A>Acylamination

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. 

Similarly, imides can be synthesized through the photooxidation of lactams and A-acylamines in aqueous solutions in the presence of oxygen [138] ... 

A vast majority of the amino derivatives used as substrates in the synthesis of carbohydrate aziridines are A-substituted, mostly as A-acylamines or A-aryl(alk-yljsulfonylamines. Reaction of free amines has rarely been reportedin the carbohydrate field and difficult and incomplete cyclization was generally encountered. Paulsen and Stoye, however, reported spontaneous cyclization of 6-hydrazino-5-C-mesyl-D-hexofuranoses, obtained from 5,6-di-C-mesyl-hexofura-noses by treatment with hydrazine, into the A-amino-5,6-epimino derivatives." ... 

Amido... s. a. Acylamines, Carboxylic acid amides a-Amldoa latioii s. C-a-Acyl-aminoalkylation Amidoximes... 

Treatment of an a-acylaminal derivative 83 with allylsilanes in the presence of a Lewis acid or a Brpnsted acid gives the corresponding condensation products (equation The reaction can also proceed intramolecularly, e.g. in the formation... 

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). 

Smooth acylaminations are also given by isocyanate adducts of 3-phenyloxaziridine. Ammonia and primary as well as secondary amines form the corresponding semicarbazides, e.g. (102). Owing to the fast amination reaction, shortlived substances like triazanes become accessible, e.g. the cyclohexyl compound (103), which is stable for only a few minutes at room temperature. 

Trimethylsilylketene reacts smoothly with u./V-diarylnitrones to give oxoin-doles in good yields. On the other hand, the reaction of trimethylsilylketene with N-arylmethylnitrones gives a mixture of N,N-diacylamines and N-acylamines (Scheme 2.315) (836). 

A related approach consists in the generation of endocyclic iminium ions from fV-acylaminals 209. As in the previous case, their treatment with boron trifluoride induces a diastereoselective cyclization, and thiazolo[3,4- ]pyridines 210 are isolated in good yields (Scheme 59) <2001EJ01267>. Alkenes can also participate and react well with the intermediate... 

The reactions of tetra-O-acylgluco- and -galactopyranosylaminomethy-lenemalonates (1444) and bromine in a mixture of chloroform and water at room temperature for 2 days gave the corresponding tetra-O-acylamine hydrobromides (1445) in 81-96% yields (86MI8). 

In studying the reactions betw nitroso-acylamines and diazo esters several expl compds were prepd. Some reactions involved explosion hazards) 4) F. Bucci, AnnChim (Rome), 41, 587-93(1951) CA 47, 3443 (1953) (Reactions of alkali nitrites with some otg amines, such as urea may result in explns) 5) G. Armistead, ChemEngt-Progress 48, 5-10(1952) CA 46, 2298 (1952) (A review of expln hazards)... 

It has been known for a long time 82> that N-nitroso-acylamines rearrange to azo compounds ... 

The /V-acylaminals 136 can serve as substrates for the formation of fused azepinone derivatives on treatment with a catalytic amount of TiCh, although the reaction is sensitive to the nature of the R group. Thus, 138 was obtained from 136 (R = CH2OAc), but with R = Me in 136, the 6,6-fused system 137 resulted (Scheme 18) <1999TL7939>. 

---