A new high-loading water-soluble scavenger for anhydrides, acid chlorides and isocyanates

Quaternary Ammonium‐Supported Scavenger Reagents for Acids and Electrophiles

“…[15] The progress of the methylation reaction was monitored by reversed-phase high-pressure liquid chromatography. This reaction was completed within 3 d with a four-fold excess of methyl iodide in a sealed reaction vessel.…”

“…Detailed experimental procedures relating to synthesis and use of TAMA-Cl have been published previously. [15] Boc-Protected α,αЈ-Bis{2-[bis(2-aminoethyl)amino]ethylamino}-pxylene 5: 1,4-Bis(chloromethyl)benzene (1.0 g, 5.7 mmol) was added to a solution of tris(2-aminoethyl)amine (5.1 mL, 34.2 mmol) in dichloromethane (2 mL). The reaction mixture was stirred for 24 h at room temperature, then DMAP (70 mg, 0.57 mmol) and Boc 2 O (24.6 g, 113 mmol) were added at 0°C.…”

Solution-Phase Synthesis of a Library of Biaryl Amides Using Girard's Reagent T as an Acid Chloride Scavenger

“…5 More recently, a water-soluble quarternary ammonium salt bearing three amino functional groups was used to remove electrophiles. 6 Other approaches utilizing polymer-supported reagents or resins have also been reported. 1b,c Suto found ion-exchange resins were useful as reagents and scavengers in syntheses.…”

“…A small amino acid, potassium sarcosinate, has been used as a quencher to remove excess electrophiles by generating water-soluble byproducts . More recently, a water-soluble quarternary ammonium salt bearing three amino functional groups was used to remove electrophiles 1b,c Suto found ion-exchange resins were useful as reagents and scavengers in syntheses …”

A Practical, Water‐Soluble, Ionic Scavenger for the Solution‐Phase Syntheses of Amides

“…Although several high-loading solid scavenger reagents have been developed, they suffer from slow exchange at the solid -liquid interface [3]. An efficient solution to these problems is replacement of the polymer-supported scavenger with smallmolecule reagents such as Girard's reagent T [4], N-methyltris(2-aminoethyl)amine [5], N-Boc-iminodiacetic anhydride [6], and potassium sarcosinate [7] to generate water-soluble byproducts, which can be separated, together with the excess scavengers, from the products by liquid -liquid extraction.Recently, Song and co-workers [8] reported an amino-functionalized ionic liquid, i.e., 1-aminoethyl-3-methylimidazolium hexafluorophosphate ([2-aemim] [PF 6 ]), as an electrophile scavenger for solution-phase synthesis; the scavenging products were separated by extraction with the ionic liquid [bmim] [PF 6 ].Herein, we describe the application of the practical, ionic, water-soluble scavenger 1-(2-aminoethyl)pyridinium bromide (1) for the solution-phase synthesis of libraries of amides and sulfonamides. …”