Oxidation acylamination

The N-oxides of isoquinolines have proved to be excellent intermediates for the preparation of many compounds. Trialkylboranes give 1-alkyl derivatives (147). With cyanogen bromide in ethanol, ethyl N-(l- and 4-isoquinolyl)carbamates are formed (148). A compHcated but potentially important reaction is the formation of 1-acetonyLisoquinoline and 1-cyanoisoquinoline [1198-30-7] when isoquinoline N-oxide reacts with metbacrylonitrile in the presence of hydroquinone (149). Isoquinoline N-oxide undergoes direct acylamination with /V-benzoylanilinoisoquinoline salts to form 1-/V-benzoylanilinoisoquinoline [53112-20-4] in 55% yield (150). A similar reaction of AJ-sulfinyl- -toluenesulfonamide leads to l-(tos5larriino)isoquinoline [25770-51-8] which is readily hydrolyzed to 1-aminoisoquinoline (151). 

The next step in the development of periodate oxidation was made by Nicolet and Shinn.8 They applied periodate oxidation to a series of a-amino acids, and found that those containing the 2-hydroxyamine structure are almost instantaneously oxidized. For such an oxidation to proceed rapidly, the amine could not be tertiary. An a-hydroxy A-acylamine was attacked very slowly, if at all. Only a small number of compounds were investigated. 

The photocyclization of 3-nitro-2-pyridyl-DL-leucine (354) to 2-isobutyl-imidazo[4,5-i]pyridine (355) has been studied spectrophotometrically and the quantum yield of the reaction determined as a function of pH (72JCS(P2)2218). 3-iV-Methanesul-fonamidopyridine 1-oxide (356) is acylaminated at C-2 by phenylbenzimidoyl chloride (357) and the intermediate 2-acylaminated product (358) cyclized to 2,3-diphenyl-imidazo[4,5-i]pyridine (359) (74JOC1802). 

Pyridazine 1-oxide is acylaminated with N-phenylbenzonitrilium hexa-chloroantimonate to give 3-N-benzoyIanilinopyridazine [Eq. (21)]. A new... 

Case Study 6.39 Photocatalysis - oxidation of lactams and /V-acylamines... 

Phosphoryl chloride and triethylamine appears to be the reagent combination of choice for the conversion of 2-methylpyridine 1-oxide into 2-chloromethylpyridine. The mechanism of the acylamination and amino-arylation of the side-chain of 2- and 4-methylpyridine 1-oxides (Scheme 24)... 

Conversion of an amine into a substituted amide is a convenient and widely used method for the protection of amino groups. Monoacylation of a primary amine often affords sufficient protection, i.e., against oxidation, alkylation, etc., and more complete protection is obtained by forming cyclic diacyl derivatives. Acyclic diacylamines easily revert to mono-acylamines and have only been used under very mild conditions [20]. Of the simple acylamines in common use the stability increases in the order formyl < acetyl < benzoyl and many more complex acyl groups have been evaluated in order to adjust the stability of the derivatives for various purposes. 

Through Oxidative Carbon-Carbon Bond Cleavage 184 5.2. Fragment Coupling Through N-Acylaminal Formation and ... 

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