Literature DB >> 17132006

Lithium diisopropylamide solvated by hexamethylphosphoramide: substrate-dependent mechanisms for dehydrobrominations.

Yun Ma1, Antonio Ramirez, Kanwal Jit Singh, Ivan Keresztes, David B Collum.   

Abstract

Lithium diisopropylamide-mediated dehydrobrominations of exo-2-bromonorbornane, 1-bromocyclooctene, and cis-4-bromo-tert-butylcyclohexane were studied in THF solutions and THF solutions with added hexamethylphosphoramide (HMPA). Rate studies reveal a diverse array of mechanisms based on mono-, di-, and trisolvated monomers as well as triple ions. The results are contrasted with analogous eliminations in THF in the absence of HMPA.

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Year:  2006        PMID： 17132006     DOI： 10.1021/ja060964b

Source DB:  PubMed          Journal:  J Am Chem Soc        ISSN： 0002-7863            Impact factor:   15.419


  12 in total

1.  Reaction of lithium diethylamide with an alkyl bromide and alkyl benzenesulfonate: origins of alkylation, elimination, and sulfonation.

Authors:  Lekha Gupta; Antonio Ramírez; David B Collum
Journal:  J Org Chem       Date:  2010-11-16       Impact factor: 4.354

2.  Lithium Hexamethyldisilazide-Mediated Enolization of Acylated Oxazolidinones: Solvent, Cosolvent, and Isotope Effects on Competing Monomer- and Dimer-Based Pathways.

Authors:  Gabriel J Reyes-Rodríguez; Russell F Algera; David B Collum
Journal:  J Am Chem Soc       Date:  2017-01-12       Impact factor: 15.419

3.  Mechanism of Lithium Diisopropylamide-Mediated Ortholithiation of 1,4-Bis(trifluoromethyl)benzene under Nonequilibrium Conditions: Condition-Dependent Rate Limitation and Lithium Chloride-Catalyzed Inhibition.

Authors:  Jun Liang; Alexander C Hoepker; Russell F Algera; Yun Ma; David B Collum
Journal:  J Am Chem Soc       Date:  2015-05-06       Impact factor: 15.419

4.  Azaaldol condensation of a lithium enolate solvated by N,N,N',N'-tetramethylethylenediamine: dimer-based 1,2-addition to imines.

Authors:  Timothy S De Vries; Angela M Bruneau; Lara R Liou; Hariharaputhiran Subramanian; David B Collum
Journal:  J Am Chem Soc       Date:  2013-03-04       Impact factor: 15.419

5.  Sodium Diisopropylamide in N,N-Dimethylethylamine: Reactivity, Selectivity, and Synthetic Utility.

Authors:  Yun Ma; Russell F Algera; David B Collum
Journal:  J Org Chem       Date:  2016-11-02       Impact factor: 4.354

6.  1,4-addition of lithium diisopropylamide to unsaturated esters: role of rate-limiting deaggregation, autocatalysis, lithium chloride catalysis, and other mixed aggregation effects.

Authors:  Yun Ma; Alexander C Hoepker; Lekha Gupta; Marc F Faggin; David B Collum
Journal:  J Am Chem Soc       Date:  2010-11-10       Impact factor: 15.419

7.  Regioselective lithium diisopropylamide-mediated ortholithiation of 1-chloro-3-(trifluoromethyl)benzene: role of autocatalysis, lithium chloride catalysis, and reversibility.

Authors:  Alexander C Hoepker; Lekha Gupta; Yun Ma; Marc F Faggin; David B Collum
Journal:  J Am Chem Soc       Date:  2011-04-18       Impact factor: 15.419

8.  Lithium diisopropylamide-mediated reactions of imines, unsaturated esters, epoxides, and aryl carbamates: influence of hexamethylphosphoramide and ethereal cosolvents on reaction mechanisms.

Authors:  Yun Ma; David B Collum
Journal:  J Am Chem Soc       Date:  2007-11-07       Impact factor: 15.419

9.  Case for Lithium Tetramethylpiperidide-Mediated Ortholithiations: Reactivity and Mechanisms.

Authors:  Kyle A Mack; David B Collum
Journal:  J Am Chem Soc       Date:  2018-03-28       Impact factor: 15.419

10.  13C INEPT diffusion-ordered NMR spectroscopy (DOSY) with internal references.

Authors:  Deyu Li; Russell Hopson; Weibin Li; Jia Liu; Paul G Williard
Journal:  Org Lett       Date:  2008-02-06       Impact factor: 6.005
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