Synthesis of β-Chloroimines

Stable synthetic equivalents of N-unsubstituted imines: Part 1. Synthesis

“…The resultant water is removed using azeotropic distillation [116] or molecular sieves (4 Å) [113], P 2 O 5 /SiO 2 [117], MgSO 4 [118,119], or TiCl 4 [119] that also catalyze the reaction as Lewis acids. Sometimes, the reaction is carried out on cooling in the absence of catalyst and dehydrating agent [109].…”

Product Class 7: Imines

“…[122] Common solvents used in this method are diethyl ether, benzene, [123] and toluene. This method allows the use of different functionalized carbonyl components ranging from AE-chloro ketones ( Table 2, entry 10), [124,125] 1-aminoalkyl chloromethyl ketones ( Table 2, entry 12), [126] AE,AE-dichloro ketones, [127] AE-bromo ketones ( Table 2, entry 11), [124,125,128] â-chloro ketones and â-chloro aldehydes ( Table 2, entries 3-8), [129] ª-chloro ketones, [130] ª-chloro-AE-oxo carboxylic esters, [131] ä-chloro aldehydes, [132] AE-oxo acetals, [133] and AE-sulfenylated aldehydes. [134] 1,2-Diimines can be synthesized in a similar manner from 1,2-diketones and amines.…”

“…[139] From a mechanistic point of view it is assumed that the intermediate AE-azido imine 25 expels molecular nitrogen via its enamine and hence generates an N-unsubstituted imine, which forms the 1,2-diimine 26 by ammonia-isopropylamine exchange. â-Chloro Imines; General Procedure: [129] To a vigorously stirred, ice-cooled soln of the â-chloro carbonyl compound (0.1 mol) in dry Et 2 O (10% soln, w/v) and the primary amine (0.4 mol for volatile amines or 0.3 mol for lessvolatile amines) was added dropwise a soln of TiCl 4 (0.055-0.060 mol) in pentane (20 mL) at such a rate to ensure a smooth reaction (exothermic). Afterwards, the mixture was stirred at rt or refluxed for several hours depending upon the amine and the carbonyl compound.…”

“…[147] N-Aryl Ketimines; General Procedure: [141] To a mixture of a ketone (0.10 mol) and an aromatic amine (0.12 mol) in benzene (CAU- Magnesium sulfate is often used as a drying agent and as a Lewis acid in aldimine syntheses. This way functionalized imines such as N-benzyl-AE-chloro aldimines, [148] â-chloro aldimines, [129] N-benzyl-N-(5-chloro-2,2-dimethylpentylidene)amine, [149] AE,â-unsaturated aldimines, [150] and â-oxo aldehydes, [151] as well as imines such as cyclopropanecarbaldimines, [152] N-benzylidene-N-homoallylamines, [153] and simple aliphatic aldimines, [154][155][156][157] are available. Alkylammonium salts can also be condensed this way, provided that 1 equivalent of triethylamine is added to the reaction mixture.…”

“…Synthesis of N-Substituted Imines from Primary Amines and Aldehydes or Ketones Activated by Titanium(IV) Chloride[121,124,126,129,138] …”