132145-61-0Relevant articles and documents
Donor-Acceptor Bicyclopropyls as 1,6-Zwitterionic Intermediates: Synthesis and Reactions with 4-Phenyl-1,2,4-triazoline-3,5-dione and Terminal Acetylenes
Potapov, Konstantin V.,Denisov, Dmitry A.,Glushkova, Valeriia V.,Novikov, Roman A.,Tomilov, Yury V.
, p. 15562 - 15576 (2020/11/30)
The bicyclopropyl system activated by incorporation of donor and acceptor groups in the presence of Lewis acids was used as a synthetic equivalent of 1,6-zwitterions. Opening of both cyclopropane rings in 2′-aryl-1,1′-bicyclopropyl-2,2-dicarboxylates (D-A bicyclopropyl, ABCDs) in the presence of GaI3 + Bu4N+GaI4- results in 5-iodo-5-arylpent-2-enylmalonates as products of HI formal 1,6-addition to the bicyclopropyl system. The use of GaCl3 or GaBr3 as a Lewis acid and terminal aryl or alkyl acetylenes as 1,6-zwitterion interceptors allows the alkyl substituent to be grown to give the corresponding acyclic 7-chloro(bromo)-hepta-2,6-dienylmalonates. The reaction of ABCDs with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) catalyzed by Yb(OTf)3 also results in the opening of both cyclopropane rings. The reaction products are tetrahydropyridazine derivatives - (7,9-dioxo-1,6,8-triazabicyclo[4.3.0]non-3-en-2-ylmethyl)malonates - containing one more PTAD moiety in the malonyl group.
Radical-Cation Vinylcyclopropane Rearrangements by TiO2Photocatalysis
Maeta, Naoya,Kamiya, Hidehiro,Okada, Yohei
, p. 6551 - 6566 (2020/07/14)
Radical cation vinylcyclopropane rearrangements by TiO2 photocatalysis in lithium perchlorate/nitromethane solution are described. The reactions are triggered by oxidative single electron transfer, which is followed by immediate ring-opening of the cyclopropanes to generate distonic radical cations as unique reactive intermediates. This approach can also be applied to vinylcyclobutane, leading to the construction of six-membered rings. A stepwise mechanism via distonic radical cations is proposed based on preliminary mechanistic studies, which is supported by density functional theory calculations.
Difluoroacetaldehyde N-Triftosylhydrazone (DFHZ-Tfs) as a Bench-Stable Crystalline Diazo Surrogate for Diazoacetaldehyde and Difluorodiazoethane
Bi, Xihe,Dong, Yuanqing,Gai, Yi,Ning, Yongquan,Reddy, Bhoomireddy Rajendra Prasad,Sivaguru, Paramasivam,Wang, Yingying,Zanoni, Giuseppe,Zhang, Xinyu
supporting information, p. 6473 - 6481 (2020/03/10)
Despite the growing importance of volatile functionalized diazoalkanes in organic synthesis, their safe generation and utilization remain a formidable challenge because of their difficult handling along with storage and security issues. In this study, we developed a bench-stable difluoroacetaldehyde N-triftosylhydrazone (DFHZ-Tfs) as an operationally safe diazo surrogate that can release in situ two low-molecular-weight diazoalkanes, diazoacetaldehyde (CHOCHN2) or difluorodiazoethane (CF2HCHN2), in a controlled fashion under specific conditions. DFHZ-Tfs has been successfully employed in the Fe-catalyzed cyclopropanation and Doyle–Kirmse reactions, thus highlighting the synthetic utility of DFHZ-Tfs in the efficient construction of molecule frameworks containing CHO or CF2H groups. Moreover, the reaction mechanism for the generation of CHOCHN2 from CF2HCHN2 was elucidated by density functional theory (DFT) calculations.
Metal-free domino Cloke-Wilson rearrangement-hydration-dimerization of cyclopropane carbaldehydes: A facile access to oxybis(2-aryltetrahydrofuran) derivatives
Banerjee, Prabal,Dey, Raghunath,Rajput, Shruti
, (2020/03/13)
In this work, we have demonstrated a metal-free transformation of cyclopropane carbaldehydes to oxybis(2-aryltetrahydrofuran) derivatives via a domino Cloke-Wilson rearrangement-hydration-dimerization sequence. Commercially inexpensive p-toluene sulfonic acid (PTSA) was used as a Br?nsted acid catalyst, and reactions were conducted in an open-flask. Detection of reaction intermediates were carried to get an insight into the reaction pathway.
Regioselective Br?nsted Acid-Catalyzed Annulation of Cyclopropane Aldehydes with N′-Aryl Anthranil Hydrazides: Domino Construction of Tetrahydropyrrolo[1,2- a]quinazolin-5(1 H)ones
Banerjee, Prabal,Kaur, Navpreet,Singh, Priyanka
, p. 3393 - 3406 (2020/03/23)
A highly regioselective synthesis of tetrahydropyrrolo[1,2-a]quinazolin-5(1H)one derivatives was achieved by reacting cyclopropane aldehydes with N′-aryl anthranil hydrazides in the presence of p-toluene sulfonic acid (PTSA). The transformation involves domino imine formation and intramolecular cyclization to form 2-arylcyclopropyl-2,3-dihydroquinolin-4(1H)-one, followed by nucleophilic ring opening of the cyclopropyl ring to form desired tetrahydropyrrolo[1,2-a]quinazolin-5(1H)one in good to excellent yield with complete regioselectivity. This protocol tolerates a great variety of functional groups and thus provides a simple and step-efficient method for pyrroloquinazolinone synthesis.
Accessing dihydro-1,2-oxazine via cloke-wilson-type annulation of cyclopropyl carbonyls: application toward the diastereoselective synthesis of pyrrolo[1,2- b][1,2]oxazine
Banerjee, Prabal,Kumar, Pankaj,Kumar, Rakesh
, p. 6535 - 6550 (2020/06/09)
A convenient additive-free synthesis of dihydro-4H-1,2-oxazines via a Cloke-Wilson-type ring expansion of the aryl-substituted cyclopropane carbaldehydes with the hydroxylamine salt is introduced. Comparatively less active cyclopropyl ketones also follow a similar protocol if supplemented by catalytic p-toluene sulfonic acid monohydrate. The transformation is performed in an open-to-air flask as it shows negligible sensitivity toward air/moisture. Dihydro-4H-1,2-oxazines when subjected to cycloaddition with the cyclopropane diester afford a trouble-free formulation of the valued hexahydro-2H-pyrrolo[1,2-b][1,2]oxazine derivatives. A cascade one-pot variant of this two-step strategy offers a comparable overall yield of the final product.
Au Nanoparticle-Catalyzed Silaboration of Aryl-Substituted Cyclopropyl Aldehydes Forming Rearranged β-Boronate Silyl Enol Ethers
Kotzabasaki, Vasiliki,Kidonakis, Marios,Vassilikogiannaki, Eleni,Stratakis, Manolis
, p. 7233 - 7236 (2019/11/19)
2-Aryl-substituted cyclopropyl aldehydes undergo an unprecedented Au nanoparticle-catalyzed silaboration leading to rearranged linear β-boronate-bearing silyl enol ethers. Formation of these products is attributed to the ring opening radical clock rearran
Metal-Free Ring Opening Cyclization of Cyclopropane Carbaldehydes and N-Benzyl Anilines: An Eco-Friendly Access to Functionalized Benzo[b]azepine Derivatives
Dey, Raghunath,Banerjee, Prabal
, p. 2849 - 2854 (2019/04/26)
Herein, we report a p-toluenesulfonic acid (PTSA) initiated mild and user-friendly ring opening/domino ring opening cyclization reaction (depends on substituent present in N-benzyl aniline) of cyclopropane carbaldehyde and N-benzyl aniline towards the formation of substituted 4-amino butanal/2,3-dihydro-1H-benzo[b]azepine. The product dihydro-1H-benzo[b]azepine was also converted into the corresponding tetrahydro-1H-benzo[b]azepine. (Figure presented.).
Lewis Acid Catalyzed Annulation of Cyclopropane Carbaldehydes and Aryl Hydrazines: Construction of Tetrahydropyridazines and Application Toward a One-Pot Synthesis of Hexahydropyrrolo[1,2- b]pyridazines
Dey, Raghunath,Kumar, Pankaj,Banerjee, Prabal
, p. 5438 - 5449 (2018/05/28)
In this report, a facile synthesis of tetrahydropyridazines via a Lewis acid catalyzed annulation reaction of cyclopropane carbaldehydes and aryl hydrazines has been demonstrated. Moreover, the generated tetrahydropyridazine further participated in a cycloaddition reaction with donor-acceptor cyclopropanes to furnish hexahydropyrrolo[1,2-b]pyridazines. We also performed these two steps in one pot in a consecutive manner. In addition, a monodecarboxylation reaction of hexahydropyrrolo[1,2-b]pyridazine was achieved with a good yield.
Exploitation of Cyclopropane Carbaldehydes to Prins Cyclization: Quick Access to (E)-Hexahydrooxonine and Octahydrocyclopenta[ b]pyran
Kumar, Pankaj,Dey, Raghunath,Banerjee, Prabal
, p. 5163 - 5166 (2018/09/13)
A single-step TiX4-mediated Prins-type cyclization of cyclopropane carbaldehydes with 3-buten-1-ol for the highly stereoselective construction of relatively strained (E)-hexahydrooxonines is reported. Switching the alcohol to 3-butyn-1-ol prompted a similar route, augmented by another cyclization within a nine-membered ring to afford a bicyclized product (4,4-dihalo-5-aryloctahydrocyclopenta[b]pyran). Easy transformation of the resulting geminal dihalide to a vinyl halide and a ketone further supplemented the substance of this approach.
