Asymmetric N-aminoalkylation of 3-substituted indoles by N-protected N,O-acetals: an access to chiral propargyl aminals

2020 ◽  
Vol 18 (22) ◽  
pp. 4169-4173
Author(s):  
Junxian Yang ◽  
Zeyuan He ◽  
Liang Hong ◽  
Wangsheng Sun ◽  
Rui Wang
Keyword(s):  
Phosphoric Acid ◽  
Acid Catalyst ◽  
Mild Conditions

A direct enantioselective N1 aminoalkylation of 3-substituted indoles is efficiently catalyzed by a phosphoric acid catalyst under mild conditions, which could be applied to the modification of tryptophan containing oligopeptides.

The Highly Enantioselective Addition of Indoles toN-Acyl Imines with Use of a Chiral Phosphoric Acid Catalyst

2007 ◽  
Vol 9 (14) ◽  
pp. 2609-2611 ◽  
Author(s):  
Gerald B. Rowland ◽  
Emily B. Rowland ◽  
Yuxue Liang ◽  
Jason A. Perman ◽  
Jon C. Antilla
Keyword(s):  
Phosphoric Acid ◽  
Acid Catalyst ◽  
Chiral Phosphoric Acid ◽  
Enantioselective Addition

Refining Gasoline with Solid Phosphoric Acid Catalyst

1938 ◽  
Vol 30 (11) ◽  
pp. 1316-1317 ◽  
Author(s):  
V. N. Ipatieft ◽  
B. B. Corson
Keyword(s):  
Phosphoric Acid ◽  
Acid Catalyst

scholarly journals QM/MM study on the enantioselectivity of spiroacetalization catalysed by an imidodiphosphoric acid catalyst: how confinement works

2016 ◽  
Vol 14 (11) ◽  
pp. 3031-3039 ◽  
Author(s):  
Luis Simón ◽  
Robert S. Paton
Keyword(s):  
Phosphoric Acid ◽  
Acid Catalyst ◽  
Acid Catalysts ◽  
Chiral Phosphoric Acid

An explanation of why confined imidodiphosphoric acid catalyst succeeds where other chiral phosphoric acid catalysts fail.

scholarly journals Organocatalytic enantioselective dearomatization of thiophenes by 1,10-conjugate addition of indole imine methides

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xingguang Li ◽  
Meng Duan ◽  
Peiyuan Yu ◽  
K. N. Houk ◽  
Jianwei Sun
Keyword(s):  
Hydrogen Bonding ◽  
Phosphoric Acid ◽  
Nucleophilic Addition ◽  
Acid Catalysis ◽  
Conjugate Addition ◽  
Mild Conditions ◽  
Rapid Construction ◽  
Chiral Phosphoric Acid ◽  
Cyclic Molecules ◽  
Selectivity Control

AbstractCatalytic asymmetric dearomatization (CADA) is a powerful tool for the rapid construction of diverse chiral cyclic molecules from cheap and easily available arenes. This work reports an organocatalytic enantioselective dearomatization of substituted thiophenes in the context of a rare remote asymmetric 1,10-conjugate addition. By suitable stabilization of the thiophenyl carbocation with an indole motif in the form of indole imine methide, excellent remote chemo-, regio-, and stereocontrol in the nucleophilic addition can be achieved with chiral phosphoric acid catalysis under mild conditions. This protocol can be successfully extended to the asymmetric dearomatization of other heteroarenes including selenophenes and furans. Control experiments and DFT calculations demonstrate a possible pathway in which hydrogen bonding plays an important role in selectivity control.

Enantioselective Approaches to 3,4-Annulated Indoles Using Organocatalytic Domino Reactions

Synlett ◽  
2017 ◽  
Vol 28 (13) ◽  
pp. 1530-1543 ◽  
Author(s):  
Mariafrancesca Fochi ◽  
Luca Bernardi ◽  
Lorenzo Caruana
Keyword(s):  
Phosphoric Acid ◽  
Reaction Pathway ◽  
Ergot Alkaloids ◽  
Acid Catalyst ◽  
Secondary Amines ◽  
Domino Reactions ◽  
Structural Framework ◽  
Unique Reaction ◽  
Iminium Ions ◽  
Nitronic Acid

Organocatalytic domino reactions of 4-substituted indoles are summarized in this account. Two reactions have been developed, one with enals, activated by secondary amine catalysts via iminium ions, and one with nitroethene, using a phosphoric acid catalyst. Both reactions required solving the challenge posed by the very low nucleo­philicity of the indole substrates, which bear an electron-withdrawing Michael acceptor at C4. DFT calculations were used to shed light on the unique reaction pathway followed by the phosphoric acid catalyzed transformation, wherein a bicoordinated nitronic acid intermediate was found to evolve preferentially through an intramolecular nitro-Michael reaction, instead of the common tautomerization pathway. These reactions provide new and efficient entries to 3,4-ring-fused indoles in dia­stereo- and enantioenriched form. In more detail, the structures obtained feature a 1,3,4,5-tetrahydrobenzo[cd]indole core, which is present in the structural framework of ergot alkaloids. Indeed, the preparation of an intermediate previously used in ergot alkaloid (6,7-secoagroclavine) synthesis was possible from one of the catalytic adducts.1 Introduction2 Reactions of 4-Substituted Indoles with α,β-Unsaturated Aldehydes Catalyzed by Secondary Amines3 Reactions of 4-Substituted Indoles with Nitroethene Catalyzed by Brønsted Acids4 Conclusion

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