From Gabriel synthesis

Hauquier, R, N. Debou, S. Palacin, and B. Jousselme. Amino functionalized thin films prepared from Gabriel synthesis applied on electrografted diazonium salts. J. Electroanal. Chem. 677-680, 2012 127-132. 

Chapter IV. a-Chloromethylnaphthalene (IV,23) benzylamine (Gabriel synthesis) (IV,39) i r.N -dialkylanilines (from amines and trialkyl orthophosphates) (IV,42) a-naphthaldehyde (Sommelet reaction) (IV,120) a-phenyl-cinnamic acid (Perkin reaction using triethylamine) (IV,124) p-nitrostyrene (IV,129) p-bromonaphthalene and p naphthoic acid (from 2 naphthylamine-1 -sulphonic acid) (IV,62 and IV,164) diphenic acid (from phenanthrene) (IV,165). 

Ethyleneimine was fkst piepaied commeicially in 1938 from 2-chloioethylaniine and NaOH by a modified Gabriel synthesis (21). 

The sulphonyl chloride 23 is proposed as a protecting group for the Gabriel synthesis of secondary amines from primary amines. At the deprotecting stage, carbon-sulphur bond cleavage is achieved using zinc and acid as the electron source [109]. 

The Gabriel synthesis of amines uses potassium phthalimide (prepared from the reaction of phthalimide with potassium hydroxide). The structure and preparation of potassium phthalimide is shown in Figure 13-13. The extensive conjugation (resonance) makes the ion very stable. An example of the Gabriel synthesis is in Figure 13-14. (The N2H4 reactant is hydrazine.) The Gabriel synthesis employs an 8, 2 mechanism, so it works best on primary alkyl halides and less well on secondary alkyl halides. It doesn t work on tertiary alkyl halides or aryl halides. 

Primary amines can be prepared from alkyl halides by 0-44, by 0-63, by 0-61 followed by reduction of the azide (9-53), or by the Gabriel synthesis (0-58). 

A. The Oalrid and. Wenker Reactions The preparation of an aziridino derivative is most frequently accomplished in a two-step synthesis from a suitably substituted 0-aminn alcohol. When the reaction is carried out via the /MialGabriel synthesis (Eq. 1). in honor of the discoverer of the prototype reaction. A convenient modification of this sequence, called the Wenker synthesis (Eq, 2), was published in 1936" and almost simultaneously reported independently in the patent literature."4- SR This involves the conversion of the amino alcohol into tb 0-amino hydrogen auifete (which undoubtedly exists as the zwitterion)... 

SAMPLE SOLUTION (a) The Gabriel synthesis is limited to preparation of amines of the type RCH2NH2, that is, primary alkylamines in which the amino group is bonded to a primary carbon. Butylamine may be prepared from butyl bromide by this method. 

The success of the Gabriel synthesis depends on N-alkylation being favored over O-alkylation and SN2 being favored over E2. Polar, aprotic solvents such as methylsulfinylmethane, (CH3)2SO, are useful for the Gabriel synthesis. Hydrolysis of the alkylation product often is difficult and amide interchange (analogous to ester interchange, Section 18-7A) with hydrazine can be an effective way to free the amine from the imide. 

Aminomethylbenzo[6]thiophene556 and its 5-hydroxy derivative 562 may be prepared by a Gabriel synthesis from the corresponding... 

An alternative reagent equivalent for the amide anion synthon is the potassium salt of phthalimide which can only react with one molecular proportion of alkyl halide. The resulting JV-alkylphthalimide is then cleaved to the primary amine (the Gabriel synthesis). The preliminary preparation of potassium phthalimide (from a solution of phthalimide in absolute ethanol and potassium hydroxide in 75% ethanol) may be avoided in some cases by boiling phthalimide with the halide in the presence of anhydrous potassium carbonate. The cleavage of the JV-substituted phthalimide is best effected by reaction with hydrazine hydrate and then heating the reaction mixture with hydrochloric acid. The insoluble phthalylhydrazide is filtered off, leaving the amine hydrochloride in solution from which the amine may be liberated and isolated in the appropriate manner. 

You can best prepare a primary amine from its alkylazide by reduction or by the Gabriel synthesis. 

Gabriel synthesis, which is most often considered as a classical approach to primary amines, can be generalized as monoalkylation of a suitably protected ammonia derivative with subsequent removal of the phthaloyl group from nitrogen. Despite its wide applicability this procedure suffers, however, from several drawbacks ... 

Aminooxindols (11/153) are rearranged to 3-cinnolinols 11/154, if treated with equimolar amounts of /-butyl hypochlorite [106] [107] [108]. Compound 11/153 is known as Neber s lactam , and is formed from 11/154 with zinc and sulfuric acid. The mechanism preferred for the 11/153 —> 11/154 transformation involves nitrene formation [106]. - As already mentioned, the Gabriel synthesis (11/155 11/157) is a method for synthesis of primary amines. But the side product is the ring enlarged hydrazide, compare Chapter IV... 

Further transamidation reactions are depicted in Scheme VI/6. In some respects, even the Gabriel synthesis, [15] [16] [17]3), a method for preparation of primary amines from N-substituted phthalimides by treatment with hydrazine,... 

Heterocyclic-2-propyne-l-amine derivatives have been prepared from propargylamine using the Gabriel synthesis (2,3) as illustrated in Eq. 2 ... 

The Gabriel synthesis consists of two steps and uses a nucleophile derived from phthalimide to synthesize 1° amines via nucleophilic substitution. The Gabriel synthesis begins with... 

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