Chiral lithium amides on polymer support — Synthesis and use in deprotonation of ketones

2006 ◽  
Vol 84 (2) ◽  
pp. 257-268 ◽  
Author(s):  
Marek Majewski ◽  
Agnieszka Ulaczyk-Lesanko ◽  
Fan Wang
Keyword(s):  
Ring Opening ◽  
Secondary Amines ◽  
Polymer Support ◽  
Lithium Amides ◽  
Polystyrene Support ◽  
Merrifield Resin ◽  
Polymer Supported

A number of chiral secondary amines attached to Merrifield resin or to noncrosslinked (soluble) polystyrene support were synthesized. The corresponding lithium amides, generated from these amines by treatment with BuLi, react with tropinone, a model symmetrical ketone, to give the corresponding enolates enantioselectively (ee up to 75%). The enolates were trapped either as the corresponding aldol adducts by a reaction with benzaldehyde or as ring-opening products in a reaction with a chloroformate.Key words: chiral lithium amides, polymer-supported reagents, deprotonation, enolates, tropinone.

Stereoselective deprotonation of tropinone and reactions of tropinone lithium enolate

1992 ◽  
Vol 70 (10) ◽  
pp. 2618-2626 ◽  
Author(s):  
Marek Majewski ◽  
Guo-Zhu Zheng
Keyword(s):  
Acetic Acid ◽  
Ring Opening ◽  
Aldol Reaction ◽  
Ethyl Chloroformate ◽  
Lithium Diisopropylamide ◽  
Silver Acetate ◽  
Lithium Amides ◽  
Lithium Enolate ◽  
The Absolute ◽  
Absolute Stereochemistry

Tropinone (6) was deprotonated with lithium diisopropylamide and with chiral lithium amides (18–24) and the resulting enolates (two enantiomers) were treated with electrophiles. The aldol reaction with benzaldehyde and deuteration were both diastereoselective. The former yielded only one isomer (exo, anti) of the aldol 8a; the latter proceeded from the exo face. This selectivity permitted us to probe the deprotonation of tropinone with lithium amides; it was concluded that the reaction involves predominantly the exo axial protons. The reaction of tropinone enolate with ethyl chloroformate led, via a ring opening, to the cycloheptenone derivative 9. The reaction with methyl cyanoformate yielded, in the presence of silver acetate and acetic acid, the β-ketoester 8b; however, in the absence of these additives, and especially when 12-crown-4 was added to the enolate, a ring opening leading to the pyrrolidine derivative 10 occurred instead. Deprotonation of tropinone with chiral lithium amides proceeded with modest enantioselectivity. A synthesis of non-racemic anhydroecgonine via this strategy allowed establishing the absolute stereochemistry of deprotonation.

Direct ring-opening of lactide with amines: application to the organo-catalyzed preparation of amide end-capped PLA and to the removal of residual lactide from PLA samples

2015 ◽  
Vol 6 (6) ◽  
pp. 989-997 ◽  
Author(s):  
Aurélie Alba ◽  
Olivier Thillaye du Boullay ◽  
Blanca Martin-Vaca ◽  
Didier Bourissou
Keyword(s):  
Ring Opening ◽  
Secondary Amines ◽  
Primary And Secondary Amines

Spontaneous ring-opening of lactide by primary and secondary amines has been applied to the preparation of well-defined amide end-capped PLA and to the removal of unreacted lactide from PLA samples.

scholarly journals Rhodium(III)-Catalyzed Three-Component 1,2-Diamination of Unactivated Terminal Alkenes

Synthesis ◽  
2019 ◽  
Vol 52 (08) ◽  
pp. 1247-1252 ◽  
Author(s):  
Sumin Lee ◽  
Young Jin Jang ◽  
Erik J. T. Phipps ◽  
Honghui Lei ◽  
Tomislav Rovis
Keyword(s):  
Good Yield ◽  
Ring Opening ◽  
Secondary Amines ◽  
One Pot ◽  
Rapid Access ◽  
Primary And Secondary Amines ◽  
Terminal Alkenes ◽  
Broad Array ◽  
Vicinal Diamines

We report a three-component diamination of simple unactivated alkenes using an electrophilic nitrene source and amine nucleo­philes. The reaction provides rapid access to 1,2-vicinal diamines from terminal alkenes through a one-pot protocol. The transformation proceeds smoothly with excellent tolerance for a broad array of primary and secondary amines, affording the desired products in good yield and regioselectivity. The mechanism is proposed to proceed through a Rh(III)-catalyzed aziridination of alkenes with subsequent ring opening by primary or secondary amines.

1H-1,3-Diazepines and Ketenimines from Cyanotetrazolopyridines

2008 ◽  
Vol 61 (8) ◽  
pp. 592 ◽  
Author(s):  
Chris Addicott ◽  
Curt Wentrup
Keyword(s):  
Infrared Spectra ◽  
Ring Opening ◽  
Ring Expansion ◽  
Secondary Amines ◽  
Argon Matrix ◽  
The Matrix ◽  
Nitrogen Elimination ◽  
Isolated Species

Cyano-substituted tetrazolo[1,5-a]pyridines/2-azidopyridines 8T and 15T undergo thermal ring opening to the azides 8A and 15A. Solution photolysis causes nitrogen elimination and ring expansion to 1,3-diazacyclohepta-1,2,4,6-tetraenes 10 and 17, which react with alcohols to afford 2-alkoxy-1H-1,3-diazepines, with secondary amines to 2-dialkylamino-5H-1,3-diazepines, and with water to 1,3-diazepin-2-ones (12–14, 19, 21). Argon matrix photolysis of the azides affords the diazacycloheptatetraenes 10 and 17 as principal products together with ring-opened dicyanovinylketenimines 11 and 18. The matrix-isolated species were identified on the basis of comparison of the infrared spectra with those calculated at the B3LYP/6–31+G* level.

Asymmetric ring-opening reactions of azabenzonorbornadienes through transfer hydrogenation using secondary amines as hydrogen sources: tuning of absolute configuration by acids

2018 ◽  
Vol 5 (21) ◽  
pp. 3077-3082 ◽  
Author(s):  
Dongdong Pu ◽  
Yongyun Zhou ◽  
Fan Yang ◽  
Guoli Shen ◽  
Yang Gao ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Ring Opening ◽  
Transfer Hydrogenation ◽  
Secondary Amines ◽  
Ring Opening Reactions ◽  
Asymmetric Ring Opening

Switching of absolute configuration by acids during palladium and silver co-catalyzed transfer hydrogenation of heterobicycles by secondary amines.

Polymer-supported ceric(IV) catalyst: 1. Catalytic ring opening of epoxides

Polymer ◽  
1993 ◽  
Vol 34 (9) ◽  
pp. 2011-2013 ◽  
Author(s):  
B. Tamami ◽  
N. Iranpoor ◽  
M.A.Karimi Zarchi
Keyword(s):  
Ring Opening ◽  
Ring Opening Of Epoxides ◽  
Polymer Supported

scholarly journals Ring Opening of Donor–Acceptor Cyclopropanes with N-Nucleo­philes

Synthesis ◽  
2017 ◽  
Vol 49 (14) ◽  
pp. 3035-3068 ◽  
Author(s):  
Ekaterina Budynina ◽  
Konstantin Ivanov ◽  
Ivan Sorokin ◽  
Mikhail Melnikov
Keyword(s):  
Ring Opening ◽  
Building Blocks ◽  
Simple Approach ◽  
Secondary Amines ◽  
Primary Amines ◽  
Pyrrole Derivatives ◽  
Heteroaromatic Compounds ◽  
Azide Ion ◽  
Ring Opening Reactions ◽  
Donor Acceptor

Ring opening of donor–acceptor cyclopropanes with various N-nucleophiles provides a simple approach to 1,3-functionalized compounds that are useful building blocks in organic synthesis, especially in assembling various N-heterocycles, including natural products. In this review, ring-opening reactions of donor–acceptor cyclopropanes with amines, amides, hydrazines, N-heterocycles, nitriles, and the azide ion are summarized.1 Introduction2 Ring Opening with Amines3 Ring Opening with Amines Accompanied by Secondary Processes Involving the N-Center3.1 Reactions of Cyclopropane-1,1-diesters with Primary and Secondary Amines3.1.1 Synthesis of γ-Lactams3.1.2 Synthesis of Pyrroloisoxazolidines and -pyrazolidines3.1.3 Synthesis of Piperidines3.1.4 Synthesis of Azetidine and Quinoline Derivatives3.2 Reactions of Ketocyclopropanes with Primary Amines: Synthesis of Pyrrole Derivatives3.3 Reactions of Сyclopropane-1,1-dicarbonitriles with Primary Amines: Synthesis of Pyrrole Derivatives4 Ring Opening with Tertiary Aliphatic Amines5 Ring Opening with Amides6 Ring Opening with Hydrazines7 Ring Opening with N-Heteroaromatic Compounds7.1 Ring Opening with Pyridines7.2 Ring Opening with Indoles7.3 Ring Opening with Di- and Triazoles7.4 Ring Opening with Pyrimidines8 Ring Opening with Nitriles (Ritter Reaction)9 Ring Opening with the Azide Ion10 Summary

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