Oximes amino

Chiral imidazoline nitrone (88) was synthesized by condensation of hydrochloride a-amino oxime (87) with triethyl orthoformate according to Scheme 2.33... 

Formation of heterocyclic nitrones (151) from the corresponding amino oximes (150) has been observed upon treatment with Hg(II)-ethylenediaminetetraacetic acid (EDTA) (Scheme 2.54) (308, 309). 

German researchers, who were the first to discover BENAs (464), demonstrated that BENAs (434) (both terminal and internal) readily react with secondary amines to give, after aqueous treatment, the corresponding amino oximes (457) in yields from moderate to high (Scheme 3.244). 

Intermediates A and A can be separated by two procedures complete silyla-tion of these derivatives followed by fractionation of silylated amino oximes (458) or by complete desilylation of these intermediates followed by chromatographic purification of the amino oximes (459). 

In addition to standard cyclic and acyclic enamides, the effective hydrogenation of several more unusual enamides has been reported (Fig. 24.13). A concise method for the synthesis of chiral yS-amino alcohols, amino oximes and chiral 1,2-diamines has been described by Burk et al. via the enantioselective hydroge-... 

Oximes can be also used for the imidazole ring synthesis. Thus, reaction of a-amino-oximes 122 and orthoesters leads to imidazole Af-oxides 123 (equation 53) . Interaction of a-ketooxime 124 with triazinanes also afforded imidazole Af-oxides 125 in good yields (equation 54) . Similarly, a-ketooximes in the system NH3/H20/aromatic aldehyde afforded trisubstituted 1-hydroxyimidazoles . ... 

Although they are much less common, the fragmentations can also be assisted by nitrogen or sulfur substiments at the a-carbon atom. An immonium salt has to be an intermediate in the fragmentation of a-amino oximes, which on hydrolysis produce a carbonyl group (ketone or aldehyde). 

It was observed that a-amino oximes 511, when treated with sodium borohydride in boiling acetonitrile, produced the expected fragmentation products 513 in moderate to good yields (31-87%) (equation 225). The use of the hydride-induced fragmentation in cyclic oximes leads to amino nitrile compounds, as a result of the reduction of the immonium salt intermediates 512. Careful selected oxime structures showed that the reaction time increases when the stabihty of the immonium intermediate decreases, showing the importance of the mesomeric assistance. 

Further details of the photoaddition of N-nitrosopiperidine to a-pinene have been published.The claim of a-fenchen-6-one oxime formation (Vol. 7, p. 43) has been retracted the product is optically active carvone oxime. The stereochemistry and conformations of amino-oximes derived from a-pinene nitroso-chloride have been examined. ... 

Cl2N4O2C 3H30, 3-Pentanone, 2-[[3-[[2-(hydroxy imino)-1, l -dimethyl propyl] amino]propyl]amino]-, oxime, dihydrochloride, [104484-57-3], 31 273... 

It can also be prepared from -nitrobenzyl alcohol and sodium sulfide,4 by heating -nitrobenzaldehyde with sodium bisulfite 5 and decomposing the addition product with hydrochloric acid, or in low yield by the reduction of />-nitrobenzaldoxime with ammonium sulfide 6 7 and subsequent acid hydrolysis of the amino oxime. 

Oxadiazol 3,5,5-Trimethyl-4,5-dihydro- E14a/2, 360 (aus 2-Amino-oxim)... 

Dimethyl-2-oxo-4-phenyl-2,5-dihydro- -3-oxid El4b, 1432 (Amino-oxim/COCl2)... 

The nitroso chlorides prepared from limonene, sylvestrene, 3-carene, and a-pincnc have been converted to a-amino oximes by treatment with aliphatic and aromatic amines with unspecified yields39,42,43-15°-151. The configuration of the products was determined by NMR spectroscopy, molecular mechanics calculations and X-ray crystallographic analysis 50, in some cases reversing the configuration previously assigned. The stereochemical outcome of the reaction is rationalized by attack of the amine from the least hindered side of the intermediate nitroso alkene. 

Preparation of /1-Amino Nitroso Compounds and a-Amino Oximes by Photochemical Addition of /V-Nitroso Amines... 

Protonated A-nitroso amines undergo photolytic decomposition from the excited state generating transient aminium radicals and nitric oxide. Aminium radicals, which are electrophilic radicals, initiate the addition to alkenes to give //-amino nitroso compounds or oc-amino oximes (Section 7.2.5.2), however, under an oxygen atmosphere, //-nitryloxy amines (/i-amino nitrates) are produced through peroxynitrites intermediates97-99. 

---