Enantioselective Polyene Cyclization Catalyzed by a Chiral Brønsted Acid

Fan, Liwen; Han, Chao; Li, Xuerong; Yao, Jiasheng; Wang, Zhengning; Yao, Chaochao; Chen, Wei-Hao; Wang, Tao; Zhao, Junfeng

doi:10.1002/anie.201711603

Cited by 38 publications

(17 citation statements)

References 61 publications

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“…11d The products contain halides, olefins or vinyl groups for further manipulation. Organocatalytic initiation methods developed by Jacobsen, 12a MacMillan, 12b and Zhao, 12c although highly selective, require specially engineered substrates that are not easily diversifiable postcyclization. A high-yielding, selective, and operationally simple method for the cyclization of unmodified polyene substrates which also installs useful A-ring functionality is still lacking.…”

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confidence: 99%

Enantioselective, Lewis Base-Catalyzed Sulfenocyclization of Polyenes

et al. 2018

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A sulfenium-ion-initiated, catalytic, enantio-selective polyene cyclization is described. Homogeranylar-enes and ortho-geranylphenols undergo polycyclization in good yield, diastereoselectivity, and enantioselectivity. The stereodetermining step is the generation of an enantio-merically enriched thiiranium ion from a terminal alkene and a sulfenylating agent in the presence of a chiral Lewis basic catalyst. The use of hexafluoroisopropyl alcohol as the solvent is crucial to obtain good yields. The thioether moiety resulting from the reaction can be subsequently transformed into diverse oxygen and carbon functionality postcyclization. The utility of this method is demonstrated by the enantioselective syntheses of (+)-ferruginol and (+)-hinokiol.

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confidence: 99%

Enantioselective, Lewis Base-Catalyzed Sulfenocyclization of Polyenes

et al. 2018

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“…The use of saturated amines as substrates is very rare. We developed a cascade reaction of Pd‐catalyzed γ−C( sp 3 )−H arylation and Ru‐catalyzed oxidation to transform cyclohexanamine into β‐aryl‐substituted cyclohexanone 11 a – 11 d in 42∼63 % yield [37] . The oxidation of amines by the catalytic use of tetrapropylammonium perruthenate (TPAP) along with 1.5 equivalents of N ‐methylmorpholine N ‐oxide provided imines easily, and subsequent acidic workup generated the corresponding ketones.…”

Section: Resultsmentioning

confidence: 99%

Pd‐Catalyzed Regio‐ and Stereoselective sp³ C−H Arylation of Primary Aliphatic Amines: Mechanistic Studies and Synthetic Applications

Choi

Park

et al. 2021

Eur J Org Chem

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The Pd‐catalyzed γ‐position sp3−C−H arylation of primary amines bearing an aliphatic chain or cycloalkyl substituent and related mechanistic studies are disclosed. 3‐Bromo‐2‐hydroxybenzaldehyde plays a key role in γ‐position sp3−C−H arylation as a transient directing group (TDG) to assist the regio‐ and stereoselective C−H activation of a Pd catalyst, and the development of a tandem reaction to transform 1°‐amines into γ‐aryl‐substituted ketones demonstrates synthetic utility. Density functional theory (DFT)‐based calculations revealed the detailed reaction mechanism and the origins of the high selectivity (γ‐position and cis‐only). The X‐ray crystal structure of the isolated endo‐palladacycle intermediate supported the DFT results, and a kinetic isotope experiment confirmed the results of DFT calculations indicating that the C−H activation step via simultaneous palladation and deprotonation is rate‐determining.

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“…The first enantioselective polyene cyclization initiated by a BINOL-derived chiral N-phosphoramide (NPA) catalyzed protonation of an imine was reported by Zhao. 54 The ion-pair formed between the iminium ion and chiral counter anion of the NPA played an important role for controlling the stereochemistry of the overall transformation. This strategy offered a highly efficient approach to fused tricyclic frameworks containing three contiguous stereocenters, which are widely found in natural products.…”

Section: Scheme 38mentioning

confidence: 99%