- Copper-Catalyzed Tandem Cross-Coupling and Alkynylogous Aldol Reaction: Access to Chiral Exocyclic α-Allenols
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An enantioselective copper-catalyzed tandem cross-coupling/alkynylogous aldol reaction has been developed. The tetrasubstituted allenoates containing both central and axial chirality have been obtained in moderate to good yields and excellent enantio-and
- Xu, Guangyang,Wang, Zhen,Shao, Ying,Sun, Jiangtao
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supporting information
p. 5175 - 5179
(2021/07/19)
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- Mechanistic Interrogation of Alkyne Hydroarylations Catalyzed by Highly Reduced, Single-Component Cobalt Complexes
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Highly reactive catalysts for ortho-hydroarylations of alkynes have previously been reported to result from activation of CoBr2 by Grignard reagents, but the operative mechanism and identity of the active cobalt species have been undefined. A mechanistic analysis of a related system, involving hydroarylations of a (N-aryl)aryl ethanimine with diphenylacetylene, was performed using isolable reduced Co complexes. Studies of the stoichiometric reaction of Co(I) or Co(II) precursors with CyMgCl implicated catalyst initiation via a β-H elimination/deprotonation pathway. The resulting single-component Co(-I) complex is proposed as the direct pre-catalyst. Michaelis-Menten enzyme kinetic studies provide mechanistic details regarding the catalytic dependence on substrate. The (N-aryl)aryl ethanimine substrate exhibited saturation-like behavior, whereas alkyne demonstrated a complex dependency; rate inhibition and promotion depend on the relative concentration of alkyne to imine. Activation of the aryl C-H bond occurred only in the presence of coordinated alkyne, which suggests operation of a concerted metalation-deprotonation (CMD) mechanism. Small primary isotope effects are consistent with a rate-determining C-H cleavage. Off-cycle olefin isomerization catalyzed by the same Co(-I) active species appears to be responsible for the observed Z-selectivity.
- Suslick, Benjamin A.,Tilley, T. Don
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supporting information
p. 11203 - 11218
(2020/07/08)
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- Hydroxylamine-O-Sulfonic Acid (HOSA) as a Redox-Neutral Directing Group: Rhodium Catalyzed, Additive Free, One-Pot Synthesis of Isoquinolines from Arylketones
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A new application of hydroxylamine-O-sulfonic acid (HOSA) has been discovered whereby aromatic ketones react with HOSA and alkynes to form isoquinolines in the presence of a RhIII catalyst. This C–H/N–O annulation methodology gives excellent yields even without any silver additive, acid/base or metal oxidant. This is the first report wherein a directing group is simultaneously forming in situ, acting as acid additive, and also as an internal oxidant.
- Biswal, Pragati,Pati, Bedadyuti Vedvyas,Chebolu, Rajesh,Ghosh, Asit,Ravikumar
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supporting information
p. 1006 - 1014
(2020/02/15)
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- Structural Dynamics and Stereoselectivity of Chiral Benzylideneamine N,C-Chelate Borane Photo–Thermal Isomerization
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New chiral N,C-chelate organoboron compounds based on benzylideneamines (bza) with the general formula of B(bza-R)Mes2 (R=H or Me; Mes=mesityl) are reported. A chiral substituent group R- or S-CH(CH3)Ph (Ph=phenyl) was introduced to
- Li, Haijun,Novoseltseva, Polina,Sauriol, Francoise,Wang, Suning,Wang, Xiang
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supporting information
(2020/02/11)
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- Chemo- and Stereoselective Synthesis of Fluorinated Amino Alcohols through One-pot Reactions using Alcohol Dehydrogenases and Amine Transaminases
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A series of amino alcohols have been prepared in a chemo-, diastereo- and enantioselective fashion starting from the corresponding (het)aryl diketones, avoiding tedious chemical protection and deprotection steps. Different alcohol dehydrogenases have been
- González-Martínez, Daniel,Gotor, Vicente,Gotor-Fernández, Vicente
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supporting information
p. 5398 - 5410
(2020/10/06)
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- Internal B-O Bond-Facilitated Photoisomerization of Boranes: Ring Expansion Versus Oxyborane Elimination/Intramolecular Diels-Alder Addition
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Boron compounds (1-4) containing an internal B-O bond have been found to undergo facile multistructural transformations upon irradiation at 365 or 410 nm, generating rare 8-membered B,O-heterocycles (1c-4c). In addition, 2 and 3 also undergo an intramolecular Diels-Alder addition and oxyborane elimination concomitantly, via intermediates 2b/3b, producing 2d/3d. The pathways to isomer c and product d were found to be a thermal process and a photo process, respectively.
- Hu, Guo-Fei,Li, Hai-Jun,Zeng, Chao,Wang, Xiang,Wang, Nan,Peng, Tai,Wang, Suning
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supporting information
p. 5285 - 5289
(2019/09/03)
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- Synthesis of the Tetracyclic Cores of the Integrastatins, Epicoccolide A and Epicocconigrone A
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The integrastatins, epicoccolide A and epicoccongirone A, are natural products containing a unique [6.6.6.6]-tetracyclic core framework that exhibit a broad spectrum of biological activities. A synthesis of the common core of epicoccolide A and epicocconigrone A has been achieved using an umpolung alkylation-lactonization to assemble an isochromanone from which the bridged 1,3-dioxane was readily assembled. A different strategy was required to access the core on the integrastatins; an initial aryllithium addition to an aldehyde, followed by oxidation and treatment of the masked dihydroxyketone with acid gave the desired core structure.
- Jeong, Joo Young,Sperry, Jonathan,Brimble, Margaret A.
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p. 11935 - 11944
(2019/09/30)
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- Rhodium-catalyzed C–H activation/cyclization of enaminones with sulfoxonium ylides toward polysubstituted naphthalenes
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A rhodium-catalyzed ortho-C–H functionalization and annulation between enaminones and sulfoxonium ylides was developed, affording a series of multi-substituted naphthalenes in good to moderate yields with excellent functional group compatibility. The proc
- Wang, Zhenlian,Xu, Huang
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supporting information
p. 664 - 667
(2019/02/06)
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- Diacetal Ditellurides as Highly Active and Selective Antiparasitic Agents toward Leishmania amazonensis
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Leishmaniasis is a neglected tropical disease and a public health concern in at least 98 countries, affecting mainly the poorest populations. Pharmaceuticals and chemotherapies available for leishmaniasis treatment have several limitations, which clearly justify the efforts to find new potential antileishmanial drugs. In this context, antiprotozoal activities toward different Leishmania species have been reported for hypervalent tellurium compounds, which motivated us to investigate, for the first time, the leishmanicidal properties of some nonhypervalent diaryl ditellurides. Thus, this work describes in vitro activity against Leishmania amazonensis and the cytotoxicities of diaryl ditellurides. Ditelluride LQ7 revealed a strong leishmanicidal activity on promastigotes and amastigotes at submicromolar levels (IC50 = 0.9 ± 0.1 and 0.5 ± 0.1 μmol L-1, respectively) and presented selectivity indexes greater than those of reference drug miltefosine. This preliminary study suggests that diaryl ditellurides may be promising scaffolds for the development of new agents for leishmaniasis treatment.
- Bandeira, Pamela T.,Souza, Jo?o Pedro A.,Scariot, Débora B.,Garcia, Francielle P.,Nakamura, Celso V.,De Oliveira, Alfredo R. M.,Piovan, Leandro
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supporting information
p. 806 - 810
(2019/05/06)
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- Straightforward microwave-assisted synthesis of organochalcogen amines by reductive amination
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Organoselenium and organotellurium amines have been shown to present a broad range of interesting properties for both synthetic and biological applications. Despite the current interest in this class of compounds, only few methods to access organochalcogen amines are described in literature, most which involve restrictive conditions associated with displacement reaction, metal-assisted reactions or enzymatic approach. In general, these methods produce organochalcogen amines in poor yields, by long reactions that require protective groups. In this regard, a set of aryl chalcogen (Se, Te) amines were prepared by reductive amination employing a microwave-assisted one-pot protocol. This approach offered a convenient and versatile method to synthesize primary and secondary organochalcogen amines with significantly short time reactions (5–10 min) and satisfactory yields (40–89%).
- Dalmolin, Mara C.,Bandeira, Pamela T.,Ferri, Matheus S.,de Oliveira, Alfredo R.M.,Piovan, Leandro
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- Manganese(I)-Catalyzed Substitutive C?H Allylation
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The first manganese(I)-catalyzed C?H allylations with ample scope were achieved by carboxylate assistance. The highly selective C?H/C?O functionalizations proved viable with densely substituted allyl carbonates, and the organometallic C?H allylation strategy set the stage for expedient late-stage diversification with excellent levels of positional selectivity.
- Liu, Weiping,Richter, Sven C.,Zhang, Yujiao,Ackermann, Lutz
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supporting information
p. 7747 - 7750
(2016/07/07)
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- Easy Access to 1-Amino and 1-Carbon Substituted Isoquinolines via Cobalt-Catalyzed C - H/N - O Bond Activation
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A green atom-economical method for the synthesis of highly functionalized 1-amino and 1-carbon substituted isoquinolines from the reaction of N′-hydroxybenzimidamides and aryl ketoximes, respectively, with alkynes via pentamethylcyclopentadienylcobalt(III)-catalyzed C - H/N - O bond activation is described. The external oxidant-free annulation reaction uses the =NOH moiety in N′-hydroxybenzimidamides or N-aromatic ketone oximes as the directing group and internal oxidant. This first row transition metal-catalyzed annulation serves as an efficient alternative for the synthesis of isoquinolines, as water is the only by-product and expensive noble metals such as rhodium(III), iridium(III), palladium(II), and ruthenium(II) are not required. The reaction proceeds via C - H activation, alkyne insertion, reductive elimination, and N - O activation.
- Muralirajan, Krishnamoorthy,Kuppusamy, Ramajayam,Prakash, Sekar,Cheng, Chien-Hong
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supporting information
p. 774 - 783
(2016/03/09)
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- Rhodium-Catalyzed Cyclocarbonylation of Ketimines via C-H Bond Activation
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A novel rhodium-catalyzed oxidative cyclocarbonylation of ketimines via cleavage of two C-H bonds was established, which provided a direct and reliable method for the synthesis of a wide range of 3-methyleneisoindolin-1-ones with mostly moderate yields. P
- Gao, Bao,Liu, Song,Lan, Yu,Huang, Hanmin
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supporting information
p. 1480 - 1487
(2016/06/09)
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- Manganese-catalyzed synthesis of cis-β-amino acid esters through organometallic C-H activation of ketimines
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Manganese-catalyzed C-H functionalization reactions of ketimines set the stage for the expedient synthesis of cis-β-amino acid esters through site- and regioselective alkene annulations. The organometallic C-H activation occurred efficiently with high fun
- Liu, Weiping,Zell, Daniel,John, Michael,Ackermann, Lutz
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supporting information
p. 4092 - 4096
(2015/03/30)
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- Cobalt(III)-Catalyzed C-H/N-O Functionalizations: Isohypsic Access to Isoquinolines
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C-H/N-O functionalizations by cobalt(III) catalysis allowed the expedient synthesis of a broad range of isoquinolines. Thus, internal and challenging terminal alkynes proved to be viable substrates for an isohypsic annulation, which was shown to proceed by a facile C-H cobaltation.
- Wang, Hui,Koeller, Julian,Liu, Weiping,Ackermann, Lutz
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supporting information
p. 15525 - 15528
(2015/11/03)
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- New methods for the synthesis of naphthyl amines; Application to the synthesis of dihydrosanguinarine, sanguinarine, oxysanguinarine and (±)-maclekarpines B and C
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A new method for preparing naphthyl amines from 1,5 unsaturated dicarbonyl precursors is described; the utility of this new method was proven in the syntheses of several natural products, all containing the benzo[c]phenanthridine core and enabled by a radical promoted cyclisation of the naphthyl amine products formed in the key cyclisation. the Partner Organisations 2014.
- Tatton, Matthew R.,Simpson, Iain,Donohoe, Timothy J.
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supporting information
p. 11314 - 11316
(2014/11/07)
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- Cobalt-catalyzed enantioselective intramolecular hydroacylation of ketones and olefins
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Cobalt-chiral diphoshine catalytic systems promote intramolecular hydroacylation reactions of 2-acylbenzaldehydes and 2-alkenylbenzaldehydes to afford phthalide and indanone derivatives, respectively, in moderate to good yields with high enantioselectivities. The ketone hydroacylation did not exhibit a significant H/D kinetic isotope effect (KIE) with respect to the aldehyde C-H bond, indicating that C-H activation would not be involved in the rate-limiting step.
- Yang, Junfeng,Yoshikai, Naohiko
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supporting information
p. 16748 - 16751
(2015/02/05)
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- Modular isoquinoline synthesis using catalytic enolate arylation and in situ functionalization
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A methyl ketone, an aryl bromide, an electrophile, and ammonium chloride were combined in a four-component, three-step, and one-pot coupling procedure to furnish substituted isoquinolines in overall yields of up to 80%. This protocol utilizes the palladiu
- Pilgrim, Ben S.,Gatland, Alice E.,McTernan, Charlie T.,Procopiou, Panayiotis A.,Donohoe, Timothy J.
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supporting information
p. 6190 - 6193
(2014/01/17)
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- The first stereoselective Pd-catalyzed addition of boronic acids onto aldehydes
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The coupling reaction between 2-p-tolylsulfinyl benzaldehyde and substituted boronic acids catalyzed by Pd2(dba)3·CHCl3 proceeds in a stereoselective manner, demonstrating the efficiency of the sulfinyl group as a chiral i
- Novodomska, Alexandra,Dudicova, Maria,Leroux, Frederic R.,Colobert, Francoise
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p. 1628 - 1634
(2008/02/11)
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- Chemo- and enantioselective routes to chiral fluorinated hydroxyketones using ketoreductases
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Chiral fluorinated hydroxyketones were synthesized with excellent ee (>98%) and yield by a chemo- and stereoselective reduction of prochiral methyl/trifluoromethyl diketones using commercially available ketoreductase enzymes. By using p- and m-trifluoroac
- Grau, Brendan T.,Devine, Paul N.,DiMichele, Lisa N.,Kosjek, Birgit
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p. 4951 - 4954
(2008/03/28)
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- Novel phosphine ligands bearing 3(5)-pyrazolyl and 4-(2-amino)pyrimidinyl groups: Synthesis and coordination chemistry
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Novel triphenyl phosphine ligands bearing pyrazole or 2-aminopyrimidine groups in the ortho or meta position of one or three of the phenyl rings were obtained starting from the corresponding acyl derivatives Ph2P(o- C6H4-C
- Sun, Yu,Hienzsch, Antje,Grasser, Jens,Herdtweck, Eberhardt,Thiel, Werner R.
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p. 291 - 298
(2007/10/03)
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- Preparation of chiral organochalcogeno-α-methylbenzyl alcohols via biocatalysis. The role of Daucus carota root
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A series of organochalcogeno acetophenones 3 has been submitted to the action of enzymes from Daucus carota root. Some of the chalcogeno ketones tested afforded the chiral organochalcogeno-α-methylbenzyl alcohols 4 in excellent enantiomeric excesses (>99%), under mild and environmentally friendly conditions. The stereoselectivity of the reduction is in accordance with Prelog's rule. Enzymatic kinetic resolution as alternative process was used to obtain the chiral ortho-organochalcogeno-α-methylbenzyl alcohols in excellent enantiomeric excess (>99%).
- Comasseto, Jo?o V.,Omori, álvaro T.,Porto, André L. M.,Andrade, Leandro H.
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p. 473 - 476
(2007/10/03)
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- 1-[2-(2-Hydroxyalkyl)phenyl]ethanone: A New Photoremovable Protecting Group for Carboxylic Acids
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(Equation presented) A new photoremovable protecting group for carboxylic acids is introduced. The protecting group 1-[2-(2-hydroxyalkyl)phenyl]ethanone, HAPE, is used to protect various carboxylic acids. When photolyzed, the protected compound releases the acid in 70-85% isolated yields. The synthesis and the results of photorelease of the protected acids are presented here.
- Atemnkeng, Walters N.,Louisiana II, Larry D.,Yong, Promise K.,Vottero, Breanne,Banerjee, Anamitro
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p. 4469 - 4471
(2007/10/03)
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- Synthesis, structure and spectroscopic characteristics of 2′-boryl-4′-dimethylaminochalcones. Effect of an intramolecular boron-oxygen coordinate bond to the conjugated system
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2′-Diethylboryl-4″-dimethylaminochalcone (1) and the related compounds (4)-(7) bearing a dioxyboryl group in the 2′-position were synthesized, and the effect of the intramolecular boron-oxygen coordinate bond on the spectroscopic characteristics of 4″-dimethylaminochalcone chromophore was examined by comparison with 4″-dimethylaminochalcone (2) using UV/VIS and fluorescence spectra.
- Murafuji, Toshihiro,Sugimoto, Kenji,Yanagimoto, Sachiko,Moriya, Tomokazu,Sugihara, Yoshikazu,Mikata, Yuji,Kato, Masako,Yano, Shigenobu
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p. 929 - 942
(2007/10/03)
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- Synthesis of a stable mimic for the ring closed form of gallein, featuring a novel one pot boron tribromide mediated intramolecular cyclisation process
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Treatment of 9-{2-[1-(1,3-dioxalan-2-yl)ethyl]phenyl}-3,4,5,6-tetrabenzyloxy-9H-xanthen-9-o l 14 with excess boron tribromide at -78°C, and warming to room temperature, provides a facile route to 3,4,5,6-tetrahydroxy-spiro(1H-indene-1,9-[9H]-xanthene-3-(2
- Crew, Andrew P. A.,Lyons, Amanda J.,Camp, Nicholas P.
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p. 1133 - 1135
(2007/10/03)
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- A General SRN1-Based Method for Total Synthesis of Unsymmetrically Hydroxylated 2,2'-Binaphtalenes
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An SRN1 reaction between 2'-haloacetophenones and 2'-acetonaphthone derived enolates is the key step in a straightforward one-pot synthesis of unsymetrically substituted 2,2'-binaphtyl derivatives 3a-j.
- Beugelmans, Rene,Bois-Choussy, Michele,Tang, Qian
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p. 3880 - 3883
(2007/10/02)
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