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    Home > Asymmetric allyl alkylation of amidenol catalyzed by angelw: IR

    Asymmetric allyl alkylation of amidenol catalyzed by angelw: IR

    • Last Update: 2019-06-02
    • Source: Internet
    • Author: User
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    As a powerful synthesis method, IR catalyzed asymmetric allyl alkylation can be used for the formation of carbon carbon bond and carbon heterobond Stable enols are a kind of special nucleophiles, which are widely used in the asymmetric allyl Alkylation Catalyzed by IR The structure of amidenol is similar to that of enol, but the acidity of C-H bond of amidenol (affecting the formation of activated allyl iridium intermediate) is significantly lower than that of other carbonyl compounds, which greatly limits the application of amidenol in asymmetric allyl Alkylation Catalyzed by IR In order to solve this problem, stable amidoenols came into being Up to now, stable amidenol as nucleophilic reagent has made good progress in asymmetric allylic alkylation, but the catalytic system for this kind of reaction is limited to IR and Cu CO catalytic system and PD catalytic system, and PD catalytic system can not get β - tetra substituted products On the basis of the above background research, Eric M carreira group, Federal Institute of technology, Zurich, Switzerland, reported that IR catalyzed the asymmetric allylic alkylation of 4,4 '- (ethylene-1,1-dimethyl) dimorphine with allylic carbonyl compounds, which can obtain γ, δ - Unsaturated - β - substituted morpholine amides with excellent enantioselectivity At the same time, the racemic allyl carbonyl compounds can be obtained by kinetic resolution under the catalysis of chiral ligand L1 The optically pure (s) - allyl carbonyl compounds can form (s) - γ, δ - Unsaturated - β - substituted morpholine amides (scheme1) under the action of the achiral ligand L2 Relevant research results were published in angelw Chem Int ed (DOI: 10.1002 / anie 201903090) (photo source: angelw Chem Int ed.) firstly, taking 4,4 '- (ethylene-1,1-diyl) dimorphine 2 and allyl alcohol 1 as template substrates, the nucleophiles were found to decompose easily under the catalysis of 2.5 mol% [IR (COD) Cl] 2 and 10 mol% L1 In order to overcome this problem, the author chose 4,4 '- (ethylene-1, The optimal conditions were (Table 1): 2.5 mol% [IR (COD) Cl] 2 and 10 mol% L1 ligand as catalyst, 1.3 equiv et 3N as additive, ch 2Cl 2 as solvent The reaction time was 4 hours at room temperature The yield was 47% and 98% At the same time, we can get (s) - 1 in 45% yield (picture source: angelw Chem Int ed.) under the optimal reaction conditions, the author investigated the substrate range (scheme 2) of allyl carbonyl compound 1 2-naphthyl, electron donor phenyl and heterocyclic allylic carbonyl compounds are all suitable for the reaction conditions The corresponding products of R configuration and (s) - allylic carbonyl compounds can be obtained with medium yield and excellent enantioselectivity (image source: angelw Chem Int ed.) next, the author examined the substrate range (scheme 3) of (s) - allylcarbonyl compounds 10 mol% L2 ligand is used as catalyst, other conditions are consistent with the optimal reaction conditions All the recovered substituted (s) - allylcarbonyl compounds can react with 2, and the corresponding products with s configuration can be obtained with medium to excellent yield and excellent enantioselectivity (image source: angelw Chem Int ed.) in order to verify the mechanism, the author has done a series of control experiments (scheme 4) The main product of the reaction was found to be 4 If the aromatic acyl chloride is replaced with allyl alcohol, the main product of the reaction is 5 This experiment shows that the intermediate I-3 will be preferentially generated in the reaction process, and then I-3 will react with electrophilic reagent as nucleophilic reagent (scheme 4a) Under the action of ir-l2 complex, allyl alcohol will form I-1, which can be determined by single crystal Under the standard conditions, the catalyst I-1 is equivalent to the in-situ formation of [IR (COD) Cl] 2 and complex L2 (scheme 4b) (image source: angelw Chem Int ed.) in order to prove the potential value of the reaction, the author made a series of derivative reactions (scheme 5) Through simple derivatization, morpholine amide can be converted into corresponding ketone 6, acyl silane 7 and γ - tetrasubstituted ring structure 8 with medium yield and excellent enantioselectivity At the same time, the carbonyl group of morpholine amide can be selectively reduced by selecting a suitable reducing agent to obtain compound 9 (photo source: angelw Chem Int ed.) Summary: Eric M carreira group, Federal Institute of technology, Zurich, Switzerland, reported that IR catalyzes the asymmetric allyl alkylation of 4,4 '- (ethylene-1,1-dimethyl) dimorphine with allyl carbonyl compounds, which can obtain γ, δ - Unsaturated - β - substituted morpholine amides with excellent enantioselectivity Through simple derivatization, morpholine amide can be converted into corresponding ketones, acyl silanes and amines with excellent enantioselectivity.
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