Enantioselective [1,3] O-to-C rearrangement: dearomatization of alkyl 2-allyloxy/benzyloxy-1/3-naphthoates catalyzed by a chiral π–Cu(ii) complex

Abstract

An asymmetric [1,3] O-to-C rearrangement of alkyl 2-allyloxy/benzyloxy-1/3-naphthoates was realized under the catalysis of a chiral π–Cu(ii) complex to produce naphthalenone derivatives bearing an all-carbon quaternary stereogenic center in good to high yield with excellent enantioselectivity. The π–cation interaction of the complex was proved by X-ray diffraction analysis.

Enantio‐ and Site‐Selective α‐Fluorination of N‐Acyl 3,5‐Dimethylpyrazoles Catalyzed by Chiral π–CuII Complexes

“…In summary, we have developed a highly enantio‐ and site‐selective α‐fluorination of N ‐acyl 3,5‐dimethylpyrazoles catalyzed by chiral π–Cu II catalysts. This new catalytic method is highly useful even compared to those described in previous reports: 1) new chiral ligands L3 and L4 have been developed, 2) the pseudo‐ Z conformation of N ‐acyl pyrazoles increases the acidity of α‐hydrogen atoms, 3) the substrate scope has been widely broadened, 4) the catalyst loading is reduced to 1.0–10 mol %, 5) the reaction is fast (1–24 h) and scalable (0.3–6.0 mmol), and 6) α‐fluorinated products are converted into the corresponding esters, secondary amides, tertiary amides, ketones, and alcohols with almost no epimerization. In addition, the π–Cu II interaction between 3‐aryl‐ l ‐alanine amide and CuX 2 has been clarified by X‐ray single‐crystal analysis, the UV absorption difference spectral analysis, and ESR analysis .…”

“…In addition, the p-Cu II interaction between 3-aryl-l-alanine amide and CuX 2 has been clarified by X-ray single-crystal analysis,t he UV absorption difference spectral analysis,and ESR analysis. [10][11][12][13][14][15][16][30][31][32][33] Thefurther application of these catalysts in other asymmetric reactions is underway.…”

“…[7] Our attention is focused on the use of p-Cu II complexes of CuX 2 with 3-aryl-l-alanine-derived amides as asymmetric catalysts.S ince 2006, we have reported several p-Cu II complex-catalyzed enantioselective nucleophilic addition re-actions to a,b-unsaturated N-acyl pyrazoles,w hich are appropriate as electrophiles because of the relatively low pK a values of N-acyl pyrazoles [8,9] due to the electron deficiencyo ft he pyrazole moiety. [10][11][12][13][14][15][16] In addition, several groups have reported that N-acyl pyrazoles are useful as amide pronucleophiles for the same reason. [17][18][19][20] Against this background, here we describe the development of ah ighly efficient enantioselective a-fluorination of N-acyl 3,5-dimethylpyrazoles catalyzed by chiral p-Cu II complexes.…”

“…Our attention is focused on the use of π–Cu II complexes of CuX 2 with 3‐aryl‐ l ‐alanine‐derived amides as asymmetric catalysts. Since 2006, we have reported several π–Cu II complex‐catalyzed enantioselective nucleophilic addition reactions to α,β‐unsaturated N ‐acyl pyrazoles, which are appropriate as electrophiles because of the relatively low p K a values of N ‐acyl pyrazoles due to the electron deficiency of the pyrazole moiety . In addition, several groups have reported that N ‐acyl pyrazoles are useful as amide pronucleophiles for the same reason .…”

Tandem Insertion–[1,3]‐Rearrangement: Highly Enantioselective Construction of α‐Aminoketones

“…In 2018, Patil and co‐workers demonstrated an early example of chiral phosphoric acid catalyzed enantioselective [1,3] O‐to‐C rearrangement of aryl substituted oxindole ethers to generate 3‐phenol substituted oxindole derivatives (Scheme a) . Recently, the group of Ishihara developed a chiral Cu(II) complex promoted asymmetric rearrangement of naphthol‐derived vinyl ethers which yielded 1‐allylnaphthalenone derivatives (Scheme b) . Despite these significant advances, the substrates are mainly limited to aryl ethers which were prepared in advance.…”