- Degenerative xanthate transfer to olefins under visible-light photocatalysis
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The degenerative transfer of xanthates to olefins is enabled by the iridium-based photocatalyst [Ir{dF(CF3)ppy}2(dtbbpy)](PF6) under blue LED light irradiation. Detailed mechanistic investigations through kinetics and phot
- Kaga, Atsushi,Wu, Xiangyang,Yi, Joel,Lim, Jie,Hayashi, Hirohito,Lu, Yunpeng,Yeow, Edwin K.L.,Chiba, Shunsuke
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- Oxidative Hydro-, Bromo-, and Chloroheptafluoroisopropylation of Unactivated Alkenes with Heptafluoroisopropyl Silver
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Oxidant-induced three-component hydro-, bromo-, and chloroheptafluoroisopropylation of unactivated alkenes are disclosed. In these reactions, the CF(CF3)2 radical was generated from the oxidation of AgCF(CF3)2.
- Tong, Chao-Lai,Xu, Xiu-Hua,Qing, Feng-Ling
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- Synthesis, characterization and conducting properties of sulfonated poly and co-polymer of cholesteryl 4-pentenoate with 1-hexene
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This manuscript reports the synthesis of the liquid crystalline (LC) monomer cholesteryl 4-pentenoate and its sulfone and co-polysulfone with 1-hexene. The polymers were characterized by IR, 1H-NMR, differential scanning calorimetry and thermogravimetric analysis techniques. The LC phases were observed under a hot stage fitted with a polarizing optical microscope. The elemental analysis for the sulfone group was done by SEM (energy dispersive X-ray analysis) analysis. The amount of elemental sulfur present in polysulfone and co-polysulfone is 4.95 weight (%) and 5.71weight (%), respectively. The molecular weights were determined by Gel Permeation Chromatography, using tetrahydrofuran as the solvent. The number average molecular weight of the polysulfone is 5950 g/mol. The molecular weights of the co-polysulfones were found to be higher than the polysulfone. From I-V characteristics, the breaking voltage for the polymers was computed to be around 5 V. The conductivity of the polysulfone and co-polysulfones increases with increasing temperature.
- Hoque, Samiul,Dass, Narendra Nath,Bhattcharyya, Krishna Gopal,Sarma, Neelotpal Sen
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- A short and efficient synthesis of bridgehead mono-and dideuteriated tropinones
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Studies of the biosynthesis and degradation of alkaloids of the tropane class require substrates isotopically-labelled at specific positions. To investigate the mechanism of the enzyme reactions involved in the hydroxylation of the bridgehead position(s), compounds deuteriated at this position are needed. An efficient synthesis of 1,5-dideuterio-and racemic 1-deuteriotropinone is described in which high levels of deuterium are incorporated from the corresponding di-and mono-labelled 2,5-dibutoxytetrahydrofuran.
- Fournial, Anais,Ranaivondrambola, Tsiresy,Mathe-Allainmat, Monique,Robins, Richard J.,Lebreton, Jacques
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- Total synthesis of phenanthroindolizidine alkaloids through an amidyl radical cascade/rearrangement reaction
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A short and general synthesis of the phenanthroindolizidine alkaloids is reported, featuring an unusual amidyl radical 5-exo/5-exo/rearrangement cascade of a xanthate precursor. Second, using an amidyl radical 5-exo/6-endo cascade to synthesize a phenanth
- Han, Guifang,Liu, Yuxiu,Wang, Qingmin
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- Synthesis and recognition properties of polymers containing embedded binding sites
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We report the synthesis and guest affinities of polymers featuring a single recognition site in the middle of the polymer chain. These polymers were synthesized from difunctional initiators based on the 2,6-diacyldiaminopyridine moiety. Binding efficiencies were experimentally determined using a complementary fluorescent guest, N(10)-isopropyl flavin. The effect of polymer length on recognition was explored by the synthesis of 5 PMMA samples ranging from 4K to 25K. Over this range binding constants increased almost 2-fold, from 282 to 522 M-1. Variable temperature fluorescence of bound samples shows a 15% difference in release between polymer samples and model compounds.
- Das, Kanad,Nakade, Hiroshi,Penelle, Jacques,Rotello, Vincent M.
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- Synthesis and Biological Evaluation of Endocannabinoid Uptake Inhibitors Derived from WOBE437
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WOBE437 ((2E,4E)-N-(3,4-dimethoxyphenethyl)dodeca-2,4-dienamide, 1) is a natural product-derived, highly potent inhibitor of endocannabinoid reuptake. In this study, we synthesized almost 80 analogues of 1 with different types of modifications in the dodecadienoyl domain as well as the dimethoxyphenylethyl head group, and we investigated their effects on anandamide uptake into U937 cells. Intriguingly, none of these analogues was a more potent inhibitor of anandamide uptake than WOBE437 (1). At the same time, a number of WOBE437 variants exhibited potencies in the sub-100 nM range, with high selectivity over inhibition of the endocannabinoid-degrading enzyme fatty acid amide hydrolase; two compounds were virtually equipotent with 1. Interestingly, profound activity differences were observed between analogues in which either of the two methoxy substituents in the head group had been replaced by the same bulkier alkoxy group. Some of the compounds described here could be interesting departure points for the development of potent endocannabinoid uptake inhibitors with more drug-like properties.
- M?der, Patrick,Bartholom?us, Ruben,Nicolussi, Simon,Baumann, Alice,Weis, Melanie,Chicca, Andrea,Rau, Mark,Sim?o, Ana Catarina,Gertsch, Jürg,Altmann, Karl-Heinz
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supporting information
p. 145 - 154
(2020/06/02)
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- Direct and Enantioselective Aldol Reactions Catalyzed by Chiral Nickel(II) Complexes
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A direct and asymmetric aldol reaction of N-acyl thiazinanethiones with aromatic aldehydes catalyzed by chiral nickel(II) complexes is reported. The reaction gives the corresponding O-TIPS-protected anti-aldol adducts in high yields and with remarkable stereocontrol and atom economy. Furthermore, the straightforward removal of the achiral scaffold provides enantiomerically pure intermediates of synthetic interest, which involve precursors for anti-α-amino-β-hydroxy and α,β-dihydroxy carboxylic derivatives. Theoretical calculations explain the observed high stereocontrol.
- Kennington, Stuart C. D.,Teloxa, Saul F.,Mellado-Hidalgo, Miguel,Galeote, Oriol,Puddu, Sabrina,Bellido, Marina,Romea, Pedro,Urpí, Fèlix,Aullón, Gabriel,Font-Bardia, Mercè
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supporting information
p. 15307 - 15312
(2021/06/11)
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- Electrodimerization ofN-Alkoxyamides for the Synthesis of Hydrazines
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An efficient and valuable N-N dimerization reaction ofN-alkoxyamides is reported under undivided electrolytic conditions. This electrochemical strategy provides a powerful way to access a wide range of advanced, highly functionalized hydrazines. Remarkably, anN-centered radical generated from the cleavage of the N-H bond under electrolytic conditions plays a crucial role in this transformation. Furthermore, variousN-alkoxyamides bearing different substituents are suitable in this transformation, furnishing the corresponding hydrazines in up to 92% yield.
- Nasier, Abudulajiang,Chang, Xihao,Guo, Chang
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p. 16068 - 16076
(2021/09/18)
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- Decarboxylative Borylation of mCPBA-Activated Aliphatic Acids
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A decarboxylative borylation of aliphatic acids for the synthesis of a variety of alkylboronates has been developed by mixing m-chloroperoxybenzoic acid (mCPBA)-activated fatty acids with bis(catecholato)diboron in N,N-dimethylformamide (DMF) at room temperature. A radical chain process is involved in the reaction which initiates from the B-B bond homolysis followed by the radical transfer from the boron atom to the carbon atom with subsequent decarboxylation and borylation.
- Wei, Dian,Liu, Tu-Ming,Zhou, Bo,Han, Bing
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supporting information
p. 234 - 238
(2020/01/02)
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- Redox-Neutral Nickel(II) Catalysis: Hydroarylation of Unactivated Alkenes with Arylboronic Acids
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Reported here is the discovery of a redox-neutral NiII/NiII catalytic cycle which is capable of the linear-selective hydroarylation of unactivated alkenes with arylboronic acids for the first time. This novel catalytic cycle, enabled
- Feng, Wang,Liu, Tao,Wang, Dao-Ming,Wang, Peng,Wu, Yichen
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supporting information
p. 20399 - 20404
(2020/09/09)
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- Development of an Efficient Synthesis of rac-3-Demethoxyerythratidinone via a Titanium(III) Catalyzed Imine-Nitrile Coupling
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We herein describe the evolution of a rapid, high-yielding synthesis of the erythrina alkaloid 3-demethoxyerythratidinone. The natural product is assembled in six steps from commercial precursors in 30–35 % overall yield and with only two chromatographical purification operations. The key step is a titanium(III) catalyzed umpolung reaction in form of a reductive imine–nitrile coupling that can be combined with a subsequent cyclization reaction on a 50 mmol scale. Furthermore, optimized Wacker oxidation conditions enable the selective alkene oxidation in the presence of a tertiary amine functionality, which has been a problem in previous syntheses of erythrina alkaloids. The racemic route can be used to prepare the natural product on gram scale and the results may be useful for the synthesis of related alkaloids.
- Luu, Hieu-Trinh,Streuff, Jan
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p. 139 - 149
(2019/01/04)
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- Isoalantolactone derivative, pharmaceutical composition and application thereof
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The invention relates to an isoalantolactone derivative, a pharmaceutical composition and application thereof, especially use of the isoalantolactone derivative shown as formula (I) or a salt pharmaceutical compound thereof in preparation of adjuvant drugs treating cancer, a pharmaceutical composition containing a therapeutically effective amount of isoalantolactone derivative (I) or its salt anda pharmaceutically acceptable carrier or a composition with other anticancer drugs.
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Paragraph 0014
(2019/02/02)
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- Synthesis of Ynolates via Double Deprotonation of Nonbrominated Esters
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Herein, we report a double deprotonation method used for the preparation of ynolates starting from nonbrominated 2,6-di-tert-butylphenyl esters. The current method is superior to the previously described double lithium/halogen exchange approach because easily accessible starting materials are used. This method will be especially useful for preparation of ynolates bearing functional groups in organic synthesis.
- Sun, Jun,Yoshiiwa, Toshiya,Iwata, Takayuki,Shindo, Mitsuru
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supporting information
p. 6585 - 6588
(2019/09/30)
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- Regiodivergent Iridium(III)-Catalyzed Diamination of Alkenyl Amides with Secondary Amines: Complementary Access to γ- Or δ-Lactams
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Alkenyl N-pivaloylhydroxamates undergo an Ir(III)-catalyzed diamination of the alkene with simple exogenous secondary amines under extraordinarily mild reaction conditions. The regioselectivity of the diamination is controlled by the solvent and the electronics of the cyclopentadienyl (Cpx) ligand on Ir. On the basis of a set of mechanistic experiments, we propose that the relative rates of Ir(V)-nitrenoid formation versus attack on the amido-Ir-coordinated alkene by the exogenous amine determine the outcome of the reaction.
- Conway, John H.,Rovis, Tomislav
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supporting information
p. 135 - 138
(2018/01/17)
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- Diastereoselective Electrophilic Trifluoromethylthiolation of Chiral Oxazolidinones: Access to Enantiopure α-SCF3 Alcohols
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Lithium imide enolates featuring Evans’ chiral oxazolidinone auxiliary were involved in diastereoselective α-trifluoromethylthiolation with electrophilic SCF3 donors. Diastereopure products were isolated and converted to enantiopure α-SCF3 alcohols without racemisation. (Figure presented.).
- Chachignon, Hélène,Kondrashov, Evgeniy V.,Cahard, Dominique
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supporting information
p. 965 - 971
(2018/01/27)
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- Total Synthesis of Belizentrin Methyl Ester: Report on a Likely Conquest
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The assigned structure of the dinoflagellate-derived toxin belizentrin was prepared by total synthesis in form of the corresponding methyl ester for stability reasons. The successful route features an unusual solution for the preparation of a recalcitrant ylide on a C-glycosidic segment; moreover, it involves an asymmetric hetero-Diels–Alder reaction en route to the tertiary hemiacetal substructure, a Negishi cross-coupling of two elaborate building blocks, and a macrocyclization based on an intramolecular aminolysis of a spirolactone. A modified Kocienski olefination ultimately allowed the polyol side chain to be attached to the macrocycle although this transformation faced the exceptional base sensitivity of this polyunsaturated target compound.
- Anderl, Felix,Gr??l, Sylvester,Wirtz, Conny,Fürstner, Alois
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supporting information
p. 10712 - 10717
(2018/08/17)
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- Preliminary investigations into the synthesis and antimicrobial activities of boron-containing capsaicinoids
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This preliminary study reports on the synthesis of two new boron-capsaicin derivatives containing either a short or long chain aliphatic tail group using an iridium catalyzed hydroboration reaction with pinacolborane. The boronate ester groups reside on the terminal position of the tail group and are necessary for the bioactivity of these compounds. Indeed, both compounds showed considerable activity against two Gram-positive bacteria, including Vancomycin-resistant Enterococcus. Vancomycin is considered the last resort medication for the treatment of septicemia, and new antibacterial agents that can treat sepsis are of paramount importance. The more lipophilic boron compound with the longer aliphatic chain also showed antifungal activity against Saccharomyces cerevisiae.
- Ramsaywack, Sharwatie,Bos, Allyson,Vogels, Christopher M.,Gray, Christopher A.,Westcott, Stephen A.
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supporting information
p. 1065 - 1070
(2018/11/24)
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- Synthetic studies toward isoschizogamine: Construction of pentacyclic core structure
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Development of a concise construction of the pentacyclic core skeleton of isoschizogamine was described. Tetracyclic A,B,D,F-rings structure was assembled by intramolecular aza-Diels–Alder reaction via an ortho-iminoquinone methide intermediate. The C-ring was formed by oxidation of the benzylic position with a combination of Cr(CO)6 and t-BuOOH, followed by the introduction of an aminoethyl side chain, C–H oxidation of the lactam ring with CrO3 and n-Bu4NI, and final cyclization to construct the cyclic aminal moiety.
- Sugimoto, Kenji,Fujiwara, Hiroaki,Takada, Akihiro,Kim, Dong-Gil,Ueda, Hirofumi,Tokuyama, Hidetoshi
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p. 1028 - 1049
(2019/07/31)
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- The fluorine-containing silane compound, a coating agent, and water-repellent film
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PROBLEM TO BE SOLVED: To provide a fluorine-containing alkoxy silane compound adaptable to environmental problems and capable of forming a water-repellent film in which a decrease in water repellency accompanied by reduction of the number of fluorine atoms in a perfluoroalkyl group is suppressed and which exhibits water repellency and durability equal to or higher than those when using a conventional fluorine-containing alkoxy silane compound having a perfluoroalkyl group with carbon atoms of 8 or more.SOLUTION: The fluorine-containing alkoxy silane compound is represented by general formula (1): Rf-A-B-SiX. In the general formula (1), Rf represents a 3-7C perfluoroalkyl group, A represents -COO-, -O-, -S- or -CO-S-, B represents -(CH)- (m=5 to 20), and X represents -OCH(n=1 to 4), where three X may be the same or different from each other.
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Paragraph 0062
(2017/05/23)
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- Homologated amino acids with three vicinal fluorines positioned along the backbone: Development of a stereoselective synthesis
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Backbone-extended amino acids have a variety of potential applications in peptide and protein science, particularly if the geometry of the amino acid is controllable. Here we describe the synthesis of d-amino acids that contain three vicinal C-F bonds pos
- Cheerlavancha, Raju,Ahmed, Ahmed,Leung, Yun Cheuk,Lawer, Aggie,Liu, Qing-Quan,Cagnes, Marina,Jang, Hee-Chan,Hu, Xiang-Guo,Hunter, Luke
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supporting information
p. 2316 - 2325
(2017/11/16)
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- Facile synthesis of fluorovinyl-containing lactams via ring-closing metathesis of N-substituted 2-fluoroallylamides
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A cost-efficient method for the preparation of a series of N-substituted 2-fluoroallylamines and their application in the synthesis of fluoroalkene-containing lactams are described. N-substituted 2-fluoroallylamine could be readily synthesized from methyl 2-fluoroacrylate via aminolysis and subsequently selective reduction of the amide group. These amines were further converted into the corresponding amides with diverse acids bearing a terminal double bond. The Ring-Closing Metathesis (RCM) of the resulting amides led to the formation fluorovinyl-containing lactams in good yields.
- Li, Yang,Li, Kai,Wu, Yue,Ma, Qiaoning,Lei, Xinsheng
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p. 4845 - 4853
(2016/07/18)
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- A Chiral Thiourea as a Template for Enantioselective Intramolecular [2 + 2] Photocycloaddition Reactions
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A chiral (1R,2R)-diaminocyclohexane-derived bisthiourea was found to exhibit a significant asymmetric induction in the intramolecular [2 + 2] photocycloaddition of 2,3-dihydropyridone-5-carboxylates. Under optimized conditions, the reaction was performed with visible light employing 10 mol % of thioxanthone as triplet sensitizer. Due to the different electronic properties of its carbonyl oxygen atoms, a directed binding of the substrate to the template is possible, which in turn enables an efficient enantioface differentiation.
- Mayr, Florian,Brimioulle, Richard,Bach, Thorsten
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p. 6965 - 6971
(2016/08/30)
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- UV ABSORBING COMPOUNDS, COMPOSITIONS COMPRISING SAME AND USES THEREOF
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There is provided a range of novel compounds which have been demonstrated to have useful UV absorbing properties. These compounds will find use in a range of applications such as active components in sunscreen formulations, paints, plastics, fabrics, glass and UV protective coatings.
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Paragraph 00133-00134
(2015/02/02)
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- A Titanium(III)-Catalyzed Reductive Umpolung Reaction for the Synthesis of 1,1-Disubstituted Tetrahydroisoquinolines
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A catalytic reductive C1-acylation of 3,4-dihydroisoquinolines is presented that gives direct access to 1,1-disubstituted tetrahydroisoquinolines. The reaction is a titanium(III)-catalyzed reductive umpolung process in which nitriles act as effective acylation agents. The method is highly chemo- and regioselective and is demonstrated in 20 examples. It is well-suited for the large-scale synthesis of functionalized tetrahydroisoquinoline products, which is exemplified in the form of a six-step synthesis of (±)-3-demethoxyerythratidinone. (Figure Presented).
- Luu, Hieu-Trinh,Wiesler, Stefan,Frey, Georg,Streuff, Jan
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supporting information
p. 2478 - 2481
(2015/05/27)
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- Compound And Method
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A compound of formula (I): (I) wherein Y is, Z is OR10, NR11R11 SR11, S(0)R11 S02R11, R10 is H, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted heterocyclyl, CO—R11, or a protecting group, and R11 is optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted heterocyclyl, or alkoxyl; a process for making a compound of formula (I); and a process for making a prostaglandin or a prostaglandin analogue using a compound of formula (I). wherein Y is
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Paragraph 0604-0609
(2015/06/17)
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- Synthesis of Polysubstituted γ-Butenolides via a Radical Pathway: Cyclization of α-Bromo Aluminium Acetals and Comparison with the Cyclization of α-Bromoesters at High Temperature
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Polysubstituted butenolides were obtained in good to high yields from α-bromoesters derived from propargyl alcohols by a one-pot reaction involving the radical cyclization of α-bromo aluminium acetals, followed by the oxidation of the resulting cyclic aluminium acetals in an Oppenauer-type process and migration of the exocyclic C-C bond into the α,β-position. Comparison with the direct cyclization of α-bromoesters at high temperature and under high dilution conditions is described. Deuterium-labelling experiments allowed us to uncover "invisible" 1,5-hydrogen atom transfers (1,5-HATs) that occur during these cyclization processes, together with the consequences of the latter in the epimerization of stereogenic centres. Compared to the classical approach, the cyclization of aluminium acetals proved to be highly chemoselective and its efficiency was illustrated by the short total syntheses of optically enriched γ-butenolides isolated from Plagiomnium undulatum and from Kyrtuhrix maculans.
- Bénéteau, Romain,Despiau, Carole F.,Rouaud, Jean-Christophe,Boussonnière, Anne,Silvestre, Virginie,Lebreton, Jacques,Dénès, Fabrice
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supporting information
p. 11378 - 11386
(2015/08/03)
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- Oxidative catalysis using the stoichiometric oxidant as a reagent: An efficient strategy for single-electron-transfer-induced tandem anion-radical reactions
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Oxidative single-electron transfer-catalyzed tandem reactions consisting of a conjugate addition and a radical cyclization are reported, which incorporate the mandatory terminal oxidant as a functionality into the product. Making waste a functionality: Ox
- Kafka, Frantisek,Holan, Martin,Hidasova, Denisa,Pohl, Radek,Klepetarova, Blanka,Jahn, Ullrich,Cisarova, Ivana
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p. 9944 - 9948,5
(2014/10/15)
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- Iron-catalysed chemo-, regio-, and stereoselective hydrosilylation of alkenes and alkynes using a bench-stable iron(II) pre-catalyst
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The chemo-, regio-, and stereoselective iron-catalysed hydrosilylation of alkenes and alkynes with excellent functional group tolerance is reported (34 examples, 41-96% yield). The catalyst and reagents are commercially available and easy to handle, with the active iron catalyst being generated in situ, thus providing a simple and practical methodology for iron-catalysed hydrosilylation. The silane products can be oxidised to the anti-Markovnikov product of olefin hydration, and the one-pot iron-catalysed hydrosilylation-oxidation of olefins to give silane(di)ols directly is also reported. The iron pre-catalyst was used at loadings as low as 0.07 mol%, and displayed catalyst turnover frequencies (TOF) approaching 60,000 molh-1. Initial mechanistic studies indicate an iron(I) active catalyst.
- Greenhalgh, Mark D.,Frank, Dominik J.,Thomas, Stephen P.
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supporting information
p. 584 - 590
(2014/05/20)
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- Iron-catalysed, general and operationally simple formal hydrogenation using Fe(OTf)3 and NaBH4
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An operationally simple and environmentally benign formal hydrogenation protocol has been developed using highly abundant iron(iii) salts and an inexpensive, bench stable, stoichiometric reductant, NaBH4, in ethanol, under ambient conditions. This reaction has been applied to the reduction of terminal alkenes (22 examples, up to 95% yield) and nitro-groups (26 examples, up to 95% yield). Deuterium labelling studies indicate that this reaction proceeds via an ionic rather than radical mechanism.
- MacNair, Alistair J.,Tran, Ming-Ming,Nelson, Jennifer E.,Sloan, G. Usherwood,Ironmonger, Alan,Thomas, Stephen P.
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supporting information
p. 5082 - 5088
(2014/07/08)
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- Synthesis of fused 3-aminoazepinones via trapping of a new class of cyclic seven-membered allenamides with furan
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Novel tricyclic tetrahydroazepinones were synthesized via an in situ Diels-Alder reaction of furan with cyclic allenamides. These reactive intermediates are the first examples of cyclic seven-membered allenamides and were prepared starting from N-(2-chlor
- Schurgers, Ben,Brigou, Ben,Urbanczyk-Lipkowska, Zofia,Tourwe, Dirk,Ballet, Steven,De Proft, Frank,Van Lommen, Guy,Verniest, Guido
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p. 3712 - 3715
(2014/08/05)
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- Deuterium and tritium labelling of N-acyl-L-homoserine lactones (AHLs) by catalytic reduction of a double bond in the layer-by-layer method
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N-Acyl-L-homoserine lactones (AHLs) are signalling molecules found in Gram-negative bacteria that enable bacteria to communicate with each other through quorum sensing and with their eukaryotic host cells through inter-kingdom signalling. Very little is known about inter-kingdom signalling mechanisms. Deuterium- and tritium-labelled AHLs were synthesized in an effort to detect the cellular distribution and monitor the membrane transport of AHLs. Most tritium labelling methods use tritium gas, which is difficult to handle, however, here we present a novel, gas-free method with which to obtain deuterium- and tritium-label terminally unsaturated AHLs through catalytic reduction of the double bond. This uncommon double bond reduction employs either sodium borohydride-[2H] or sodium borohydride-[3H] and is performed in the presence of palladium(II) acetate, which acts as a catalyst in the unique layer-by-layer system. Moreover, detailed NMR analysis of the resulting isotopologues is presented. A novel, gas-free method of deuterium- and tritium-labelling of terminally unsaturated AHLs is described. The catalytic reduction of the double bond by sodium borohydrides is performed in the presence of palladium(II) acetate, which acts as a catalyst in the unique layer-by-layer system. Copyright
- Jakubczyk, Dorota,Merle, Christian,Brenner-Weiss, Gerald,Luy, Burkhard,Braese, Stefan
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p. 5323 - 5330
(2013/09/02)
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- Low catalyst loading in ring-closing metathesis reactions
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An efficient procedure is described for ring-closing metathesis reactions. A conversion of 95 % for diethyl diallylmalonate in dilute solution could be achieved within a few minutes, reaching TOF=4173min-1, with very low loading of commercially available Ru catalysts that contained unsaturated NHC ligands. In general, only 50 to 250ppm of the catalyst is required to achieve near-quantitative conversion into a broad variety of 5-16-membered heterocyclic compounds. The practicality of this procedure was illustrated in the synthesis of 5-8-membered N-tert-butoxycarbonyl (N-Boc)- and N-para-toluenesulfonyl (N-Ts)-protected cyclic amines and 9-16-membered lactones. The synthesis of macrocyclic proline-based lactams required slightly higher catalyst loadings. Along with monocyclic products, oligomeric byproducts, mostly cyclodimers, were isolated and characterized. Getting some closure: An efficient procedure is described for ring-closing metathesis reactions in which only 50 to 250ppm of catalyst is required to effect almost-quantitative conversion into a broad range of 5-16-membered heterocyclic compounds. The practicality of this procedure was illustrated in the synthesis of 5-8-membered N-protected cyclic amines, 9-16-membered lactones, and 11-16-membered proline-based lactams. Copyright
- Kadyrov, Renat
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supporting information
p. 1002 - 1012
(2013/02/23)
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- Macrolides and alcohols as scent gland constituents of the Madagascan frog mantidactylus femoralis and their intraspecific diversity
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Acoustic and, to a lesser degree, visual signals are the predominant means of signaling in frogs. Nevertheless, certain lineages such as the mantelline frogs from Madagascar use the chemical communication channel as well. Males possess femoral glands on the hind legs, which recently have been shown to contain volatile compounds used in communication as pheromones. Many mantelline species occur in sympatry, and so far species recognition is regarded to occur mainly by acoustic signals. The analysis of the gland constituents of Mantidactylus femoralis by GC/MS revealed the presence of volatile macrolides and secondary alcohols. The new natural products mantidactolides A (4) and B (6), as well as several methyl carbinols, were identified, and their structures were confirmed by synthesis. The analysis of individuals from different locations of Madagascar revealed the presence of two groups characterized by specific patterns of compounds. While one group contained the alcohols and mantidactolide B, the other showed specific presence of the macrolides phoracantholide I (1) and mantidactolide A (4). Genetic analysis of some individuals showed no congruence between genetic relatedness and gland constituents. Several other individuals from related species had different gland compositions. This suggests that a basic set of biosynthetic machinery might be available to a broader group of related species.
- Poth, Dennis,Peram, Pardha Saradhi,Vences, Miguel,Schulz, Stefan
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supporting information
p. 1548 - 1558
(2013/10/22)
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- Synthesis and biological evaluation of arylthiourea derivatives with antitubercular activity
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Tuberculosis (TB) is a contagious disease caused by Mycobacterium tuberculosis (M. tuberculosis), and remains one of the most life-threatening plagues for public health in the world. The emergence of drug resistant strains of TB and co-infection with HIV has further complicated TB treatment. Here, the synthesis and characterizaton of a series of compounds were described, and these were followed by evaluating for their antibacterial activity against M. tuberculosis. Several novel arylthiourea derivatives exhibited excellent activity (lowest MIC=0.09 μg/ml) against M. tuberculosis including drug resistant strains of M. tuberculosis. The results suggest that these compounds are promising candidates for new anti-TB agent development.
- Luo, Rusong,Laitinen, Tuomo,Teng, Liyan,Nevalainen, Tapio,Lahtela-Kakkonen, Maija,Zheng, Baofu,Wang, Honghai,Poso, Antti,Zhang, Xuelian
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p. 640 - 650
(2013/08/23)
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- COMPOUND AND METHOD
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A compound of formula (I): (I) wherein Y is, Z is OR10, NR11R11 SR11, S(0)R11 S02R11, R10 is H, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted heterocyclyl, CO-R11, or a protecting group, and R11 is optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted heterocyclyl, or alkoxyl; a process for making a compound of formula (I); and a process for making a prostaglandin or a prostaglandin analogue using a compound of formula (I).
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Page/Page column 114
(2014/01/08)
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- Palladium-catalyzed allylic alkylation of carboxylic acid derivatives: N-acyloxazolinones as ester enolate equivalents
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Triple A: A general asymmetric allylic alkylation of ester enolate equivalents at the carboxylic acid oxidation state is reported. N-Acylbenzoxazolinone-derived enol carbonates were synthesized and employed in the palladium-catalyzed alkylation reaction. The imide products were readily converted into a series of carboxylic acid derivatives without loss of enantiopurity.
- Trost, Barry M.,Michaelis, David J.,Charpentier, Julie,Xu, Jiayi
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supporting information; experimental part
p. 204 - 208
(2012/02/16)
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- Palladium-catalyzed dehydrogenative β'-functionalization of β-keto esters with indoles at room temperature
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The dehydrogenative β'-functionalization of α-substituted β-keto esters with indoles proceeds with high regioselectivities (C3-selective for the indole partner and β′-selective for the β-keto ester) and good yields under mild palladium catalysis at room temperature with a variety of oxidants. Two possible mechanisms involving either late or early involvement of indole are presented.
- Leskinen, Mikko V.,Yip, Kai-Tai,Valkonen, Arto,Pihko, Petri M.
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supporting information; experimental part
p. 5750 - 5753
(2012/05/07)
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- Fe(III)/NaBH4-mediated free radical hydrofluorination of unactivated alkenes
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A powerful Fe(III)/NaBH4-mediated free radical hydrofluorination of unactivated alkenes is disclosed using Selectfluor reagent as a source of fluorine and resulting in exclusive Markovnikov addition. In contrast to the traditional and unmanageable free radical hydrofluorination of alkenes, the Fe(III)/NaBH4-mediated reaction is conducted under exceptionally mild reaction conditions (0 °C, 5 min, CH3CN/H2O). The reaction can be conducted open to the air and with water as a cosolvent and demonstrates an outstanding substrate scope and functional group tolerance.
- Barker, Timothy J.,Boger, Dale L.
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supporting information; experimental part
p. 13588 - 13591
(2012/10/08)
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- Convenient synthesis and cyclization of dimeric abasic PNA
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The synthesis of an abasic PNA-based dimer block has been achieved. An alkyl chain stapling the two base sites conformationally restricts the PNA backbone, and serves as an example of preorganization by direct base site linkage. Other possible examples of
- Cooper, Daniel C.,Suggs, J. William
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supporting information
p. 6943 - 6945
(2013/01/15)
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- Palladium-catalyzed ring-contraction and ring-expansion reactions of cyclic allyl amines
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Ring around the rosy: An amino group can act as the leaving group or the nucleophile in a palladium-catalyzed allylic amination. As a result, readily accessible cyclic amines can be either ring contracted or ring expanded (see scheme).
- Dubovyk, Igor,Pichugin, Dmitry,Yudin, Andrei K.
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supporting information; experimental part
p. 5924 - 5926
(2011/08/04)
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- Efficient regio- And stereoselective formation of azocan-2-ones via 8-endo cyclization of α-carbamoyl radicals
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The iodine-atom-transfer 8-endo cyclization of α-carbamoyl radicals was investigated experimentally and theoretically. With the aid of Mg(CIO 4)2 and a bis(oxazoline) ligand, N- ethoxycarbonylsubstituted N-(pent-4-enyl)-2-iodoalkanamides underwent 8-endo cyclization leading to the formation of only the corresponding 3,5-trans-substituted azocan-2-ones in excellent yields. Similarly, the BF 3·OEt2/H2O-promoted reactions of N-ethoxycarbonyl-N-(2-allylaryl)-2-iodoalkanamides afforded exclusively the benzazocanone products with a 3,5-cis configuration in high yields. The bidentate chelation of substrate radicals not only significantly improved the efficiency of cyclization but also resulted in the change of stereochemistry of azocanone products from 3,8-iransto 3,8-cis. Theoretical calculations at the UB3LYP/6-31G* level revealed that the cyclization of N-carbonyl- substituted α-carbamoyl radicals occurs via the E-conformational transition states without the presence of a Lewis acid. On the other hand, the cyclization proceeds via the Z-conformational transition states when the substrates form the bidentate chelation with a Lewis acid. In both cases, the 8-endo cyclization is always fundamentally preferred over the corresponding 7-exo cyclization. The complexed radicals having the more rigid conformations also allow the better stereochemical control in the iodine-atom-abstraction step. To further understand the reactivity of a-carbamoyl radicals, the competition between the 8-endo and 5-exo cyclization was also studied. The results demonstrated that the 8-endo cyclization is of comparable rate to the corresponding 5-exo cyclization for a-carbamoyl radicals with fixed Z-conformational transition states. As a comparison, the 8-endo mode is fundamentally preferred over the 5-exo mode in the cyclization of NH-amide substrates because the latter requires the Z-conformational transition states, whereas the former proceeds via the more stable E-conformational transition states.
- Fang, Xinqiang,Liu, Kun,Li, Chaozhong
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supporting information; experimental part
p. 2274 - 2283
(2010/05/01)
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- Platinum-catalyzed intramolecular hydrohydrazination: Evidence for alkene insertion into a Pt-n bond
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Dicationic (bpy)Pt(II) complexes were found to catalyze the intramolecular hydrohydrazination of alkenes. Reaction optimization revealed Pt(bpy)Cl 2 (10 mol %) and AgOTf (20 mol %) in DMF-d7 to be an effective catalyst system for the conversion of substituted hydrazides to five- and six-membered N-amino lactams (N-amino = N-acetamido at 120 A°C, N-phthalimido at 80 A°C, -OTf = trifluoromethanesulfonate). Of the four possible regioisomeric products, only the product of 5-exo cyclization at the proximal nitrogen is formed, without reaction at the distal nitrogen or 6-endo cyclization. The resting states were found to be a 2:1 Pt-amidate complex (25, for N-acetamido) of the deprotonated hydrazide and a Pt-alkyl complex of the cyclized pyrrolidinone (20 for N-phthalimido). Both complexes are catalytically competent. Catalysis using 25 as the precatalyst shows no rate dependence on added acid (HOTf) or base (2,6-lutidine). The available mechanistic data are all consistent with a mechanism involving N-H activation of the hydrazide, followed by insertion of the alkene into the Pt-N bond, and finally protonation of the resulting cyclized alkyl complex by hydrazide to release the hydrohydrazination product and regenerate the active Pt-amidate catalyst.
- Hoover, Jessica M.,Dipasquale, Antonio,Mayer, James M.,Michael, Forrest E.
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supporting information; body text
p. 5043 - 5053
(2010/06/13)
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- Stereoselective syntheses of trisubstituted olefins via platinum catalysis: α-Silylenones with geometrical complementarity
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The stereoselective syntheses of α-silylenones using catalytic PtCl2 are reported. Via alkyne activation, α- hydroxypropargylsilanes are converted to (Z)-silylenones through a highly selective silicon migration. The complementary (E)-silylenone
- Rooke, Douglas A.,Ferreira, Eric M.
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supporting information; experimental part
p. 11926 - 11928
(2010/11/16)
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- Iron-catalyzed addition of Grignard reagents to activated vinyl cyclopropanes
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A highly regioselective iron-catalyzed addition of branched primary, secondary or tertiary alkyl Grignard reagents to activated vinyl cyclopropanes is described, which likely proceeds by a direct addition mechanism as opposed to single electron transfer or an iron-allyl based process. The Royal Society of Chemistry 2009.
- Sherry, Benjamin D.,Fuerstner, Alois
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supporting information; experimental part
p. 7116 - 7118
(2010/03/25)
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- Searching for new NO-donor aspirin-like molecules: A new class of nitrooxy-acyl derivatives of salicylic acid
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A new class of products in which the phenol group of salicylic acid is linked to alkanoyl moieties bearing nitrooxy functions has been synthesized and studied for their polyvalent actions. The products were stable in acid and neutral media, while they were hydrolyzed in human serum. Their half-lives were dependent upon the structure of alkanoyl moieties. The products showed anti-inflammatory activities similar to aspirin when tested in the carrageenan-induced paw edema assay in the rat. Interestingly, unlike aspirin, they showed reduced or no gastrotoxicity in a lesion model in rats at equimolar doses. A number of them were able to inhibit platelet aggregation induced by collagen in human platelet-rich plasma. All of the products were capable of relaxing rat aortic strips precontracted with phenylephrine in a concentration-dependent manner. Selected members of this new class of nonsteroidal anti-inflammatory drugs might represent possible safer alternatives to aspirin in different clinical settings.
- Lazzarato, Loretta,Donnola, Monica,Rolando, Barbara,Marini, Elisabetta,Cena, Clara,Coruzzi, Gabriella,Guaita, Elena,Morini, Giuseppina,Fruttero, Roberta,Gasco, Alberto,Biondi, Stefano,Ongini, Ennio
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p. 1894 - 1903
(2008/12/20)
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- Diastereoselective synthesis of cyclopentapyridazinones via radical cyclization: Synthetic studies toward halichlorine
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(Equation Presented) The pyridazinone ring system serves as an excellent scaffold for the diastereoselective preparation of novel cis-fused cyclopentapyridazinones utilizing the directed 5-exo radical cyclization approach. This overall approach was succes
- Keck, Gary E.,Neumann, Stacey A.
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supporting information; experimental part
p. 4783 - 4786
(2009/05/31)
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- Substrate encapsulation: An efficient strategy for the RCM synthesis of unsaturated ε-lactones
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(Chemical Equation Presented) A facile substrate-encapsulated RCM-based synthesis of 7-membered lactones is reported. Coordination of the α,ω-dienyl ester precursor to the bulky Lewis acid (LA) aluminum tris(2,6-diphenylphenoxide) (ATPH) provides a protective extended steric pocket to the olefin moieties, thereby favoring intramolecular RCM over intermolecular ADMET oligomerization. The LA-encapsulated esters undergo ring-closure in the presence of Ru-based olefin metathesis catalysts to give previously difficult-to-access 7-membered β,γ- and γ,δ-unsaturated lactones in good yields.
- Pentzer, Emily B.,Gadzikwa, Tendai,Nguyen, Sonbinh T.
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supporting information; experimental part
p. 5613 - 5615
(2009/06/18)
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- Synthesis of (±)-4-alkanolides from pent-4-enoic acid
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Synthesis of (±)-4-hexanolide, (±)-4-nonanolide, and (±)-4-dodecanolide, racemic forms of the insect signal substances, has been accomplished by cationic cyclization of pent-4-enoic acid and its amide in the key step.
- Ugurchieva,Lozanova,Zlokazov,Veselovsky
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experimental part
p. 657 - 659
(2009/05/16)
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- SALICYLIC ACID DERIVATIVES
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The present invention refers to O-acyl salicylic acid derivatives (I) bearing a NO donor moiety, a process for their preparation and pharmaceutical compositions containing them. (I) wherein : D is ONO2 or (A).
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Page/Page column 35-36
(2008/06/13)
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- Ligand effects in the synthesis of N-heterocycles by intramolecular Heck reactions
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Chemo- and regioselectivity of intramolecular Heck reactions are dependent on the type of ligand employed. Six- to eight-membered benzolactams are produced in good yields using PPh3 as ligand. In contrast, a biaryl coupling occurred preferentially under ligandless conditions to form a dihydrophenanthridine product. Conformations of the seven- and eight-membered benzolactams in the solid state were examined by X-ray crystallography.
- Cropper, Emma L.,White, Andrew J. P.,Ford, Agnes,Hii, King Kuok
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p. 1732 - 1735
(2007/10/03)
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