Catalytic Asymmetric 6π Electrocyclization: Enantioselective Synthesis of Functionalized Indolines

Maciver, Eleanor E.; Thompson, Sam; Smith, Martin D.

doi:10.1002/ange.200905169

Cited by 30 publications

(10 citation statements)

References 66 publications

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“…Quenching of this anion with an appropriate electrophile would also give access to all-carbon quaternary stereocentres. Our previous investigations into the counterion-directed cyclization of delocalized anions to form indolines [17,18] and indolenines [19] has demonstrated that analogous transformations can proceed with high enantioselectivity.…”

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confidence: 99%

Catalytic enantioselective synthesis of indanes by a cation-directed 5-endo-trig cyclization

et al. 2015

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5-Endo-trig cyclizations are generally considered to be kinetically unfavourable, as described by Baldwin's rules. Consequently, observation of this mode of reaction under kinetic control is rare. This is usually ascribed to challenges in achieving appropriate approach trajectories for orbital overlap in the transition state. Here, we describe a highly enantio- and diastereoselective route to complex indanes bearing all-carbon quaternary stereogenic centres via a 5-endo-trig cyclization catalysed by a chiral ammonium salt. Through computation, the preference for the formally disfavoured 5-endo-trig Michael reaction over the formally favoured 5-exo-trig Dieckmann reaction is shown to result from thermodynamic contributions to the innate selectivity of the nucleophilic group, which outweigh the importance of the approach trajectory as embodied by Baldwin's rules. Our experimental and theoretical findings demonstrate that geometric and stereoelectronic constraints may not be decisive in the observed outcome of irreversible ring-closing reactions.

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confidence: 99%

Catalytic enantioselective synthesis of indanes by a cation-directed 5-endo-trig cyclization

et al. 2015

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“…Treatment of an in situ generated N-aryl imine 180 with K 2 CO 3 in the presence of catalyst 2 v afforded the cyclized product 181 in good yield and high enantioselectivity (Scheme 115). [150] Brire and co-workers reported the asymmetric [3+2] cycloaddition of allylic sulfone 182 and chalcone under phasetransfer conditions. The reaction was promoted by the simplified Maruoka catalyst (S)-4 a to give product 183 with moderate enantioselectivity (Scheme 116).…”

Section: Other Cyclizationsmentioning

confidence: 99%

Recent Developments in Asymmetric Phase‐Transfer Reactions

2013

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Phase-transfer catalysis has been recognized as a powerful method for establishing practical protocols for organic synthesis, because it offers several advantages, such as operational simplicity, mild reaction conditions, suitability for large-scale synthesis, and the environmentally benign nature of the reaction system. Since the pioneering studies on highly enantioselective alkylations promoted by chiral phase-transfer catalysts, this research field has served as an attractive area for the pursuit of "green" sustainable chemistry. A wide variety of asymmetric transformations catalyzed by chiral onium salts and crown ethers have been developed for the synthesis of valuable organic compounds in the past several decades, especially in recent years.

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“…Such strategies have been well documented, including a chiral synthon strategy, [5] metal catalysis, [6] and organocatalysis. [7] Despite these impressive advances, the development of a direct method for the synthesis of enantioenriched 2-substituted indolines continues to be highly desirable.…”

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confidence: 99%

Construction of Optically Active Indolines by Formal [4+1] Annulation of Sulfur Ylides and N‐(ortho‐Chloromethyl)aryl Amides

Yang

Wang

et al. 2013

Chemistry A European J

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Catalytic Asymmetric 6π Electrocyclization: Enantioselective Synthesis of Functionalized Indolines

Abstract: Scheme 1. Strategic approach to asymmetric electrocyclization.Scheme 2. Catalysts examined in this study.

Cited by 30 publications

References 66 publications

Catalytic enantioselective synthesis of indanes by a cation-directed 5-endo-trig cyclization

Catalytic enantioselective synthesis of indanes by a cation-directed 5-endo-trig cyclization

Recent Developments in Asymmetric Phase‐Transfer Reactions

Construction of Optically Active Indolines by Formal [4+1] Annulation of Sulfur Ylides and N‐(ortho‐Chloromethyl)aryl Amides

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