Asymmetric Ring‐Opening Reactions of Donor‐Acceptor Cyclopropanes and Cyclobutanes

Wang, Lijia; Tang, Yong

doi:10.1002/ijch.201500094

Cited by 105 publications

(25 citation statements)

References 68 publications

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“…The typical cycloaddition of DACs with unsaturated compounds can be used to construct five‐, six‐, and seven‐membered carbocyclic and heterocyclic compounds . The nucleophilic ring opening of DACs with a variety of heteroatomatic and carbon nucleophiles is demonstrated as a flexible tool to create C−X bonds ––. DACs, particularly 2‐aryl cyclopropane‐1,1‐dicarboxylates, have high ring strain, and the corresponding cation and anion intermediates formed by heterolysis of the cyclopropane ring are relatively stable.…”

Section: Methodsmentioning

confidence: 99%

Intramolecular Arylative Ring Opening of Donor‐Acceptor Cyclopropanes in the Presence of Triflic Acid: Synthesis of 9H‐Fluorenes and 9,10‐Dihydrophenanthrenes

Wang

Zhao

et al. 2019

Asian J Org Chem

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A unique intramolecular arylative ring opening of 2-biaryl substituted donor-acceptor cyclopropanes in the presence of triflic acid was found, furnishing 9H-fluorenes and 9,10-dihydrophenanthrenes. Chemoselectivity between both products is achieved by modification of the solvent, temperature, and amount of triflic acid. Representative large-scale experiments were also carried out successfully with good outcomes.Donor-acceptor cyclopropanes (DACs) are versatile building blocks in organic synthesis for assembling various classes of compounds. The typical cycloaddition of DACs with unsaturated compounds can be used to construct five-, six-, and sevenmembered carbocyclic and heterocyclic compounds. [1] The nucleophilic ring opening of DACs with a variety of heteroatomatic and carbon nucleophiles is demonstrated as a flexible tool to create CÀ X bonds. [1b-c,f-h,j,2] DACs, particularly 2-aryl cyclopropane-1,1-dicarboxylates, have high ring strain, and the corresponding cation and anion intermediates formed by heterolysis of the cyclopropane ring are relatively stable. As a result, DACs usually serve as 1,3-zwitterionic intermediates under the catalysis of Lewis acid or Brønsted acid, and proceed by nucleophilic addition at their C1 position (Scheme 1a). Recently, generation of 1,2-zwitterions from DACs under specified conditions was explored, [3] and some C2-addition reactions were reported (Scheme 1a). [4] Arylative ring opening of 2-aryl substituted DACs forms substituted diarylmethanes by C1-addition (Scheme 1b). Several arylative nucleophiles have been explored, including indoles, [5] benzo[b]furan, [6] electron-rich arenes, [7] polycyclic aromatic species, [7b,g,8] and arylboronic acids bearing electron-donating groups. [9] All of the arylative reactants are relatively reactive nucleophiles, and most of the arylation reactions are intermolecular. [10] However, it is well known that intramolecular reaction can be relatively easily achieved. Hence we assumed that the intramolecular arylative ring opening of DACs with less reactive arenes was possible. The intramolecular reactions would enlarge the limited range of nucleophiles in this type of reaction.With this perspective, we decided to test the intramolecular arylative ring opening of 2-(2'-biphenyl) cyclopropane-1,1dicarboxylate (1 a) to assess the nucleophilicity of the general aryl group (Table 1). When 1 a was treated with one equivalent of triflic acid (TfOH) at room temperature, the C1-addition product, 9H-fluorene 2 a, was indeed formed, but surprisingly, the C2-addition product, 9,10-dihydrophenanthrene 3 a, was obtained as the major product (entry 1). The proportion of 2 a increased with the increasing temperature (entry 2) or loading amount of TfOH (entry 3-5). An excellent yield (95%) of pure 2 a could be obtained when excess TfOH was used (entry 5). On the contrary, lowering the temperature or loading amount of [a]

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Section: Methodsmentioning

confidence: 99%

Intramolecular Arylative Ring Opening of Donor‐Acceptor Cyclopropanes in the Presence of Triflic Acid: Synthesis of 9H‐Fluorenes and 9,10‐Dihydrophenanthrenes

Wang

Zhao

et al. 2019

Asian J Org Chem

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“…The dipolar nature of D‐A cyclopropanes allows both electrophilic and nucleophilic activation. Lewis acid catalysis can promote the activation of D‐A cyclopropanes, thus leading to an increased electrophilic character of the system which has resulted in, for example, ring‐opening, addition, and cycloaddition reactions –. In contrast to the electrophilic activation of D‐A cyclopropanes, nucleophilic activation strategies are less common and only little progress has been achieved since the initial work by the groups of Reissing– and Wenkert …”

Section: Methodsmentioning

confidence: 99%

Directing the Activation of Donor–Acceptor Cyclopropanes Towards Stereoselective 1,3‐Dipolar Cycloaddition Reactions by Brønsted Base Catalysis

et al. 2017

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The first stereoselective organocatalyzed [3+ +2] cycloaddition reaction of donor-acceptor cyclopropanes is presented. It is demonstrated that by applying an optically active bifunctional Brønsted base catalyst, racemic di-cyano cyclopropylketones can be activated to undergo as tereoselective 1,3-dipolar reaction with mono-and polysubstituted nitroolefins.The reaction affords functionalizedcyclopentanes with three consecutive stereocenters in high yield and stereoselectivity.Based on the stereochemical outcome,amechanism in which the organocatalyst activates both the donor-acceptor cyclopropane and nitroolefin is proposed. Finally,c hemoselective transformations of the cycloaddition products are demonstrated.

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“…Communications Thea minocyclopropane 7 [11] was detected as ar eaction intermediate by 1 HNMR analysis,indicating that the reaction may undergo ac yclopropanation with arhodium carbene [10b] and the terminal olefin, followed by an intramolecular annulation of indole with the in situ formed aminocyclopropane. [12][13][14] To further understand the reaction pathways,a ni ns itu 1 HNMR study of the reaction mixtures was carried out in CD 2 Cl 2 . [11] Firstly 1a, 2,a nd Rh 2 (esp) 2 ,w ithout InCl 3 ,w ere placed in the NMR tube at À40 8 8C.…”

Section: Angewandte Chemiementioning

confidence: 99%

Selectivity Switch in a Rhodium(II) Carbene Triggered Cyclopentannulation: Divergent Access to Three Polycyclic Indolines

et al. 2019

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A selectivity switch in a RhII/carbene‐triggered cyclopentannulation with catalytic InCl3 is reported for the first time, affording both diastereomers of the fused spiroindolines and an unusual bridged tetracyclic indoline in high yields with excellent selectivities. Mechanistic studies indicate an intramolecular annulation of the indole with an in situ formed aminocyclopropane. The stepwise thermal conversions from the kinetic spiroindoline to the metastable bridged indoline, and then to the thermodynamic spiroindoline, involving a ring‐opening rearrangement of a cyclopentane, is crucial for selectivity control.

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Asymmetric Ring‐Opening Reactions of Donor‐Acceptor Cyclopropanes and Cyclobutanes

Cited by 105 publications

References 68 publications

Intramolecular Arylative Ring Opening of Donor‐Acceptor Cyclopropanes in the Presence of Triflic Acid: Synthesis of 9H‐Fluorenes and 9,10‐Dihydrophenanthrenes

Intramolecular Arylative Ring Opening of Donor‐Acceptor Cyclopropanes in the Presence of Triflic Acid: Synthesis of 9H‐Fluorenes and 9,10‐Dihydrophenanthrenes

Directing the Activation of Donor–Acceptor Cyclopropanes Towards Stereoselective 1,3‐Dipolar Cycloaddition Reactions by Brønsted Base Catalysis

Selectivity Switch in a Rhodium(II) Carbene Triggered Cyclopentannulation: Divergent Access to Three Polycyclic Indolines

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