- Rh2(OAc)4-mediated decomposition of diazocarbonyl compounds: A comparison of α-diazo ketones and α-diazo β-keto esters reactivity
-
Unsaturated α-diazocarbonyl compounds undergo intramolecular cyclopropanation or carbon-hydrogen bond insertion when catalyzed by Rh2(OAc)4: α-diazo ketones react preferentially with carbon-carbon doubled bond, whereas closely related α-diazo-β-keto-esters insert into carbon-hydrogen bond.
- Ceccherelli, Paolo,Curini, Massimo,Marcotullio, Maria Carla,Rosati, Ornelio
-
-
Read Online
- A New Organocatalytic Desymmetrization Reaction Enables the Enantioselective Total Synthesis of Madangamine e
-
The enantioselective total synthesis of madangamine E has been completed in 30 steps, enabled by a new catalytic and highly enantioselective desymmetrizing intramolecular Michael addition reaction of a prochiral ketone to a tethered β,β′-disubstituted nit
- Dixon, Darren J.,Fuentes De Arriba, ángel L.,Hamlin, Trevor A.,Shennan, Benjamin D. A.,Shiomi, Shinya,Vasu, Dhananjayan,Yamazaki, Ken
-
supporting information
p. 1407 - 1415
(2022/02/05)
-
- A Unified Approach to Polycyclic Alkaloids of the Ingenamine Estate: Total Syntheses of Keramaphidin B, Ingenamine, and Nominal Njaoamine i
-
Many polycyclic marine alkaloids are thought to derive from partly reduced macrocyclic alkylpyridine derivatives via a transannular Diels-Alder reaction that forms their common etheno-bridged diaza-decaline core ("Baldwin-Whitehead hypothesis"). Rather th
- Meng, Zhanchao,Spohr, Simon M.,Tobegen, Sandra,Farès, Christophe,Fürstner, Alois
-
supporting information
p. 14402 - 14414
(2021/09/13)
-
- Lessons in Strain and Stability: Enantioselective Synthesis of (+)-[5]-Ladderanoic Acid
-
The synthesis of structurally complex and highly strained natural products provides unique challenges and unexpected opportunities for the development of new reactions and strategies. Herein, the synthesis of (+)-[5]-ladderanoic acid is reported. En route to the target, unusual and unexpected strain release driven transformations were uncovered. This occurrence required a drastic revision of the synthetic design that ultimately led to the development of a novel stepwise cyclobutane assembly by an allylboration/Zweifel olefination sequence.
- Hancock, Erin N.,Kuker, Erin L.,Tantillo, Dean J.,Brown, M. Kevin
-
supporting information
p. 436 - 441
(2019/11/25)
-
- Carbamate as an accelerating group in intermolecular Pauson-Khand reaction
-
The Pauson-Khand reaction (PKR) is a powerful means for the construction of cyclopentenones. However, its applications have been limited to the intramolecular version of this reaction because poor yield and regioselectivity are often the major problems in intermolecular PKR. Here we describe that a carbamate moiety in alkene substrate accelerates this intermolecular PKR. The reaction of N-4-dimethylaminophenyl O-allyl carbamate with alkyne-cobalt complex gave cyclopentenones in high yield (up to 90%) and regioselectivity (>9:1).
- Asano, Shota,Itto-Nakama, Kaori,Arimoto, Hirokazu
-
-
- SPIRO-SULFONAMIDE DERIVATIVES AS INHIBITORS OF MYELOID CELL LEUKEMIA-1 (MCL-1) PROTEIN
-
The disclosure is directed to compounds of Formula I (I) Pharmaceutical compositions comprising compounds of Formula I as well as methods of their use and preparation, are also described.
- -
-
Paragraph 00625
(2020/06/01)
-
- Viaticene A – An Unusual Tetraterpene Cuticular Lipid Isolated from the Springtail Hypogastrura viatica
-
The cuticles of springtails are extremely wear- and friction-resistant, super-hydrophobic, non-fouling, and self-cleaning. As such, the chemistry of the lipids covering these cuticles is of great interest as a model for biomimetic super-hydrophobic surfaces, although only few of these lipids have been structurally elucidated. Hypogastrura viatica, a surface-dwelling springtail, produces highly branched tetraterpene hydrocarbons with an unprecedented [6+2]-terpene connectivity as components of the epicuticular lipid layer. The structure of the major lipid component, viaticene A, was elucidated through isolation, spectroscopic analysis, chemical derivatization, synthesis, as well as stereochemical analysis of the core unit obtained from ozonolysis of the isolated lipid. Viaticenes A and B represent a new class of irregular tetraterpenoid natural products.
- Bello, Jan E.,Stamm, Patrick,Leinaas, Hans Petter,Schulz, Stefan
-
supporting information
p. 2158 - 2162
(2019/03/17)
-
- CYCLIC PEPTIDE ANTIBIOTICS
-
Provided herein are antibacterial compounds, wherein the compounds in some embodiments have broad spectrum bioactivity. In various embodiments, the compounds act by inhibition of lipoprotein signal peptidase II (LspA), a key protein in bacteria. Pharmaceutical compositions and methods for treatment using the compounds described herein are also provided.
- -
-
Paragraph 00436
(2019/04/11)
-
- Fungicidal Properties of Some Novel Trifluoromethylphenyl Amides
-
Trifluoromethylphenyl amides (TFMPAs) were designed and synthesized as potential pesticides. Thirty-three structures were evaluated for fungicidal activity against three Colletotrichum species using direct bioautography assays. Active compounds were subsequently tested against C. fragariae, C. gloeosporioides, C. acutatum, Phomopsis obscurans, P. viticola, Botrytis cinerea and Fusarium oxysporum. The study identified 2-chloro-N-[2,6-dichloro-4-(trifluoromethyl)phenyl]acetamide (7a) as showing the strongest antifungal activity, and the broadest activity spectrum in this set against Colletotrichum acutatum (at 48 and 72 h) and Phomopsis viticola (at 144 h). The presence of triethylamine in its complex with N-[2,6-dichloro-4-(trifluoromethyl)phenyl]-2,2,3,3,3-pentafluoropropanamide (7b′) played an important role in the bioactivity, and depending on the concentration or fungal species it showed higher or lower activity than the parent amide. X-Ray crystallography has shown that the complex (7b′) is an ion pair, (C10H2Cl2F8NO)? (C6H16N)+, where a proton is transferred from the amide nitrogen to the triethylamine nitrogen and then connected by hydrogen bonding to the acyl oxygen (N?H 0.893 ?; H???O 1.850 ?; N???O 2.711 ?; N?H???O 161.2(13)°). Although none of these compounds were better than standards, this work revealed some potential lead structures for further development of active novel compounds.
- Tsikolia, Maia,Bernier, Ulrich R.,Wedge, David E.,Tabanca, Nurhayat,Abboud, Khalil A.,Linthicum, Kenneth J.
-
-
- Synthesis of Ynolates via Double Deprotonation of Nonbrominated Esters
-
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
-
supporting information
p. 6585 - 6588
(2019/09/30)
-
- Non- C2-Symmetric Chiral-at-Ruthenium Catalyst for Highly Efficient Enantioselective Intramolecular C(sp3)-H Amidation
-
A new class of chiral ruthenium catalysts is introduced in which ruthenium is cyclometalated by two 7-methyl-1,7-phenanthrolinium heterocycles, resulting in chelating pyridylidene remote N-heterocyclic carbene ligands (rNHCs). The overall chirality results from a stereogenic metal center featuring either a or Δabsolute configuration. This work features the importance of the relative metal-centered stereochemistry. Only the non-C2-symmetric chiral-at-ruthenium complexes display unprecedented catalytic activity for the intramolecular C(sp3)-H amidation of 1,4,2-dioxazol-5-ones to provide chiral -lactams with up to 99:1 er and catalyst loadings down to 0.005 mol % (up to 11 ?200 TON), while the C2-symmetric diastereomer favors an undesired Curtius-type rearrangement. DFT calculations elucidate the origins of the superior C-H amidation reactivity displayed by the non-C2-symmetric catalysts compared to related C2-symmetric counterparts.
- Zhou, Zijun,Chen, Shuming,Hong, Yubiao,Winterling, Erik,Tan, Yuqi,Hemming, Marcel,Harms, Klaus,Houk,Meggers, Eric
-
supporting information
p. 19048 - 19057
(2019/12/04)
-
- Synergistic Visible-Light Photoredox/Nickel-Catalyzed Synthesis of Aliphatic Ketones via N-C Cleavage of Imides
-
An electrophilic, imide-based, visible-light-promoted photoredox/Ni-catalyzed cross-coupling reaction for the synthesis of aliphatic ketones has been developed. This protocol proceeds through N-C(O) bond activation, made possible through the lower activation energy for metal insertion into this bond due to delocalization of the lone pair of electrons on the nitrogen by electron-withdrawing groups. The operationally simple and mild cross-coupling reaction is performed at ambient temperature and exhibits tolerance for a variety of functional groups.
- Amani, Javad,Alam, Rauful,Badir, Shorouk,Molander, Gary A.
-
supporting information
p. 2426 - 2429
(2017/05/12)
-
- Facile synthesis of fluorovinyl-containing lactams via ring-closing metathesis of N-substituted 2-fluoroallylamides
-
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
-
p. 4845 - 4853
(2016/07/18)
-
- Low catalyst loading in ring-closing metathesis reactions
-
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
-
p. 1002 - 1012
(2013/02/23)
-
- Screening of a selection of commercially available homogeneous Ru-catalysts in valuable olefin metathesis transformations
-
A library of thirteen different commercially available Ru-based catalysts was evaluated in valuable metathesis reactions for the production of fragrance and bioactive molecule precursors. Rigorous library screening clearly illustrated the different catalytic behaviour of the catalyst selection and highlighted its significant advantage to provide efficiency in specific metathesis applications. Interestingly, this strategy offered substantial improvement over the state of the art, with the efficient synthesis of the macrocyclic Exaltolide 2 at low catalyst loading and dilution conditions. The Royal Society of Chemistry 2013.
- Caijo, Frederic,Tripoteau, Fabien,Bellec, Aurelien,Crevisy, Christophe,Basle, Olivier,Mauduit, Marc,Briel, Oliver
-
p. 429 - 435
(2013/03/14)
-
- Stereoselective access to Z and e macrocycles by ruthenium-catalyzed Z-selective ring-closing metathesis and ethenolysis
-
The first report of Z-selective macrocyclizations using a ruthenium-based metathesis catalyst is described. The selectivity for Z macrocycles is consistently high for a diverse set of substrates with a variety of functional groups and ring sizes. The same catalyst was also employed for the Z-selective ethenolysis of a mixture of E and Z macrocycles, providing the pure E isomer. Notably, an ethylene pressure of only 1 atm was required. These methodologies were successfully applied to the construction of several olfactory macrocycles as well as the formal total synthesis of the cytotoxic alkaloid motuporamine C.
- Marx, Vanessa M.,Herbert, Myles B.,Keitz, Benjamin K.,Grubbs, Robert H.
-
supporting information
p. 94 - 97
(2013/04/10)
-
- Intramolecular [2+2] cycloaddition of homoallylketenes to bicyclo[2.1.1]hexan-5-ones
-
Intramolecular [2+2] cycloaddition of γ,δ-unsaturated ketenes derived from hex-5-enoyl chloride derivatives gave bicyclo[2.1.1]hexan-5-ones with complete regioselectivity.
- Hoshikawa, Takaya,Tanji, Kei,Matsuo, Jun-Ichi,Ishibashi, Hiroyuki
-
experimental part
p. 548 - 553
(2012/05/05)
-
- Total synthesis of bistramide A and its 36(Z) isomers: Differential effect on cell division, differentiation, and apoptosis
-
The total synthesis of bistramide A and its 36(Z),39(S) and 36(Z),39(R) isomers shows that these compounds have different effects on cell division and apoptosis. The synthesis relies on a novel enol ether-forming reaction for the spiroketal fragment, a kinetic oxa-Michael cyclization reaction for the tetrahydropyran fragment, and an asymmetric crotonylation reaction for the amino acid fragment. Preliminary biological studies show a distinct pattern of influence of each of the three compounds on cell division, differentiation, and apoptosis in HL-60 cells, thus suggesting that these effects are independent activities of the natural product. Copyright
- Tomas, Loic,Boije Af Gennaes, Gustav,Hiebel, Marie Aude,Hampson, Peter,Gueyrard, David,Pelotier, Beatrice,Yli-Kauhaluoma, Jari,Piva, Olivier,Lord, Janet M.,Goekjian, Peter G.
-
supporting information; experimental part
p. 7452 - 7466
(2012/07/28)
-
- The synthesis of 12-membered macrocycles containing a C1-C8 alkene unit via ring-closing metathesis
-
Model cross and ring-closing metathesis strategies toward the C1-C8-linear carbon skeleton are presented. The introduction of a four-atom tether enables the formation of 12-membered rings in good-to-excellent yields and stereoselectivity. Furthermore, the study revealed that the cross-metathesis approach and the formation of medium ring sizes via ring-closing metathesis are much less favorable.
- Po?gan, Franc,?tefane, Bogdan,Kiemet, Davor,Smodi?, Janez,Zupet, Rok
-
supporting information; experimental part
p. 5081 - 5086
(2012/07/28)
-
- Z-SELECTIVE RING-CLOSING METATHESIS REACTIONS
-
The present invention relates generally to olefin metathesis. In some embodiments, the present invention provides methods for Z-selective ring-closing metathesis.
- -
-
Page/Page column 184
(2013/02/28)
-
- Application of a metathesis reaction in the synthesis of sterically congested medium-sized rings. A direct ring closing versus a double bond migration-ring closing process
-
An efficient double bond migration-ring closing metathesis reaction leading to cycloheptene derivatives is observed when specific sterically congested 1,9-dienes are treated with the Grubbs' imidazolidene ruthenium catalyst. The simultaneous use of the Grubbs' catalyst and RuClH(CO)(PPh3) 3 facilitates the tandem bond migration-metathesis process. RuClH(CO)(PPh3)3 alone is capable of triggering an unactivated double bond migration that may have preparative applications.
- Michalak, Michal,Wicha, Jerzy
-
p. 3439 - 3446
(2011/06/19)
-
- Molecular complexity via C-H activation: A dehydrogenative Diels-Alder reaction
-
Traditionally, C-H oxidation reactions install oxidized functionality onto a preformed molecular skeleton, resulting in a local molecular change. The use of C-H activation chemistry to construct complex molecular scaffolds is a new area with tremendous potential in synthesis. We report a Pd(II)/bis-sulfoxide- catalyzed dehydrogenative Diels-Alder reaction that converts simple terminal olefins into complex cycloadducts in a single operation.
- Stang, Erik M.,White, M. Christina
-
supporting information; experimental part
p. 14892 - 14895
(2011/11/01)
-
- Efficient total synthesis of marine alkaloid (-)-nakadomarin A
-
Z's top: For the total synthesis of the marine alkaloid (-)-nakadomarin A, (-)-camphorsulfonic acid assisted, Z-selective, olefin RCM of a monoamine (less polar) rather than a diamine (more polar) was found to be highly practical for constructing the F ring. The ABCD-tetracyclic core was assembled through a novel efficacious PtCl2-promoted cascade reaction sequence (see scheme).
- Cheng, Bin,Wu, Fufang,Yang, Xiaobao,Zhou, Yuedong,Wan, Xiaolong,Zhai, Hongbin
-
supporting information; experimental part
p. 12569 - 12572
(2011/12/04)
-
- Platinum-catalyzed intramolecular hydrohydrazination: Evidence for alkene insertion into a Pt-n bond
-
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.
-
supporting information; body text
p. 5043 - 5053
(2010/06/13)
-
- Stereoselective synthesis of the C1-C13 fragment of bistramide A
-
The C1-C13 fragment of bistramide A was prepared from 5-hexenoic acid in 15 linear steps and in 16% overall yield. The core 2,6-trans-tetrahydropyran ring was obtained via a kinetically controlled oxa- Michael cyclization from the corresponding chiral α,β
- Hiebel, Marie-Aude,Pelotier, Béatrice,Piva, Olivier
-
scheme or table
p. 5091 - 5093
(2011/01/12)
-
- Trimethylsilyldiazomethane as a versatile stitching agent for the introduction of aziridines into functionalized organic molecules
-
A highly enantioselective route for the introduction of aziridines into functionalized organic molecules was developed via a tandem acylation and aziridination of TMSCHN2.
- Ren, Hong,Wulff, William D.
-
supporting information; experimental part
p. 4908 - 4911
(2011/02/21)
-
- A study of tautomerism in N,N-dialkyl-4(5)-bromoalkanecarboxamides
-
N,N-Dialkyl-4-bromobutanamides exist in solution in tautomeric equilibrium with N,N-dialkyl-N-(tetrahydrofuran-2-ylidene)ammonium bromides, while related 4,5-dibromopentanamides show no similar interconversions with the corresponding iminium salts. A simi
- Lozanova,Stepanov,Veselovsky
-
experimental part
p. 1237 - 1241
(2011/02/23)
-
- SUBSTITUTED ARYLCYCLOPENTENES AS THERAPEUTIC AGENTS
-
Disclosed herein is a compound of the formula (I). Therapeutic methods, compositions, and medicaments, related thereto are also disclosed.
- -
-
Page/Page column 34
(2008/12/07)
-
- Effect of substitution on the intramolecular 1,3-dipolar cycloaddition of alkene tethered muenchnones
-
(Chemical Equation Presented) A sequence of chemoselective activation of N-acylaminoacids, muenchnone generation, intramolecular 1,3-dipolar cycloaddition, and ring opening efficiently generated functionalized polycyclic structures such as cyclopenta[b]py
- Belanger, Guillaume,April, Myriam,Dauphin, Etienne,Roy, Stephanie
-
p. 1104 - 1111
(2007/10/03)
-
- First enantioselective total synthesis of the angucyclinone-type antibiotic YM-181741
-
A simple and efficient strategy for angucyclinone antibiotics is described with the disclosure of first total synthesis of YM-181741. Georg Thieme Verlag Stuttgart.
- Kaliappan, Krishna P.,Ravikumar, Velayutham
-
p. 977 - 979
(2008/02/02)
-
- HCV NS3 protease inhibitors
-
The present invention relates to macrocyclic compounds of formula (I) that are useful as inhibitors of the hepatitis C virus (HCV) NS3 protease, their synthesis, and their use for treating or preventing HCV infections.
- -
-
Page/Page column 79
(2008/06/13)
-
- Ligand effects in the synthesis of N-heterocycles by intramolecular Heck reactions
-
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
-
p. 1732 - 1735
(2007/10/03)
-
- Practical asymmetric synthesis of a non-peptidic αvβ 3 antagonist
-
(Chemical Equation Presented) The development of a practical and highly convergent synthesis of an αvβ3 antagonist is described. The two key fragments present in this compound, a tetrahydropyrido[2,3-b]azepine ring system and a chiral 3-aryl-5-oxopentanoic acid, were constructed independently and then coupled at a late stage using a Wittig reaction. The pyridoazepine moiety was prepared from N-Boc 6-chloro-2-aminopyridine via directed ortho-metalation/alkylation followed by in situ cyclization. A Suzuki reaction was then used to attach the propionaldehyde side-chain required for Wittig coupling. The coupling partner was prepared from asymmetric methanolysis of a 3-substituted glutaric anhydride followed by elaboration of the acid moiety to the requisite β-keto phosphorane. Using this route, kilogram quantities of the desired drug candidate were prepared.
- Keen, Stephen P.,Cowden, Cameron J.,Bishop, Brian C.,Brands, Karel M. J.,Davies, Antony J.,Dolling, Ulf H.,Lieberman, David R.,Stewart, Gavin W.
-
p. 1771 - 1779
(2007/10/03)
-
- Radical [n + 1] annulations with sulfur dioxide
-
A new methodology for [n + 1] radical annulation using sulfur dioxide as a geminal radical acceptor/donor is presented. This methodology provides a novel route to the formation of five-, six-, and seven-membered cyclic sulfones utilizing a radical chain m
- Tsimelzon, Anna,Braslau, Rebecca
-
p. 10854 - 10859
(2007/10/03)
-
- Radical cyclizations of alkenyl acylphosphonate derivatives under thermal and photochemical conditions
-
The use of alkenyl acylphosphonate and acylphosphine oxide derivatives as acceptors in radical cyclizations was studied under thermal and photochemical conditions, respectively. The cyclizations of alkenyl acylphosphonates under thermal conditions occurre
- Cho, Chang Ho,Kim, Sunggak,Yamane, Motoki,Miyauchi, Hironori,Narasaka, Koichi
-
p. 1665 - 1672
(2007/10/03)
-
- Enantioselective Total Syntheses of (+)-Arborescidine A, (-)-Arborescidine B, and (-)-Arborescidine C
-
Described are the first enantioselective total syntheses of (+)-arborescidine A ((+)-1), (-)-arborescidine B ((-)-2), and (-)-arborescidine C ((-)-3), via routes that proceeded in five steps and 50% overall yield, eight steps and 61% overall yield, and ni
- Santos, Leonardo S.,Pilli, Ronaldo A.,Rawal, Viresh H.
-
p. 1283 - 1289
(2007/10/03)
-
- An intramolecular organocatalytic cyclopropanation reaction
-
Nucleophilic tertiary amines catalyze an intramolecular cyclopropanation reaction to give [n.1.0]bicycloalkanes in good yield (see scheme). The reaction is tolerant of a wide range of functional groups and is highly diastereoselective. Furthermore, when a
- Bremeyer, Nadine,Smith, Stephen C.,Ley, Steven V.,Gaunt, Matthew J.
-
p. 2681 - 2684
(2007/10/03)
-
- A concise asymmetric synthesis of the ADE fragment of nakadomarin A
-
(Chemical equation presented) The ADE fragment of nakadomarin A has been synthesized in nine linear steps from commercial material. The key transformation is an asymmetric azomethine ylide [1,3]-dipolar cycloaddition to establish the AD-spirocyclic system containing three of the four stereocenters of the natural product.
- Ahrendt, Kateri A.,Williams, Robert M.
-
p. 4539 - 4541
(2007/10/03)
-
- The extraordinary reactions of phenyldimethylsilyllithium with N,N-disubstituted amides
-
The reactions of the silyllithium reagent with tertiary amides was discussed. The enediamines were easily isomerized from cis to trans, easily oxidized to dienediamines and were hydrolyzed to α-aminoketones. If the two equivalents of the silyllithium reagent were used, the product was an α-silylamine. The results show that each member of the homologous series of amides gives rise to a substantially different product.
- Buswell, Marina,Fleming, Ian,Ghosh, Usha,Mack, Stephen,Russell, Matthew,Clark, Barry P.
-
p. 3006 - 3017
(2007/10/03)
-
- A stereoselective synthesis of five- and six-membered cyclic β-amino acids
-
The cyclic β-amino acids 1 and 2 have been prepared in a short and stereoselective manner. The synthesis features a diastereoselective thioester enolate/imine condensation reaction and a ring-closing metathesis as key processes. Wiley-VCH Verlag GmbH & Co
- Perlmutter, Patrick,Rose, Mark,Vounatsos, Filisaty
-
p. 756 - 760
(2007/10/03)
-
- Enantioselective total syntheses of manzamine A and related alkaloids
-
As a prelude to undertaking the total syntheses of the complex manzamine alkaloids, a series of model studies were conducted to establish the scope and limitations of intramolecular [4 + 2] cycloadditions of N-acylated vinylogous ureas with the trienic substrates 17a,b, 28a,b, and 34. These experiments clearly demonstrated that the geometry of the internal double bond and the presence of an electron-withdrawing group on the diene moiety were essential for the facile and stereoselective formation of the desired cycloadducts. The enantioselective syntheses of the manzamine alkaloids ircinol A (75), ircinal A (5), and manzamine A (1) were then completed by employing a convergent strategy that featured a novel domino Stille/Diels-Alder reaction to construct the tricyclic ABC ring core embodied in these alkaloids. Thus, the readily accessible chiral dihydropyrrole 58 was first converted in a single chemical operation into the key tricyclic intermediate 60. Two ring-closing metathesis reactions were then used to form the 13- and 8-membered rings leading to Z-72 and 74, the latter of which was quickly elaborated into ircinal A (5) via ircinol A (75). The synthetic 5 thus obtained was converted into manzamine A (1) following literature precedent. This concise synthesis of ircinal A required a total of 24 operations from commercially available starting materials with the longest linear sequence being 21 steps.
- Humphrey, John M.,Liao, Yusheng,Ali, Amjad,Rein, Tobias,Wong, Yue-Ling,Chen, Hui-Ju,Courtney, Anne K.,Martin, Stephen F.
-
p. 8584 - 8592
(2007/10/03)
-
- The first successful base-promoted isomerization of propargyl amides to chiral ynamides. Applications in ring-closing metathesis of ene-ynamides and tandem RCM of diene-ynamides
-
(Matrix Presented) A highly useful sequence of reactions is described here. These reactions consist of the first successful base-induced isomerizations of propargyl amides to chiral ynamides, applications of these novel ynamides in ring-closure metathesis
- Huang, Jian,Xiong, Hui,Hsung, Richard P.,Rameshkumar,Mulder, Jason A.,Grebe, Tyler P.
-
p. 2417 - 2420
(2007/10/03)
-
- Ru3(CO)12-Catalyzed intermolecular cyclocoupling of ketones, alkenes or alkynes, and carbon monoxide. [2 + 2 + 1] Cycloaddition strategy for the synthesis of functionalized γ-butyrolactones
-
The ruthenium-catalyzed intermolecular cyclocoupling of ketones (or aldehydes), alkenes (or alkynes), and CO, which leads to γ-butyrolactones, is described. The reaction represents the first example of the catalytic synthesis of heterocycles via an interm
- Tobisu,Chatani,Asaumi,Amako,Ie,Fukumoto,Murai
-
p. 12663 - 12674
(2007/10/03)
-
- Gas phase and condensed phase SNi reactions. The competitive six and seven centre cyclisations of the 5,6-epoxyhexoxide anion. A joint experimental and ab initio study. A comparison with SNi reactions of homologous epoxyalkoxide anions
-
A. Ab initio calculations [at the MP2 Fc/6-31+G(d) level of theory] indicate that the barriers to the transition states for the competitive six and seven centre SNi cyclisation processes of the 5,6-epoxyhexoxide anion are 35.0 and 39.7 kJ mol-1 respectively. Experimental studies show that (i) in solution, the 5,6-epoxyhexoxide anion cyclises (and at the same time opens the ethylene oxide ring) to give tetrahydropyran-2-methanol as the predominant product on workup, and (ii) collisional activation of the 5,6-epoxyhexoxide anion in the gas phase gives the 2-tetrahydropyranmethoxide anion as the exclusive anionic product. It is proposed that frequency factors (Arrhenius A factors) control the courses of these kinetically controlled gas phase reactions. A comparison of the calculated harmonic vibrational partition functions for the two possible transition states confirms a higher value of QVib for the reaction proceeding through the six-membered transition state. B. A comparison is made of the reported competitive SNi reactions for 2,3-epoxypropoxide, 3,4-epoxybutoxide, 4,5-epoxypentoxide and 5,6-epoxyhexoxide anions. For all but the 3,4-epoxybutoxide system, the exclusive or major product is that which contains the smaller of the two ring systems for both gas phase and condensed phase reactions. In the case of the 3,4-epoxybutoxide system: (i) in the gas phase, both four and five membered ring SNi products are formed in comparable yield, and (ii) in the condensed phase, the major product is that with the larger ring.
- Hevko, John M.,Dua, Suresh,Bowie, John H.,Taylor, Mark S.
-
p. 457 - 464
(2007/10/03)
-
- Fibrinogen receptor antagonists
-
Fibrinogen receptor antagonists having the structure, for example, of STR1 for example STR2
- -
-
-
- Radical Translocation Reactions across Amides. 1,5-Hydrogen-Transfer Reactions of o-Iodobenzamides and N-(o-Iodobenzyl) Amides
-
Radicals derived from N,N-disubstituted o-iodobenzamides undergo rapid 1,5-hydrogen-transfer reactions.The regioselectivity of these reactions is coupled to the rotamer population of the starting iodobenzamide, and the products vary with changing amide substituents.Related 1,5-hydrogen-transfer reactions are observed for N-alkyl-N-(o-iodobenzyl)-benzamides and -acetamides.
- Curran, Dennis P.,Liu, Hohgtao
-
p. 1377 - 1394
(2007/10/02)
-
- Generation of Acyl Radicals from 2-Naphthyl Thioesters
-
A series of S-2-naphthyl thioesters were synthesized from the corresponding carboxylic acids or acid chlorides.Irradiation of these thioesters in the presence of a hydrogen source (i.e., 1,4-cyclohexadiene) generated the corresponding aldehydes.In this fashion, primary, secondary, tertiary, and aryl carboxylic acids were converted to the aldehydes in high yields.Intramolecular radical cyclization reactions support the hypothesis that the reaction proceeds via the formation of acyl radicals.The formation of aldehydes was not perturbed by possible Norrish Type II reactions.
- Penn, John H.,Liu, Fang
-
p. 2608 - 2612
(2007/10/02)
-
- N-hydroxypyridine-2-thione carbamates. V. Syntheses of alkaloid skeletons by aminium cation radical cyclizations
-
The title radical precursors (PTOC carbamates) were employed as sources of a variety of 5,6-unsaturated aminium cation radicals. 5-Exo radical cyclization followed by trapping by t-BuSH or the PTOC carbamate gave a variety of aklaloid skeletons, typically in good to excellent yields, including pyrrolidines, perhydroindoles, pyrrolizidines, tropanes, 9-azabicyclo[4.2.1]nonanes, 6-azabicyclo [3.2.1]octanes. 6-Exo and 7-endo cyclizations competed in a 6,7-unsaturated system.
- Newcomb, Martin,Marquardt, Donald J.,Deeb, Thomas M.
-
p. 2329 - 2344
(2007/10/02)
-
- Synthesis and Reactions of Iodo Lactams
-
The synthesis of a series of iodo lactams has been achieved by a new cyclization method that depends on generating N,O-bis(trimethylsilyl)imidate derivatives as intermediates.Treatment of an unsaturated amide with trimethylsilyl triflate in pentane and then iodine in tetrahydrofuran gives the iodo lactam.Some reactions of this new difunctional group with bases, nucleophiles, and Michael acceptors leading to functionalized or elaborated lactams are presented.In general, iodo lactams undergo direct SN2 reactions with reactive (but weakly basic) nucleophiles like azide and triphenylphosphine and elimination or decomposition in the presence of bases or basic nucleophiles.Sodium hydride may be used to generate an N-acylaziridine intermediate, which can be opened with azide to deliver an azido lactam with overall retention of stereochemistry.Silver-assisted solvolysis of iodo lactams gives the hydroxy lactams with retention of configuration, probably also because of participation by the lactam nitrogen.The sodium salt of 5-(iodomethyl)-2-pyrrolidinone (3), generated at -20 deg C, undergoes an annulation reaction with unsaturated esters (but not sulfones), leading to pyrrolizidine derivatives.
- Knapp, Spencer,Levorse, Anthony T.
-
p. 4006 - 4014
(2007/10/02)
-