Synthetically important alkali-metal-utility amides: lithium, sodium and potassium hexamethyldisilazides, diisopropylamides and tetramethylpiperidides

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Abstract

Most synthetic chemists will have at some point utilized a sterically demanding secondary amide (R2N−). The three most important examples, lithium 1,1,1,3,3,3-hexamethyldisilazide (LiHMDS), lithium diisopropylamide (LiDA), and lithium 2,2,6,6-tetramethylpiperidide (LiTMP)—the “utility amides”—have long been indispensible particularly for lithiation (Li-H exchange) reactions. Like organolithium compounds, they exhibit aggregation phenomena and strong Lewis acidity, and thus appear in distinct forms depending on the solvents employed. The structural chemistry of these compounds as well as their sodium and potassium congeners are described in the absence or in the presence of the most synthetically significant donor solvents tetrahydrofuran (THF) and N,N,N’,N’-tetramethylethylenediamine (TMEDA) or closely related solvents. Examples of hetero-alkali-metal amides, an increasingly important composition because of the recent escalation of interest in mixed-metal synergic effects, are also included.
LanguageEnglish
Pages11470–11487
Number of pages18
JournalAngewandte Chemie International Edition
Volume52
Issue number44
DOIs
Publication statusPublished - 25 Oct 2013

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Alkali Metals
Lithium
Amides
Potassium
Sodium
Potassium Compounds
Sodium Compounds
Acidity
Agglomeration
Metals
Chemical analysis
hexamethylsilazane

Keywords

  • alkali metals
  • heterometallic compounds
  • molecular structure
  • secondary amide
  • solution state

Cite this

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title = "Synthetically important alkali-metal-utility amides: lithium, sodium and potassium hexamethyldisilazides, diisopropylamides and tetramethylpiperidides",
abstract = "Most synthetic chemists will have at some point utilized a sterically demanding secondary amide (R2N−). The three most important examples, lithium 1,1,1,3,3,3-hexamethyldisilazide (LiHMDS), lithium diisopropylamide (LiDA), and lithium 2,2,6,6-tetramethylpiperidide (LiTMP)—the “utility amides”—have long been indispensible particularly for lithiation (Li-H exchange) reactions. Like organolithium compounds, they exhibit aggregation phenomena and strong Lewis acidity, and thus appear in distinct forms depending on the solvents employed. The structural chemistry of these compounds as well as their sodium and potassium congeners are described in the absence or in the presence of the most synthetically significant donor solvents tetrahydrofuran (THF) and N,N,N’,N’-tetramethylethylenediamine (TMEDA) or closely related solvents. Examples of hetero-alkali-metal amides, an increasingly important composition because of the recent escalation of interest in mixed-metal synergic effects, are also included.",
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author = "Mulvey, {Robert E.} and Robertson, {Stuart D.}",
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T1 - Synthetically important alkali-metal-utility amides

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AU - Mulvey, Robert E.

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Y1 - 2013/10/25

N2 - Most synthetic chemists will have at some point utilized a sterically demanding secondary amide (R2N−). The three most important examples, lithium 1,1,1,3,3,3-hexamethyldisilazide (LiHMDS), lithium diisopropylamide (LiDA), and lithium 2,2,6,6-tetramethylpiperidide (LiTMP)—the “utility amides”—have long been indispensible particularly for lithiation (Li-H exchange) reactions. Like organolithium compounds, they exhibit aggregation phenomena and strong Lewis acidity, and thus appear in distinct forms depending on the solvents employed. The structural chemistry of these compounds as well as their sodium and potassium congeners are described in the absence or in the presence of the most synthetically significant donor solvents tetrahydrofuran (THF) and N,N,N’,N’-tetramethylethylenediamine (TMEDA) or closely related solvents. Examples of hetero-alkali-metal amides, an increasingly important composition because of the recent escalation of interest in mixed-metal synergic effects, are also included.

AB - Most synthetic chemists will have at some point utilized a sterically demanding secondary amide (R2N−). The three most important examples, lithium 1,1,1,3,3,3-hexamethyldisilazide (LiHMDS), lithium diisopropylamide (LiDA), and lithium 2,2,6,6-tetramethylpiperidide (LiTMP)—the “utility amides”—have long been indispensible particularly for lithiation (Li-H exchange) reactions. Like organolithium compounds, they exhibit aggregation phenomena and strong Lewis acidity, and thus appear in distinct forms depending on the solvents employed. The structural chemistry of these compounds as well as their sodium and potassium congeners are described in the absence or in the presence of the most synthetically significant donor solvents tetrahydrofuran (THF) and N,N,N’,N’-tetramethylethylenediamine (TMEDA) or closely related solvents. Examples of hetero-alkali-metal amides, an increasingly important composition because of the recent escalation of interest in mixed-metal synergic effects, are also included.

KW - alkali metals

KW - heterometallic compounds

KW - molecular structure

KW - secondary amide

KW - solution state

UR - http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291521-3773

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