Asymmetric Synthesis of Dihydrofurans via Organocatalytic Domino Michael-Alkylation Reaction

2015 ◽  
Vol 357 (6) ◽  
pp. 1305-1310 ◽  
Author(s):  
Juhua Feng ◽  
Lili Lin ◽  
Kunru Yu ◽  
Xiaohua Liu ◽  
Xiaoming Feng
Keyword(s):  
Asymmetric Synthesis ◽  
Alkylation Reaction

A Concise and Modular Three-Step Synthesis of (S)-Verapamil using an Enantioselective Rhodium-Catalyzed Allylic Alkylation Reaction

Synthesis ◽  
2020 ◽  
Vol 52 (15) ◽  
pp. 2185-2189 ◽  
Author(s):  
P. Andrew Evans ◽  
Mai-Jan Tom ◽  
Ben W. H. Turnbull
Keyword(s):  
Calcium Channel ◽  
Asymmetric Synthesis ◽  
Channel Blocker ◽  
Alkylation Reaction ◽  
Allylic Alkylation ◽  
Efficient Synthesis ◽  
Terminal Olefin ◽  
Bioactive Agents ◽  
Quaternary Stereocenter ◽  
Modular Nature

A concise and modular asymmetric synthesis of the calcium channel blocker (S)-verapamil is described. This approach employs an enantioselective rhodium-catalyzed allylic alkylation reaction between an α-isopropyl-substituted benzylic nitrile and allyl benzoate to construct the challenging acyclic quaternary stereocenter. The terminal olefin then serves as a convenient synthetic handle for a hydroamination to introduce the phenethylamine moiety, furnishing (S)-verapamil in three steps and 55% overall yield, thus providing the most efficient synthesis of this important pharmaceutical reported to date. Furthermore, given the modular nature of the synthesis, it can be readily modified to prepare structurally related bioactive agents.

ChemInform Abstract: Asymmetric Synthesis of (+)- and (-)-Coniines and (-)-Sedamine by Diastereoselective Alkylation Reaction of Ethoxypiperidinone.

ChemInform ◽  
2010 ◽  
Vol 22 (9) ◽  
pp. no-no
Author(s):  
T. KIGUCHI ◽  
Y. NAKAZONO ◽  
S. KOTERA ◽  
I. NINOMIYA ◽  
T. NAITO
Keyword(s):  
Asymmetric Synthesis ◽  
Alkylation Reaction

Ephedrines as Chiral Auxiliaries in Enantioselective Alkylation Reactions of Acyl Ephedrine Amides and Esters: A Review

2018 ◽  
Vol 15 (1) ◽  
pp. 38-83 ◽  
Author(s):  
Alejandro Cruz ◽  
Itzia I. Padilla-Martínez ◽  
Maria E. Bautista-Ramirez
Keyword(s):  
Asymmetric Synthesis ◽  
Bond Formation ◽  
Alkyl Halides ◽  
Aldol Reactions ◽  
Alkylation Reaction ◽  
Chiral Auxiliaries ◽  
Asymmetric Alkylation ◽  
Chiral Compounds ◽  
High Yields ◽  
Alkylation Reactions

Background: In modern chemistry, the asymmetric synthesis for the preparation of high purity chiral compounds to be used as pharmaceuticals or additives in foods have been of capital importance. Chiral auxiliary reagents are used to control the stereochemistry of the reaction in the generation of new chiral compounds, in this context, Ephedra compounds (ephedrines and pseudoephedrines) and some of their derivatives have been broadly used as chiral ligands in catalysis or chiral inductors in asymmetric synthesis. Objective: This review focuses on recent progress in the use of ephedra compounds and their N-substituted derivatives as chiral auxiliaries in the area of asymmetric synthesis, via the alkylation reaction of the enolates derived from their corresponding N-Acyl or O-Acyl derivatives, in the C-C bond formation. Conclusion: A vast amount of work has been done about the use of ephedra compounds in asymmetric synthesis area, in general, it was found that pseudoephedrines are much more effective than ephedrines and are preferred as chiral auxiliaries in the asymmetric alkylation of the corresponding N-acyl amides or O-Acyl esters. Alkylation with alkyl halides requires the use of more than 4 equivalents of LiCl to accelerate the alkylation rate and to complete the reaction without effecting the diastereoselectivity of the process. In contrast, the use of secondary alkyl halides was found to make the reaction very slow. Furthermore, a lot of work about the alkylation reaction in the opening of epoxides and aziridines, aldolic condensation, Manich reaction, addition of nucleophiles to α,β-unsaturated ephedrine amides and Michael additions have been demonstrated to be effective in the C-C bond formation. The aldol reaction of chiral enolates, proceeds with decreasing yields and enantioselectivities as the steric demand of the α-R of ephedrine amides and the size of carbonyl compound increase. In addition, the use of branched groups on N,N-disubstituted norephedrine esters is highly recommended in the aldol reactions of aromatic and aliphatic aldehydes.In the case of N-Acyl or O-Acyl ephedrines supported on polymers, the reaction proceed with good enantioselectivities but low yields, the enantioselectivities are goods but the yields are low. In general, the removal step of the auxiliary proceeds with low to high yields but without epimerization.

Asymmetric Synthesis of 2,3-Dihydrofurans via Squaramide Catalyzed Michael-Alkylation Reaction

2021 ◽  
Vol 19 ◽  
Author(s):  
Zhi-Wei Ma ◽  
Chuan-Chuan Wang ◽  
Xiao-Pei Chen ◽  
Bin Sun ◽  
Jing-Chao Tao ◽  
...  
Keyword(s):  
Asymmetric Synthesis ◽  
Asymmetric Catalysis ◽  
Tertiary Amine ◽  
Alkylation Reaction

Abstract: Asymmetric Catalysis, Dihydrofuran, Michael-Alkylation Reaction, Tertiary Amine-Squaramide, Organocatalysis, α-Bromonitroalkene

Synthetic Studies toward Tubiferal A: Asymmetric Synthesis of a Model ABC-ring Compound

Synlett ◽  
2021 ◽  
Author(s):  
Yuki Yukutake ◽  
Takahiro Hiramatsu ◽  
Ryusei Itoh ◽  
Kazutada Ikeuchi ◽  
Takahiro Suzuki ◽  
...  
Keyword(s):  
Asymmetric Synthesis ◽  
Claisen Rearrangement ◽  
Ring System ◽  
Alkylation Reaction ◽  
Ring Model ◽  
Stereoselective Addition ◽  
Stereogenic Centers ◽  
Rearrangement Reaction ◽  
Synthetic Studies ◽  
Ab Ring

Synthetic studies on an ABC-ring model of Tubiferal A, a triterpenoid isolated from the fruit bodies of the Tubifera dimorphotheca myxomycete, are described. The stereogenic centers at the angular positions were constructed through the stereoselective addition of a C-ring allylborane followed by an Eschenmoser–Claisen rearrangement reaction prior to the formation of the AB-ring system by a double intramolecular alkylation reaction of a dichloro nitrile intermediate.

ChemInform Abstract: Asymmetric Synthesis of Dihydrofurans via Organocatalytic Domino Michael-Alkylation Reaction.

ChemInform ◽  
2015 ◽  
Vol 46 (34) ◽  
pp. no-no
Author(s):  
Juhua Feng ◽  
Lili Lin ◽  
Kunru Yu ◽  
Xiaohua Liu ◽  
Xiaoming Feng
Keyword(s):  
Asymmetric Synthesis ◽  
Alkylation Reaction

scholarly journals Convenient Asymmetric Synthesis of Fmoc-(S)-6,6,6-Trifluoro-Norleucine

Symmetry ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 578 ◽  
Author(s):  
Mei ◽  
Yin ◽  
Miwa ◽  
Moriwaki ◽  
Abe ◽  
...  
Keyword(s):  
Amino Acid ◽  
Asymmetric Synthesis ◽  
Total Yield ◽  
Enantiomeric Purity ◽  
Alkylation Reaction ◽  
Target Amino Acid

In this work we report a convenient asymmetric synthesis of Fmoc-(S)-6,6,6-trifluoro-norleucine via alkylation reaction of chiral glycine equivalent. The target amino acid of 99% enantiomeric purity was prepared with 82.4% total yield (three steps).

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