Alkylation, Arylation, and Acylation

Alkylation of compound 2 has been confirmed at position 1 as predicted for methylation (dimethyl sulfate) and ethylation (triethyloxonium fluoroborate) (93T4307), and in the simple case of compound 193 (94AJC1009), and in the compound 194 (82MI1). The ylide 195 (84JCS(P1)1891) is substituted at position 3. 

Arylation of compound 5 with a 2-chloropyridine gives compound 204 (97TL8607). Alkylation of 1-substituted derivatives gives quaternary salts such as 205 (94ZOK440). 

There are many examples of alkylation using complex side chains, where the triazolopyridine is one of many heterocyclic termini in antibiotics. Mention of these will be found in Section V.B. 

The hydroxy compound 59 has been acetylated (94AJC991), and many glycosides have been protected by acetylation. The 4-thione 209 (85LA1922) and the 3-thiol 210 (83USP4419516) have been alkylated using methyl iodide with potassium hydroxide and chloroacetonitrile with triethylamine respectively. 

---

Alkylation, arylation, and acylation of nitrogen in triazole have all been extensively explored and a wide range of reagents have been used. Both the protonated and deprotonated nitrogen substrates have been used. 

Transition-metal-mediated alkylation, arylation, and acylation... 

Alkylation, arylation, and acylation, at the heteroatom, lead to substitution of an NH or to onium salts. Three-membered ring onium salts are difficult to isolate, and very weakly nucleophilic counterions must be used, such as BF4. 

As mentioned in Section I, one of the remarkable features of 1,1-enediamines is the enhanced enaminic reactivity of the / -carbon atom. 1,1-Enediamines can serve as nucleophiles in substitution of and addition reactions to a wide variety of electron-deficient reagents. In this section we discuss mainly the alkylation, arylation and acylation reactions of 1,1-enediamines, emphasizing their synthetic utilities, especially those of secondary enediamines. 

Alkyl, aryl and acyl nitrosyl phosphines and hydridophosphine complexes of Ru11 are covered in Sections 45.5.4.6.iii and 45.10 respectively. 

It appears that mass spectrometry is of considerable value in structure determination although, at present, it is not possible to differentiate between 2- and 4-substituted isomers. The technique has been used to establish the structure of 4-(imidazol-4-yl)butane-1,2,3-triol55 which, unlike most carbohydrate derivatives, shows a molecular ion. The mass spectra of 2-alkylbenzimidazoles246 and mercaptoimidazoles124 have been examined, while use has been made of mass spectrometry in the identification of some alkyl, aryl, and acyl imidazoles.138... 

I. rf Acyl Metal Complexes by Oxidative Addition. 

Oxidative addition of organic halides to low-valent metal complexes generates reactive metal alkyls that can then be used in insertion, coupling, carbonylation-decar-bonylation and cyclization reactions for organic synthesis. These transformations can be made catalytic after development of the stoichiometric chemistry using the more stable metal alkyls. This section surveys the reactions of alkyl, aryl and acyl halides with transition metal complexes of the groups IIIA (lanthanides and actinides), IVA-VIII and IB. 

Group VIII Fe, Ru, Os. Five-coordinated complexes of the iron triad metals M(0) and M(I) undergo oxidative addition with alkyl, aryl and acyl halides to give 6-... 

S.8.2.9.2. (t )-(T-Alkyl-, -Aryl-, and -Acyl-Metal Complexes by Reaction with Metal-Complex Anions. 

In their zerovalent compounds, all three metals (Ni, Pd, Pt) undergo oxidative addition of alkyl, aryl, and acyl halides. For palladium, in particular, such reactions are key steps in a wide range of catalytic reactions. Palladium(II) and platinum(II) complexes also add C—X bonds to generate Pd(IV) and Pt(IV) species. Since C—C or C—H bond formation by reductive elimination often occurs readily, a common reaction sequence involves C—X addition followed by coupling of two alkyl groups, or an alkyl and a hydride ligand. 

In order to obtain alkyl-, aryl- and acyl- guanidines Wang linker is treated with carbonylimida-zole and thiourea consecutively. The displacement of sulfur by primary or secondary amines leads to acid-labile carbamate linkage [119]. 

Purines react readily with hydroxyl, alkyl, aryl and acyl radicals, usually at C-6, or at C-8 (or C-2) if the... 

---