- CARBENE LIGANDS AS ANTHRACYCLINONESYNTHONS-II CHROMIUM MEDIATED CYCLOADDITION OF ALKYNES, CARBENES AND CARBON MONOXIDE: APPLICATION TO RING B SYNTHESIS IN ANTHRACYCLINONES
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The cycloaddition of Cr-co-ordinated alkyne, carbene and carbonyl ligands provides a variable route to the anthracyclinone skeleton.The key step of a formal total synthesis of 4-demethoxydaunomycinone (1) is based on the reaction of carbonyl-carbene complex 15 -used as a CD ring synthon- and alkyne 9 leading to the formation of ring B.
- Doetz, Karl Heinz,Popall, Michael
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- A chemical probe for lysine malonylation
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Tag! You′re it! MalAM-yne is a chemical reporter for malonylation of lysines within proteins (see scheme), a newly identified posttranslational modification. MalAM-yne is cell-permeable and metabolically incorporated into proteins in living cells. Subsequent bioorthogonal tag conjugation allows the fluorescent visualization of cellular malonylation and profiling of malonylated proteins. Copyright
- Bao, Xiucong,Zhao, Qian,Yang, Tangpo,Fung, Yi Man Eva,Li, Xiang David
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- Silver oxide(I) promoted Conia-ene/radical cyclization for a straightforward access to furan derivatives
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A novel access to fused furan cores using silver oxide(I) has been developed. Mechanistic investigations indicate the involvement of a Conia-ene reaction/radical cyclization for an expedient path to complex furan derivatives. The reaction is broad in scop
- Ardisson, Janick,Lannou, Marie-Isabelle,Mohamed, Selkti,Sorin, Geoffroy,Yu, Bao
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supporting information
p. 1374 - 1377
(2022/02/11)
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- Iron-Catalyzed [2+2+2] Annulation of Aliphatic Bridged 1,n-Enynes with Aldehydes for the Synthesis of Fused Pyrans
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An iron-catalyzed [2+2+2] annulation of aliphatic bridged 1,n-enynes with aldehydes was developed. Aldehydes play a dual role as the precursors of acyl radicals to trigger the cascade cyclization but also as the radical acceptors to terminate the annulation. This two-in-one strategy overcomes the limitation in [2+2+m] cyclization that requires a rigid benzene skeleton as the essential linker, thus enabling the efficient synthesis of functionalized fused [5.6] and [6.6] pyran skeletons.
- Tian, Tian,Wang, Xin,Lv, Leiyang,Li, Zhiping
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supporting information
p. 4425 - 4428
(2020/06/05)
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- Visible-Light Mediated Hydrosilylative and Hydrophosphorylative Cyclizations of Enynes and Dienes
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Described herein is a visible-light mediated intermolecular radical cyclization approach to access heterocycles. Heteroatom radicals, such as silicon and phosphorus atom radicals, were generated via direct hydrogen atom abstraction by the photoexcited catalyst species with hydro-silanes and phosphine oxides. The radical addition/cyclization/HAT (hydrogen atom transfer) reaction sequences of 1,6-enynes and 1,6-dienes were highly efficient delivering the desired heterocycles in good yields.
- Chen, Xiaoyun,Hou, Hong,Shi, Yaocheng,Xu, Yue,Yan, Chaoguo,Yang, Haibo,Zhu, Shaoqun
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supporting information
(2020/03/04)
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- SUBSTITUTED HETEROCYCLES AS c-MYC TARGETING AGENTS
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Disclosed are substituted heterocycle compounds including substituted pyrazoles, substituted pyrimidines, and substitute triazoles. The substituted heterocycles disclosed herein are shown to be useful in inhibiting c-MYC and may be utilized as therapeutics for treating cancer and cell proliferative disorders.
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Paragraph 0400; 0403-0404
(2020/12/25)
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- Enantioselective α-Amination of Acyclic 1,3-Dicarbonyls Catalyzed by N-Heterocyclic Carbene
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Herein, we describe a method for the catalytic enantioselective α-amination of α-substituted acyclic 1,3-ketoamides and 1,3-amidoesters that affords the products possessing N-substituted quaternary stereocenters with a chiral N-heterocyclic carbene (NHC). The reaction is based on the utilization of an intrinsic Br?nsted base characteristic of NHC that enables the catalytic formation of a chiral ion pair comprising the enolate and the azolium ion. A series of challenging open-chain α-substituted 1,3-dicarbonyls are aminated via this method with ee's of ≤99%.
- Santra, Surojit,Maji, Ujjwal,Guin, Joyram
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supporting information
p. 468 - 473
(2020/02/04)
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- Complementary Reactivity of 1,6-Enynes with All-Metal Aromatic Trinuclear Complexes and Carboxylic Acids
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The distinct reactivity of 1,6-enynes in the presence of a trinuclear metal complex activated by a carboxylic acid is presented. The triplatinum catalyst enables the cyclization of the substrate and subsequent incorporation of a nucleophile in the final product. In contrast, sequential cyclization/double bond shift occurs under analogous conditions in the presence of the corresponding tripalladium complex.
- Cecchini, Chiara,Lanzi, Matteo,Cera, Gianpiero,Malacria, Max,Maestri, Giovanni
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supporting information
p. 1216 - 1224
(2019/02/26)
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- Au-Cavitand Catalyzed Alkyne-Acid Cyclizations
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Supramolecular cavitands that contain inwardly directed functional groups have yielded specialized transformations and trapping of reactive intermediates. A recently reported 3-wall Au cavitand provides exciting opportunities for supramolecular catalysis. In this study, a variety of substituted γ-alkynoic acids were reacted to give lactones. The interaction of peripheral “R” groups revealed differential catalyst behavior. Extremely large and small groups reacted with appreciable rate. Intermediate sized groups however, slowed significantly: giving support that size-specific binding is at play when using cavitands as a scaffold for gold catalysis. These results serve as some of the first evidence of the interplay between substrate and cavitand interior in the catalytic sphere.
- Ho, Tam D.,Schramm, Michael P.
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supporting information
p. 5678 - 5684
(2019/08/21)
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- Cobalt-catalyzed versus uncatalyzed intramolecular Diels-Alder cycloadditions
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The intramolecular [4+2] cycloadditions of dienynes was investigated using cobalt-based catalysts. Substrates without substitution on alkyne moiety were found to react under thermal activation. The use of a cobalt salt as catalyst made reactions cleaner by limiting the formation of byproducts. Cycloadditions with dienynes possessing a substituent on the alkyne pattern occurred only in presence of a cobalt catalyst which displayed a moderate to good activity depending on the substrate patterns.
- Biletskyi, Bohdan,Tenaglia, Alphonse,Clavier, Hervé
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supporting information
p. 103 - 107
(2017/12/28)
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- Copper-Mediated Nucleophilic Addition/Cascade Cyclization of Aryl Diynes
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Treatment of diyne substrates with sulfinate salts under the action of copper(II) triflate results in a cascade cyclization reaction. The reaction involves nucleophilic addition of the sulfinate and formation of two new C-C bonds with concomitant cleavage of an aryl C-H bond. The reaction proceeds in good yields with a range of diyne precursors and sulfinate salts. Preliminary mechanistic analysis reveals a rare example of an operative ionic mechanism in contrast to other related cyclizations.
- Sinclair, Geoffrey S.,Yang, Tianyu,Wang, Sunmeng,Chen, Wei H.,Schipper, Derek J.
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supporting information
p. 802 - 805
(2017/03/01)
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- Lewis Acid-Catalyzed Intramolecular [3+2] Cross-Cycloaddition of Aziridine 2,2-Diesters with Conjugated Dienes for Construction of Aza-[n.2.1] Skeletons
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A novel Lewis acid-catalyzed [3+2] intramolecular cross-cycloaddition (IMCC) between aziridine 2,2-diesters and conjugated dienes has been developed. This is the first regiospecific IMCC of intramolecular 1,3-dipolar cycloadditions of azomethine ylides with carbon=carbon double bonds, and supplies a general and efficient strategy for construction of structurally complex and diverse aza-[n.2.1] skeletons. The [3+2]IMCC could be carried out under mild conditions and in gram scale. More importantly, 3-alkyl-substituted aziridines were also successful. The excellent structural diversity, the facile operation and the versatile post-modifications will support the applications of the [3+2]IMCC in natural products synthesis and drugs discovery.
- Zhan, Yizhou,Liu, Tao,Ren, Jun,Wang, Zhongwen
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supporting information
p. 17862 - 17866
(2017/11/27)
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- Silver-Catalyzed Cascade 1,6-Addition/Cyclization of para-Quinone Methides with Propargyl Malonates: An Approach to Spiro[4.5]deca-6,9-dien-8-ones
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An unprecedented silver-catalyzed cascade 1,6-addition/5-exo-dig cyclization reaction between para-quinone methides and propargyl malonates under mild reaction conditions has been described. This reaction provides an efficient method to construct versatile spiro[4.5]cyclohexadienones in moderate to excellent yields with high atom economy and scalability.
- Yuan, Zhenbo,Liu, Lina,Pan, Rui,Yao, Hequan,Lin, Aijun
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p. 8743 - 8751
(2017/08/23)
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- Rhodium-Catalyzed [5+2] Cycloaddition of 3-Acyloxy-1,4-enyne with Alkene or Allene
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We recently developed a completely new type of Rh-catalyzed [5+2] cycloaddition by using 3-acyloxy-1,4-enyne (ACE) as the 5-carbon building block. In this update, we show that ACE can undergo intramolecular [5+2] cycloaddition with either an alkene or an allene in the presence of an appropriate rhodium catalyst and ligands to afford bicyclic compounds with multiple stereogenic centers. In most cases, cis-fused bicyclo[5.3.0]decadienes are prepared highly diastereoselectively. (Figure presented.) .
- Song, Wangze,Lynch, John C.,Shu, Xing-Zhong,Tang, Weiping
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supporting information
p. 2007 - 2011
(2016/07/06)
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- Cyclization of alk-5-ynyl ketones promoted by Tf2NH and In(OTf)3: selective synthesis of 5- and 7-membered carbocycles
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Combined use of Tf2NH and In(OTf)3effectively promotes the cyclization of alk-5-ynyl ketones to cyclopent-1-enyl ketones at 30?°C. Single use of Tf2NH or In(OTf)3requires heating at 50?°C for efficient cyclizati
- Kinoshita, Hidenori,Miyama, Chika,Miura, Katsukiyo
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supporting information
p. 5065 - 5069
(2016/11/02)
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- A Ruthenium Complex-Catalyzed Cyclotrimerization of Halodiynes with Nitriles. Synthesis of 2- and 3-Halopyridines
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Monohalo- and dihalodiynes efficiently undergo [2+2+2] cyclotrimerization with nitriles in the presence of a catalytic amount of the ruthenium complex Cp*RuCl(cod) (10 mol%) to afford the corresponding halopyridines under ambient conditions in good isolated yields (up to 90%). The halopyridines are formed as two separable regioisomers. This is the first example of a direct synthesis of halopyridines from haloalkynes and nitriles. (Figure presented.) .
- Bedná?ová, Eva,Colacino, Evelina,Lamaty, Frédéric,Kotora, Martin
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supporting information
p. 1916 - 1923
(2016/07/06)
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- Rhodium(ii)-catalyzed intramolecular formal [4 + 3] cycloadditions of dienyltriazoles: Rapid access to fused 2,5-dihydroazepines
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Rhodium(ii)-catalyzed intramolecular [4 + 3] cycloadditions of dienyltriazoles have been developed, which enable the efficient synthesis of various fused 2,5-dihydroazepines. Mechanistically, the titled reaction proceeds via an interesting tandem cyclopropanation/aza-cope rearrangement.
- Tian, Yu,Wang, Yuanhao,Shang, Hai,Xu, Xudong,Tang, Yefeng
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supporting information
p. 612 - 619
(2015/02/05)
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- Domino Prins Cyclization of Enynols: Stereoselective Synthesis of Bicyclic Vinyl Fluorides
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A fluoride-induced termination of Prins cyclization has been observed using a tethered alkyne and stoichiometric amounts of AgSbF6 and found to generate a novel series of 6-fluoro-1-aryl-hexahydro-1H-isochromene derivatives in good yields with
- Venkateswarlu, Anipireddy,Kanakaraju, Marumudi.,Kunwar, Ajit C.,Rami Reddy, Yellala V.,Reddy, Basi V. S.
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supporting information
p. 5389 - 5392
(2015/08/24)
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- The synthesis of α-azidoesters and geminal triazides
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Three simple methods for the synthesis of geminal triazides are described: Starting from 1) 3-oxocarboxylic acids, 2) iodomethyl ketones, or 3) terminal olefins, a range of triazidomethyl ketones can be constructed under mild oxidative reaction conditions by the use of IBX-SO3K, a sulfonylated derivative of 2-iodoxybenzoic acid (IBX), and NaN3 as an azide source. This is the first report of representatives of this novel class of triazide compounds: Despite their high nitrogen content, the geminal triazides are easy to handle, even when preparative-scale syntheses are performed. (Caution: These procedures still require protective measures!) The triazides are now broadly available for further studies regarding their properties and reactivity. Furthermore, we show how the method can be used to provide α-azidoesters, which are potential building blocks for amino acids. Either/or: Geminal triazides are rapidly constructed with broad scope by the use of oxocarboxylic acids, iodomethyl ketones, or terminal olefins as starting substrates in oxidative azidations with a mild derivative of 2-iodoxybenzoic acid and sodium azide. Along with this little-studied class of organic azides, α-azidoesters were also synthesized.
- Klahn, Philipp,Erhardt, Hellmuth,Kotthaus, Andreas,Kirsch, Stefan F.
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supporting information
p. 7913 - 7917
(2014/08/05)
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- Iron(ii)-catalysed [2+2+2] cycloaddition for pyridine ring construction
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We report a new, simple and air-stable iron(ii) complex pre-catalyst for the synthesis of substituted pyridines via a [2+2+2] cycloaddition between diynes and nitrile derivatives. The Royal Society of Chemistry 2014.
- Richard, Vincent,Ipouck, Melinda,Merel, Delphine S.,Gaillard, Sylvain,Whitby, Richard J.,Witulski, Bernhard,Renaud, Jean-Luc
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supporting information
p. 593 - 595
(2014/01/06)
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- Ti-catalyzed straightforward synthesis of exocyclic allenes
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Exocyclic allenes constitute useful building blocks in organic synthesis and have recently been identified as key intermediates in the synthesis of natural products. Here the first general method for the most straightforward synthesis of exocyclic allenes
- Munoz-Bascon, Juan,Hernandez-Cervantes, Carmen,Padial, Natalia M.,Alvarez-Corral, Miriam,Rosales, Antonio,Rodriguez-Garcia, Ignacio,Oltra, J. Enrique
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supporting information
p. 801 - 810
(2014/01/23)
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- Cycloisomerization of acetylenic acids to γ-alkylidene lactones using a palladium(II) catalyst supported on amino-functionalized siliceous mesocellular foam
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Cycloisomerization of various γ-acetylenic acids to their corresponding γ-alkylidene lactones by the use of a heterogeneous Pd(II) catalyst supported on amino-functionalized siliceous mesocellular foam is described. Substrates containing terminal as well
- Nagendiran, Anuja,Verho, Oscar,Haller, Clemence,Johnston, Eric V.,Baeckvall, Jan-E.
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p. 1399 - 1405
(2014/03/21)
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- Increasing the efficiency of the transannular diels-alder strategy via palladium(II)-catalyzed macrocyclizations
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Palladium(II)-catalyzed macrocyclizations of bis(vinylboronate ester) compounds are demonstrated to provide a strategically efficient approach to transannular Diels-Alder reaction substrates. In several systems reported, the macrocycle is preorganized such that cycloaddition at room temperature occurs concomitantly with cyclization. Numerous advantages over palladium(0)-catalyzed cross-coupling approaches are demonstrated.
- Iafe, Robert G.,Kuo, Jonathan L.,Hochstatter, Dustin G.,Saga, Tomomi,Turner, Jonathan W.,Merlic, Craig A.
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supporting information
p. 582 - 585
(2013/04/10)
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- Base and copper(i) catalyzed Mannich, alkyne hydroamination cascades for the direct synthesis of 2-methylenepyrrolidines
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An efficient, simple-to-perform, one-pot reaction cascade to 2-methylenepyrrolidines from p-toluenesulfonyl protected imines and propargylated malonates under a combination of base and copper(i) catalysis is reported.
- Wang, Hai-Fei,Yang, Ting,Xu, Peng-Fei,Dixon, Darren J.
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supporting information; experimental part
p. 3916 - 3918
(2010/01/06)
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- Pd-catalyzed borylative cyclization of allenynes and enallenes
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Pd-catalyzed cyclization of 1,5- and 1,6-allenynes and 1,5-enallenes with bis(pinacolato)diboron affords synthetically useful allylboronates and alkylboronates under smooth conditions in a formal hydroborylative carbocyclization reaction. One C-C and one
- Pardo-Rodriguez, Virtudes,Marco-Martinez, Juan,Bunuel, Elena,Cardenas, Diego J.
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supporting information; experimental part
p. 4548 - 4551
(2009/12/07)
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- Combination iminium, enamine and copper(i) cascade catalysis: A carboannulation for the synthesis of cyclopentenes
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A one-pot, multistep reaction cascade to cyclopentenes from α,β-unsaturated ketones and propargylated carbon acids through a combination of organocatalysis and transition metal ion catalysis is reported; the reaction cascade is simple to perform, occurs u
- Yang, Ting,Ferrali, Alessandro,Campbell, Leonie,Dixon, Darren J.
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supporting information; experimental part
p. 2923 - 2925
(2009/02/03)
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- Syntheses of seven-membered rings: Ruthenium-catalyzed intramolecular [5+2] cycloadditions
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The Ru-catalyzed intramolecular [5+2] cycloaddition of cyclopropylenynes is investigated with respect to the regio- and diastereoselectivity as well as the functional group compatibility of the reaction. Evidence for the mechanism as occurring through a ruthenacyclopentene intermediate is elucidated from 1) the study of the diastereoselectivity of the cycloaddition; 2) the effect of variation of substituents on the regioselectivity of cyclopropyl bond cleavage in 1,2-trans- and 1,2-cis-disubstituted cyclopropanes and 3) examples that clearly do not involve ruthenacyclohexene as intermediates as products still incorporate the cyclo propyl moiety. The scope and limitations of the Ru-catalyzed cycloaddition are discussed and compared with the Rh-catalyzed reaction. The potential power of this methodology towards natural product total synthesis is demonstrated by the formation of several polycyclic systems with the chosen reaction conditions and readily available cyclopropylenyne substrates.
- Trost, Barry M.,Shen, Hong C.,Horne, Daniel B.,Toste, F. Dean,Steinmetz, Bernhard G.,Koradin, Christopher
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p. 2577 - 2590
(2007/10/03)
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- Unexpected remarkable stability of primary ozonides derived from alkenyl stannanes. One-pot synthesis of 1,2-diols from alkynes
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(Matrix Presented) Primary ozonides derived from alkenyl stannanes display an unusual stability and can be transformed into 1,2-diols by treatment with dimethyl sulfide and borane-methyl sulfide complex. This observation has been incorporated into the development of a novel one-pot strategy for the conversion of alkynes into 1,2-diols.
- Gomez, Ana M.,Company, Maria D.,Valverde, Serafin,Lopez, J. Cristobal
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p. 383 - 386
(2007/10/03)
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- Synthesis of variously substituted allenediynes and their cobalt (I)- mediated [2+2+2] cycloaddition reactions
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Syntheses of variously substituted allenediynes where the allene moiety is at the terminal or internal position are described. Their cobalt(I)- mediated [2+2+2] cycloaddition reactions led to the corresponding η4- complexed tricyclic compounds; the regioselectivity of these cyclizations depending on the substitution and the position of the allene is discussed.
- Llerena, Dominique,Buisine, Olivier,Aubert, Corinne,Malacria, Max
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p. 9373 - 9392
(2007/10/03)
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- First examples of cobalt-mediated formal Alder ene reaction of allenynes
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CpCo(CO)2 catalyzes the Alder ene reaction of allenynes 1 to afford six-membered carbocycles in a totally regioselective manner through, presumably, η3-allyl hydride complexes mechanism.
- Llerena, Dominique,Aubert, Corinne,Malacria, Max
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p. 7027 - 7030
(2007/10/03)
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- Iodine atom transfer addition reactions with alkynes. Part 2: α-iodocarbonyls
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1°-Iodo esters, ketones, and nitriles react smoothly in atom transfer addition reactions with alkylsubstituted (nucleophilic) alkynes, but a 3°-iodoester prefers to add to ester-substituted (electrophilic) alkynes. These atom transfer additions are suited
- Curran,Kim,Ziegler
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p. 6189 - 6196
(2007/10/02)
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- Metal carbene chelates: stable reactive intermediates in cycloaddition reactions
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Carbonylcarbene complexes bearing either heteroatoms or C=C bonds in a carbene γ-position are susceptible towards facile decarbonylation.The coordination of the additional donor group affords stable five-membered metal carbene chelates.Olefin-chelated metallacycles are obtained via aminolysis of alkoxy carbene complexes using allylamine.Heteroatom metal carbene chelates are accessible from ortho-lithiated methoxyarenes in a two-step process involving a sequential nucleophile/electrophile addition to metal carbonyls followed by thermal decarbonylation.Both types of compounds have been studied systematically by X-ray analysis.The characteristic feature of oxametallacycles is a long metal to oxygen bond.The ready ring-opening is exploited in the carbene annulation reaction in which now the ligand coupling can be separated from the generation of a vacant coordination site at the metal template.The scope of this strategy is demonstrated by two approaches to anthracyclinones: Either ring B or ring C can be formed from 1,4-dimethoxy-2-naphtylcarbene or anisylcarbene synthons.
- Doetz, Karl Heinz,Popall, Michael,Mueller, Gerhard
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- Intramolecular Reactions of N-Nitrenes with Alkynes: Conformational Anchoring in Spiro-fused 2H-Azirines
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Oxidations of N-aminoquinazolin-4(3H)-ones (7)-(11) with lead tetra-acetate in dichloromethane results in the intramolecular addition of the N-nitrene to the triple bond in each case and azirines (20), (22), (17), (23), and (30), respectively, are isolated with (31) identified as a by-product in the oxidation of compound (11).An X-ray crystal structure determination on compound (17) reveals a remarkable deformation of bond angles at the spiro centre and this feature appears to be common to all azirines.The five membered ring in the azirines (17), (20), (22), and (23) has the envelope conformation (26) and the six-membered ring in the azirine (30) has the twist-boat conformation (32): a possible explanation for this conformational anchoring is offered.
- Atkinson, Robert S.,Grimshire, Michael J.
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p. 1215 - 1224
(2007/10/02)
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