A Strategy Enabling Enantioselective Direct Conjugate Addition of Inert Aryl Methane Nucleophiles to Enals with a Chiral Amine Catalyst under Mild Conditions

Li, Tengfei; Zhu, Jin; Wu, Deyan; Li, Xiangmin; Wang, Sinan; Li, Hao; Li, Jian; Wang, Wei

doi:10.1002/chem.201300304

Cited by 81 publications

(39 citation statements)

References 83 publications

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“…[15] We have already reported that ac hiral macrocyclic crown ether, binaphtho-34-crown-10 (34-C-10), could be used to form an effective asymmetric environment around the potassium cation of KHMDS.W eh ave also shown that catalytic asymmetric direct-type 1,4-addition reactions of simple amides,p romoted by K/34-C-10, can be achieved with high enantioselectivities. [16][17][18] Further improvement of the enantioselectivity is ongoing. [16][17][18] Further improvement of the enantioselectivity is ongoing.…”

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confidence: 99%

Catalytic Direct‐type 1,4‐Addition Reactions of Alkylazaarenes

et al. 2017

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1,4-addition reactions of alkylazaarenes catalyzed by strong Brønsted bases have been developed for the first time. The desired reactions with α,β-unsaturated amides proceeded under mild reaction conditions to give the 1,4-adducts in high yields. Both ortho- and para-substituted azaarenes afforded the desired adducts in high yields. Regioselective reactions of di- or trimethylpyridine were found to be possible depending on the acidity of the α-hydrogen atoms. Furthermore, a candidate of allosteric protein kinase modulators was synthesized in two steps. An asymmetric variant of this reaction was also found to be feasible.

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confidence: 99%

Catalytic Direct‐type 1,4‐Addition Reactions of Alkylazaarenes

et al. 2017

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“…The in-situ generation of a carbanion at the α-position of the benzyl halide could initiate the organocascade reaction, [16] in which the α,β-unsaturated aldehyde, activated by an aminocatalyst, would act as electrophilic counterpart; the following irreversible intramolecular alkylation would give the benzylic cyclopropanated products by iminium and enamine activation. Surprisingly, diphenyl prolinol IV and MacMillan's second-generation imidazolidinone catalyst V, which has been previously used by Lattanzi and co-workers in similar MIRC reactions with excellent results, did not catalyze the reaction to any significant extent, yielding only a trace amount of product (Table 1, entries [10][11]. We also investigated the effect of the reaction temperature on the yield and selectivity.…”

Section: Scheme 1 Aryl Methane Derivatives Serving As Pseudo-benzylimentioning

confidence: 97%

Enantioselective Organocatalytic Cyclopropanation of Enals Using Benzyl Chlorides

et al. 2016

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Herein we describe the first enantioselective cyclopropanation of enals using benzyl chlorides as bifunctional (nucleophilic and electrophilic) reagents. The reaction is simply catalyzed by chiral secondary amines to afford the formyl cyclopropane derivatives in good yields and with moderate to excellent stereoselectivities.  INTRODUCTIONCyclopropane subunits have always fascinated organic chemists because of their unusual structural properties and their wide presence in natural products and pharmaceuticals. The cyclopropane skeletal structure is often found in terpenes, pheromones, fatty acid metabolites, and unnatural amino acids; moreover, its derivatives present a plethora of biological activities such as insecticidal, antibiotic, antifungal, antitumor, and antiviral properties. For these reasons, many scientists are interested in developing new enantioselective methods for the construction of cyclopropanes.Since the seminal report of Simmons and Smith on the reaction of alkenes with diiodomethane in the presence of zinc dust to afford cyclopropanes in high yields, 1 several asymmetric versions of cyclopropanations were reported. These methodologies rely either on the use of stoichiometric amounts of chiral auxiliaries or promoters with allylic alcohols (or amines), α,β-

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“…Wang and co‐workers reported the addition of methylnitropyridines to enals with excellent yields and enantioselectivities. Unfortunately 2‐methyl‐5‐nitropyridines did not give good results under these conditions (Scheme ) …”

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confidence: 99%