Amines, acylated oxidation

POLONOVSKI REACTION. Demethylation of tertiary (or Heterocyclic) amine A-oxides on treatment with acetyl chloride or acetic anhydride 1o give A-acylated secondary amines and formaldehyde, along with (9-acylated aminophenols as a result of a side reaction. 

The electrochemical oxidation of acyl silanes has been investigated, giving rise to esters and amides when carried out in the presence of alcohols and amines. The oxidation potentials of acyl silanes proved to be much lower than those of the corresponding ketones213. 

Aminopenici11 anic acid (I) is acylated, oxidized and esterified to give the sulfoxide ester (II). Sulfoxide ester (II) is converted to its C-6 epimer (III) by treatment with trimethyl chiorosilane and triethyl amine. Rearrangement of III using triphenyl phosphine yields the epioxazoline (IV). 

The azocane nitrogen undergoes reactions characteristic for secondary amines nucleophilic substitutions (alkylations and acylations), oxidations, and modifications to ring substituents. Alkylations. Halo derivatives were reported to react readily with azocanes to afford in good yields compounds with diverse applications in life sciences (Scheme 101 <1997JME1578 . 

Dethiation Alkylation and acylation Halogenation Amination Hydrolysis Oxidation... 

The first step in the Polonovski reaction of an amine N-oxide with an acid anhydride, acyl chloride or chloroformate ester is the formation of the 0-acylimonium salt (1 Scheme 1). Such species are highly unstable. However, they can be detected in situ ( H NMR), and in certain cases actually isolated, if prepared using powerful acylating agents such as acetyl perchlorate. 

REACTIONS OF ENOLATES WITH OTHER ELECTROPHILES HALOGENATIONS, AMINATIONS, ACYLATIONS AND OXIDATIONS... 

The reaction of pyridazin-3-amine 1-oxide with diethyl (ethoxymethylene)malonatc gives A-[bis(eLhoxycarbonyl)methylene]pyridazin-3-amine 1-oxide (1), the starting compound for a thermal cyclization to give ethyl 5-oxo-5,8-dihydropyrido[2,3-r]pyridazine-6-carboxylate 2-oxide (2).27 By analogy to the second step of the Gould-Jacobs reaction,28 the acylation step is facilitated by the A-oxide function. 

Examples for the alkaline hydrolysis of acylated 2-amino groups are the formation of 6-bromo-l-methylpyrido[2,3-i/]pyrimidine-2,4(l//,3//)-dione (35) from 6-bromo-l-methyl-2-(pivaloylamino)pyrido[2,3-[Pg.151]

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