- α-Oxocarboxylic Acids as Three-Carbon Insertion Units for Palladium-Catalyzed Decarboxylative Cascade Synthesis of Diverse Fused Heteropolycycles
-
A novel palladium-catalyzed decarboxylative cascade cyclization for the assembly of diverse fused heteropolycycles by employing α-oxocarboxylic acids as three-carbon insertion units is reported. This protocol enables the synthesis of isoquinolinedione- and indolo[2,1-a]isoquinolinone-fused benzocycloheptanones in moderate to good yields by the use of different aryl iodides, including alkene-tethered 2-iodobenzamides and 2-(2-iodophenyl)-1H-indoles. Notably, the approach achieves simultaneous construction of both six- and seven-membered rings via sequential intramolecular carbopalladation, C-H activation, and decarboxylation.
- Zhou, Liwei,Qiao, Shujia,Zhou, Fengru,Xuchen, Xinyu,Deng, Guobo,Yang, Yuan,Liang, Yun
-
supporting information
p. 2878 - 2883
(2021/05/05)
-
- Atmosphere-Controlled Palladium-Catalyzed Divergent Decarboxylative Cyclization of 2-Iodobiphenyls and α-Oxocarboxylic Acids
-
A novel palladium-catalyzed divergent decarboxylative cyclization of 2-iodobiphenyls and α-oxocarboxylic acids utilizing the atmosphere as a controlled switch is reported. Under the protection of a nitrogen atmosphere, tribenzotropones are synthesized by a [4 + 3] decarboxylative cyclization. Employing a palladium/O2 system enables a [4 + 2] decarboxylative cyclization to assemble triphenylenes. Notably, preliminary mechanistic studies indicate that the formation of triphenylenes involves a double decarboxylation.
- Zhou, Liwei,Sun, Mingjie,Zhou, Fengru,Deng, Guobo,Yang, Yuan,Liang, Yun
-
supporting information
p. 7150 - 7155
(2021/09/18)
-
- Asymmetric Synthesis and Application of Chiral Spirosilabiindanes
-
Reported here is the development of a class of chiral spirosilabiindane scaffolds by Rh-catalyzed asymmetric double hydrosilation, for the first time. Enantiopure SPSiOL (spirosilabiindane diol), a new type of chiral building block for the preparation of various chiral ligands and catalysts, was readily prepared on greater than 10 gram scale using this protocol. The potential of this new spirosilabiindane scaffold in asymmetric catalysis was preliminarily demonstrated by development of the corresponding monodentate phosphoramidite ligands (SPSiPhos), which were used in both a Rh-catalyzed hydrogenation and a Pd-catalyzed intramolecular carboamination.
- Chang, Xin,Chen, Hong-Chao,Li, Chuan-Ying,Ma, Pei-Long,Wang, Peng
-
supporting information
p. 8937 - 8940
(2020/04/30)
-
- Asymmetric Synthesis of 1,2-Dihydronaphthalene-1-ols via Copper-Catalyzed Intramolecular Reductive Cyclization
-
We describe a copper-catalyzed intramolecular reductive cyclization of easily accessible benz-tethered 1,3-dienes containing a ketone moiety. This process provided biologically active 1,2-dihydronaphthalene-1-ol derivatives in good yields with excellent enantio- and diastereoselectivity. Mechanistic investigations using density functional theory revealed that (Z)- and (E)-allylcopper intermediates formed in situ from the diene and copper catalyst undergo isomerization and selective intramolecular allylation of the (E)-allylcopper form of the major product through a six-membered boatlike transition state. The resulting products were further transformed to fully saturated naphthalene-1-ols by reactions of the olefin moiety.
- Acharyya, Ranjan Kumar,Kim, Soyoung,Park, Yeji,Han, Jung Tae,Yun, Jaesook
-
supporting information
p. 7897 - 7902
(2020/11/02)
-
- Phosphine- and water-promoted pentannulative aldol reaction
-
Herein, an efficient metal-free intramolecular aldol reaction for the synthesis of an unusual class of cyclopentanoids is described. The reaction of α-substituted dienones tethered with ketones in the presence of tributylphosphine and water provided aldols. The role of water was realised to be crucial for this transformation. Furthermore, isotopic labeling experiments provided vital information about the reaction mechanism.
- Satpathi, Bishnupada,Dutta, Lona,Ramasastry
-
supporting information
p. 1547 - 1551
(2019/02/14)
-
- From catechol-tocopherol to catechol-hydroquinone polyphenolic antioxidant hybrids
-
Multidefence antioxidants represent a valuable solution for the protection against oxidative stress. From the planned synthesis of a catechol-tocopherol hybrid, we isolated a catechol-hydroquinone hybrid through a BBr3-mediated benzochromene-fluoren-1-ol transposition. The compound prepared showed a remarkable chain-breaking antioxidant in the catechol portion, while the very sensitive hydroquinone moiety revealed to be an efficient generator of hydroperoxyl radicals.
- Viglianisi, Caterina,Menichetti, Stefano,Morelli, Paola,Baschieri, Andrea,Amorati, Riccardo
-
-
- PdII-Catalyzed Oxidative Tandem aza-Wacker/Heck Cyclization for the Construction of Fused 5,6-Bicyclic N,O-Heterocycles
-
A PdII-catalyzed oxidative tandem cyclization was developed for the construction of fused 5,6-bicyclic N, O-heterocycles. This reaction was enabled by the combined use of a 3-methylpyridine ligand and pentafluorobenzoic acid additive. A range of heterocyclic products with different substituents could be prepared in moderate to good yields via this methodology. Several transformations, including a scaled-up preparation of product 2 a, were also carried out showing the good applicability of our methodology.
- Ye, Chenghao,Kou, Xuezhen,Xia, Jingzhao,Yang, Guoqiang,Kong, Li,Wei, Quhao,Zhang, Wanbin
-
supporting information
p. 1897 - 1901
(2018/07/31)
-
- Synthesis of analogues of natural antimitotic glaziovianin A based on dill and parsley seed essential oils
-
Glaziovianin A and its analogues were synthesized in six steps starting from allylpolyalkoxybenzenes separated from essential oils of dill (Anetum graviolens) and parsley (Petro-selinum sativum) seeds.
- Tsyganov, Dmitry V.,Konyushkin, Leonid D.,Semenova, Marina N.,Semenov, Victor V.
-
p. 285 - 287
(2016/08/09)
-
- Efficient Synthesis of Glaziovianin A Isoflavone Series from Dill and Parsley Extracts and Their in Vitro/in Vivo Antimitotic Activity
-
A concise six-step protocol for the synthesis of isoflavone glaziovianin A (GVA) and its alkoxyphenyl derivatives 9 starting with readily available plant metabolites from dill and parsley seeds was developed. The reaction sequence involved an efficient conversion of the key intermediate epoxides 7 into the respective β-ketoaldehydes 8 followed by their Cu(I)-mediated cyclization into the target series 9. The biological activity of GVA and its derivatives was evaluated using a panel of seven human cancer cell lines and an in vivo sea urchin embryo assay. Both screening platforms confirmed the antimitotic effect of the parent GVA (9cg) and its alkoxy derivatives. Structure-activity relationship studies suggested that compounds 9cd and 9cf substituted with trimethoxy- and dillapiol-derived B-rings, respectively, were less active than the parent 9cg. Of the evaluated human cancer cell lines, the A375 melanoma cell line was the most sensitive to the tested molecules. Notably, the target compounds were not cytotoxic against human peripheral blood mononuclear cells up to 10 μM concentration. Phenotypic readouts from the sea urchin assay unequivocally suggest a direct microtubule-destabilizing effect of isoflavones 9cg, 9cd, and 9cf.
- Semenov, Victor V.,Tsyganov, Dmitry V.,Semenova, Marina N.,Chuprov-Netochin, Roman N.,Raihstat, Mikhail M.,Konyushkin, Leonid D.,Volynchuk, Polina B.,Marusich, Elena I.,Nazarenko, Vera V.,Leonov, Sergey V.,Kiselyov, Alex S.
-
p. 1429 - 1438
(2016/06/09)
-
- Palladium-Catalyzed Aerobic Aminooxygenation of Alkenes for Preparation of Isoindolinones
-
A palladium-catalyzed intramolecular isoindolinone-forming aminooxygenation of alkenes with 1 atm of oxygen as oxidant is reported. A variety of functionalized alkenes and carboxylic acids can be used, and high yields were observed. Preliminary mechanistic studies revealed that the aminooxygenation products were formed through the oxidation of a C-PdII species using a strong oxidant, peroxide, which is generated in situ from a Pd(OAc)2/bpy/O2/HOAc catalytic system.
- Kou, Xuezhen,Li, Yu,Wu, Liang,Zhang, Xinghua,Yang, Guoqiang,Zhang, Wanbin
-
supporting information
p. 5566 - 5569
(2015/12/01)
-
- Substitution controlled functionalization of ortho -bromobenzylic alcohols via palladium catalysis: Synthesis of chromenes and indenols
-
An efficient domino Pd-catalyzed transformation of simple ortho-bromobenzyl tertiary alcohols to chromenes is presented. Their formation is believed to proceed via the formation of a five-membered palladacycle, which, in turn, involves in an intermolecular homocoupling with the second ortho- bromobenzyltertiary alcohol to yield the homo-biaryl bond followed by intramolecular C-O bond formation. Interestingly, when there is an allylic substituent on the benzylic carbon atom, a chemoselective switch was observed, which preferred intramolecular Heck coupling and gave indenols. Further, it has been confirmed that the tertiary alcohol functionality is indispensible to give the coupled products, whereas the use of primary/secondary benzylic alcohols furnished the simple carbonyl products via a possible reductive debromination followed by oxidation due to the availability of β-hydrogen(s).
- Mahendar, Lodi,Satyanarayana, Gedu
-
supporting information
p. 2059 - 2074
(2014/04/03)
-
- A high-yielding modular access to the lamellarins: Synthesis of lamellarin G trimethyl ether, lamellarin η and dihydrolamellarin η
-
A deprotonated α-aminonitrile serves as a key intermediate in a highly efficient (95 % per step on average; see scheme) modular synthetic approach to the lamellarin alkaloids. Its reaction with an α,β- unsaturated aldehyde forms the central pyrrole ring in a one-pot procedure. The construction of the fused pentacyclic skeleton is completed by a microwave-assisted Ullmann-type lactone formation.
- Imbri, Dennis,Tauber, Johannes,Opatz, Till
-
p. 15080 - 15083
(2013/11/06)
-
- Sequential one-pot method for oxy-Michael addition, Heck coupling, and degradation followed by condensation: Facile synthesis of 2-benzoxepin-3(1H)- ones Dedicated to the memory of my teacher Professor P.V. Subba Rao, Department of Chemistry, Andhra University, Visakhapatnam
-
A sequential one-pot intermolecular oxy-Michael addition, intermolecular Heck coupling, and intramolecular degradation (retro-oxy-Michael addition) followed by condensation method has been developed for the synthesis of interesting 2-benzoxepin-3(1H)-ones. Significantly, the 2-benzoxepin-3(1H)-ones form the core quantum of biologically vital natural products. The initial oxy-Michael addition and Heck coupling steps involve a straight forward construction of C-O and C-C bonds, whereas, the final condensation step follows a novel mechanistic path via intramolecular degradation, double bond isomerization, and intramolecular condensation. Notably, a remarkable solvent effect has been observed in-order to promote the final intramolecular condensation.
- Reddy, A. Gopi Krishna,Krishna,Satyanarayana
-
p. 10098 - 10107
(2013/11/06)
-
- Base-catalyzed synthesis of substituted indazoles under mild, transition-metal-free conditions
-
Back to basics: A transition-metal-free method developed for the synthesis of indazoles involves an inexpensive catalytic system composed of a diamine and K2CO3. Various (Z)-2-bromoacetophenone tosylhydrazones were converted into indazoles at room temperature in excellent yields (see example; Ts=p-toluenesulfonyl). The yield was improved by photoisomerization with UV light when E/Z isomeric mixtures of the starting material were used. Copyright
- Thome, Isabelle,Besson, Claire,Kleine, Tillmann,Bolm, Carsten
-
supporting information
p. 7509 - 7513
(2013/07/26)
-
- An efficient sequential one-pot base mediated C-O and Pd-mediated C-C bond formation: Synthesis of functionalized cinnamates and isochromenes
-
An efficient sequential one-pot intermolecular oxy-Michael addition and intermolecular Heck coupling for the synthesis of functionalized cinnamates is presented. Bulky tert-butyl acrylate was identified as a more suitable Michael acceptor for initial oxy-Michael addition, as it precludes the formation of undesired cross condensed ester. Most importantly, the present method was further divergently extended to the successful synthesis of isochromenes via a sequential one-pot O-allylation and subsequent intramolecular Heck cyclization.
- Gopi Krishna Reddy,Krishna,Satyanarayana
-
supporting information
p. 5635 - 5640
(2012/10/29)
-
- Development of an intramolecular aryne ene reaction and application to the formal synthesis of (±)-crinine
-
A general and high yielding annulation strategy for the synthesis of various carbo- and heterocycles, based on an intramolecular aryne ene reaction is described. It was found that the geometry of the olefin is crucial to the success of the reaction, with exclusive migration of the trans-allylic-H taking place. Furthermore, the electronic nature of the aryne was found to be important to the success of the reaction. Deuterium labeling studies and DFT calculations provided insight into the reaction mechanism. The data suggests a concerted asynchronous transition state, resembling a nucleophilic attack on the aryne. This strategy was successfully applied to the formal synthesis of the ethanophenanthridine alkaloid (±)-crinine.
- Candito, David A.,Dobrovolsky, Dennis,Lautens, Mark
-
supporting information
p. 15572 - 15580
(2012/11/07)
-
- Synthesis and agonistic activity at the GPR35 of 5,6-dihydroxyindole-2- carboxylic acid analogues
-
5,6-Dihydroxyindole-2-carboxylic acid (DHICA), an intermediate of melanin synthesis and an eumelanin building block, was recently discovered to be a GPR35 agonist with moderate potency. Here, we report the synthesis and pharmacological characterization of a series of DHICA analogues against GPR35 using both label-free dynamic mass redistribution and Tango β-arrestin translocation assays. This led to identification of novel GPR35 agonists with improved potency and/or having biased agonism.
- Deng, Huayun,Fang, Ye
-
scheme or table
p. 550 - 554
(2012/09/05)
-
- A domino palladium-catalyzed C-C and C-O bonds formation via dual O-H bond activation: Synthesis of 6,6-dialkyl-6 H -benzo[ c ]chromenes
-
An efficient Pd-catalyzed domino reaction of α,α-dialkyl-(2- bromoaryl)methanols to 6,6-dialkyl-6H-benzo[c]chromenes is presented. Their formation can be explained via a five membered Pd(II)-cycle that efficiently involves a domino homocoupling with the second molecule, β-carbon cleavage, and finally intramolecular Buchwald-Hartwig cyclization. This domino process effectively involves breaking of five σ-bonds (2C-Br, 2O-H, and a C-C) and formation of two new σ-bonds (C-C and C-O). This mechanistic pathway is unprecedented and further illustrates the power of transition metal catalysis.
- Mahendar, Lodi,Krishna, Jonnada,Gopi Krishna Reddy, Alavala,Venkat Ramulu, Bokka,Satyanarayana, Gedu
-
supporting information; experimental part
p. 628 - 631
(2012/03/11)
-
- Lignanes. 17. Recherches sur la Synthese Totale d'un Norcycloneolignane, la Metasequirine-B
-
The total synthesis of the racemic furano bisbenzocycloheptene 3 is described.The compound 3, which contains five asymmetric centres, is the 5,8-bis-epimer of the tetra-O-methyl derivative of metasequirin-B (1), a norcycloneolignan of unusual structure.
- Sanceau, Jean-Yves,Dhal, Robert,Brown, Eric
-
p. 3363 - 3380
(2007/10/02)
-
- Electrocyclic Reactions of Protonated Chalcones: Synthesis of 3-Arylindan-1-ones
-
A series of ortho-bromochalcones has been prepared and each has been heated and irradiated in strong acid.In most cases a four-electron electrocyclic reaction occurred preferentially to give 3-arylindan-1-ones in good yield.The acrylchalcone 4'-methoxy-3,
- McDonald, Edward,Smith, Paul
-
p. 837 - 842
(2007/10/02)
-