-analogs and anti-trypanosomal activities
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Total syntheses of (±)-ovalicin, its C4(S*)-isomer 44, and C5-side chain intermediate 46 were accomplished via an intramolecular Heck reaction of (Z)-3-(tert-butyldimethylsilyloxy)-1-iodo-1,6-heptadiene and a catalytic amount of palladium aceta
- Hua, Duy H.,Zhao, Huiping,Battina, Srinivas K.,Lou, Kaiyan,Jimenez, Ana L.,Desper, John,Perchellet, Elisabeth M.,Perchellet, Jean-Pierre H.,Chiang, Peter K.
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p. 5232 - 5246
(2008/12/21)
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- Stereoselective hydrohalogenation of alkynoic acids and their esters in ionic liquids
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A novel procedure is described for the hydrohalogenation of alkynoic acids and their esters using N-alkylpyridinium ionic liquids. Hydrohalogenating agents were prepared by mixing N-alkylpyridinium halides with an equimolar amount of trifluoroacetic acid.
- Salazar, Jose,Fernandez, Francys,Restrepo, Jelem,Lopez, Simon E.
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p. 170 - 172
(2008/02/12)
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- Applying asymmetric dihydroxylation to the synthesis of difluorinated carbohydrate analogues: A 1,1-difluoro-1-deoxy-d-xylulose
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Readily available difluoroenol iodides and stannanes undergo palladium-catalysed coupling reactions with alkenylstannanes and iodides, respectively, to afford a trial set of difluorinated 1,3- and 1,4-dienes, which were then exposed to AD conditions. A nu
- Cox, Liam R.,Deboos, Gareth A.,Fullbrook, Jeremy J.,Percy, Jonathan M.,Spencer, Neil
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p. 347 - 359
(2007/10/03)
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- Ru-catalyzed alkene-alkyne coupling. Total synthesis of amphidinolide P
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A coordinatively unsaturated ruthenium complex catalyzed the formation of a carbon-carbon bond between two judiciously chosen alkene and alkyne partners in good yield, and in a chemo- and regioselective fashion, despite the significant degree of unsaturation of the substrates. The resulting 1,4-diene forms the backbone of the cytotoxic marine natural product amphidinolide P. The alkene partner was rapidly assembled from (R)-glycidyl tosylate, which served as a linchpin in a one-flask, sequential three-components coupling process using vinyllithium and a vinyl cyanocuprate. The synthesis of the alkyne partner made use of an unusual anti-selective addition under chelation-control conditions of an allyltin reagent derived from tiglic acid. In addition, a remarkably E-selective E2 process using the azodicarboxylate-triphenylphosphine system is featured. Also featured is the first example of the use of a β-lactone as a thermodynamic spring to effect macrolactonization. The oxetanone ring was thus used as a productive protecting group that increased the overall efficiency of this total synthesis. This work was also an opportunity to further probe the scope of the ruthenium-catalyzed alkene-alkyne coupling, in particular using enynes, and studies using various functionalized substrates are described.
- Trost, Barry M.,Papillon, Julien P. N.,Nussbaumer, Thomas
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p. 17921 - 17937
(2007/10/03)
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- Reactivity and Enantioselectivity in the Reactions of Scalemic Stereogenic α-(N-Carbamoyl)alkylcuprates
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Stereogenic 2-(N-carbamoyl)pyrrolidinylcuprates prepared from scalemic (i.e., enantioenriched) N-Boc-2-lithiopyrrolidine and THF soluble CuCN·2LiCl react with vinyl iodides, vinyl triflates, β-iodo-α,β-enoates, propargyl mesylates, and allyl bromide to afford the substitution products with excellent enantioselectivity. Excellent enantiomeric ratios are obtained in the conjugate addition reactions with methyl vinyl ketone while low enantiomeric ratios can be achieved with acrylate esters using HMPA/TMSCl activation. Enantiomeric ratios vary with substrate substitution patterns and the observed enantioselectivities appear to be more a function of cuprate-electrophile reactivities than of the reaction type (e.g., substitution, conjugate addition). Low enantiomeric ratios are obtained with the α-(N-carbamoyl)benzylcuprates. The lithium-copper transmetalation and cuprate vinylation reactions proceed with retention of configuration.
- Dieter, R. Karl,Oba, Gabriel,Chandupatla, Kishan R.,Topping, Chris M.,Lu, Kai,Watson, Rhett T.
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p. 3076 - 3086
(2007/10/03)
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- Catalytic asymmetric synthesis of a 1-deoxy-1,1-difluoro-D-xylulose.
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[reaction: see text] A new route, of potential strategic importance, to a difluorosugar analogue has been developed. Key steps included a Stille coupling and a highly regio- and enantioselective dihydroxylation of a highly substituted diene. Protecting gr
- Cox, Liam R,DeBoos, Gareth A,Fullbrook, Jeremy J,Percy, Jonathan M,Spencer, Neil S,Tolley, Malcolm
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p. 337 - 339
(2007/10/03)
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- Synthesis of pyrroles through coupling of enyne-hydrazones with fischer carbene complexes
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Matrix presented The coupling of enyne-imines with Fischer carbene complexes leads to the formation of alkenylpyrrole derivatives. Maximum yields of pyrrole adducts were obtained using N,N-dimethylhydrazones. A mechanism involving alkyne insertion followe
- Zhang, Yanshi,Herndon, James W.
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p. 2043 - 2045
(2007/10/03)
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- A simple and versatile method for the hydroiodination of alkenes and alkynes using I2 and Et3SiH in the presence of copper(II)
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The reagent system CuO·HBF4/I2/Et3SiH generates in situ hydrogen iodide which regioselectively adds to alkenes and alkynes. The mild nature of this system tolerates the presence of different groups on the unsaturated compound.
- Campos, Pedro J.,García, Bárbara,Rodríguez, Miguel A.
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p. 6111 - 6112
(2007/10/03)
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- α-(N-carbamoyl)alkylcuprate chemistry in the synthesis of nitrogen heterocycles
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The conjugate adducts obtained via coupling of α-(N-carbamoyl)alkylcuprates with α,β-ynoates, α-allenyl esters, or α,β-enoates or enimides undergo N-Boc deprotection and cyclization onto the ester functionality upon treatment with PhOH/TMSCl, catecholboron bromide, or trimethylsilyl triflate. This two-pot sequence provides synthetic routes to 4-alkylidinepyrrolidine-2-ones, 4-alkylidinepyrrolizidin-2-ones, and 4-alkylidineindolizidin-2-ones via allenyl esters; pyrrolin-2-ones, tetrahydropyrrolizin-2-ones, and tetrahydroindolizin-2-ones via α,β-ynoates; pyrrolidin-2-ones, pyrrolizidin-2-ones, and indolizidin-2-ones via α,β-enoates or α,β-enimides. The reluctance of γ-carbamoyl-α,β-enoates to undergo E/Z isomerization requires the use of (Z)-β-iodo-α,β-enoates readily prepared by the addition of HI to the alkynyl esters for the efficient preparation of pyrrolinones, tetrahydropyrrolizinones, and tetrahydroindolizinones. Utilization of ω-functionalized α,β-ynoates or β-iodo-α,β-enoates allows for cyclization onto the ω-functionality providing for a synthetic route to quinolizidines.
- Dieter, R. Karl,Lu, Kai
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p. 847 - 855
(2007/10/03)
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- Stereodefined Substituted Cyclopropyl Zinc Reagents from Gem-Bismetallics
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1,1- or n,n-Bismetallic reagents bearing a methoxymethyl ether in the γ position undergo cyclization at room temperature to give monometalated, diastereoselectively substituted cyclopropanes.The nature of the substituents is crucial for this diastereoselection, a ?-chelation between one metal and a properly located unsaturation, as well as 1,2-strain, are proposed to explain the steric outcome of these reactions.
- Beruben, Dov,Marek, Ilane,Normant, Jean F.,Platzer, Nicole
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p. 2488 - 2501
(2007/10/02)
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- A convenient procedure for the efficient preparation of alkyl (Z)-3-iodo-2-alkenoates
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Reaction of alkyl 2-alkynoates with sodium iodide (1.6-5.5 equiv.) in acetic acid (6.2-13 equiv.) at 115 deg C provides good to excellent yields of the corresponding alkyl (Z)-3-iodo-2-alkenoates.
- Piers, Edward,Wong, Timothy,Coish, Philip D.,Rogers, Christine
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p. 1816 - 1819
(2007/10/02)
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- A Novel Regio- and Stereospecific Hydrohalogenation Reaction of 2-Propynoic Acid and Its Derivatives
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2-Propynoic acid and its derivatives are hydrohalogenated regio- and stereospecifically by reaction with lithium halides in acetic acid, or preferably with 1 equiv of acetic acid in refluxing CH3CN, to afford the thermodynamically unfavorable (Z)-3-halopropenoic acids and their derivatives as sole products.A rationale for the regio- and stereospecifity is briefly discussed.
- Ma, Shengming,Lu, Xiyan,Li, Zhigang
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p. 709 - 713
(2007/10/02)
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- A Novel Stereospecific Hydrohalogenation Reaction of Propiolates and Propiolic Acid
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(Z)-3-Halo-propenoates or -propenoic acids have been synthesized stereospecifically by the reaction of lithium halides in acetic acid with propiolates or propiolic acid, respectively.
- Ma, Shengming,Lu, Xiyan
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p. 1643 - 1644
(2007/10/02)
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- STEREOCONTROLLED SYNTHESIS OF NATURALLY-OCCURRING POLYACETYLENES CHARACTERIZED BY (E)-1-EN-3-YNE, (E)-1-EN-3,5-DIYNE, (1E,5E)-1,5-DIEN-3-YNE, AND (1E,7E)-1,7-DIEN-3,5-DIYNE MOIETIES
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A stereocontrolled synthesis of five naturally-occurring polyacetylenes, i.e. methyl (E)-5-(2-thienyl)-2-penten-4-ynoate, 9, (E)-N-methyl-N-(2-methylpropyl)-2-decen-4,6-diynamide, 10, (E)-1-(3-methyl-2-butenoyloxy)-2-decen-4,6-diyne, 11, (2E,6E)-1-acetoxy-2,6-decadien-4-yne, 12, and (2E,8E)-1-acetoxy-2,8-decadien-4,6-diyne, 13, is reported.The flexible strategy involves palladium(0)-copper(I) catalyzed coupling reactions to construct the carbon skeleton of the target molecules and to prepare an important C5 building block, i.e. (E)-2-penten-4-yn-1-ol, 21.This compound is also an useful intermediate to lipoxins A and B.A highly diastereoselective palladium-catalyzed carbon-carbon bond forming reaction, recently developed in our laboratory, has been used in a key synthetic step to compound 12.
- Carpita, Adriano,Neri, Dario,Rossi, Renzo
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p. 481 - 490
(2007/10/02)
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