Oximes preparation

Nifuroxime. The anti form of the oxime prepared from 5-nitro-2-furancarboxaldehyde and hydroxylarnine, has been marketed for topical use as an antibacterial or an antifungal agent (1,17). 

Meldmm s acid 5-oxime, prepared by reaction of Meldrum s acid and NO followed by tautomerism of the nitroso group, thermolyzes at elevated temperatures analogously to give the highly reactive nitrosoketene <1997H(46)503, 1998H(47)383>, which has been characterized spectroscopically (Equation 15) <2002JRS443>. 

SYNTHESIS To a well stirred solution of 14.8 g hydroxylamine hydrochloride in 120 mL MeOH there was added 3.6 g of 3,4-methylenedioxyphenylacetone (see under MDMA for its preparation) followed by 1.0 g sodium cyanoborohydride. The oxime, prepared from the ketone and hydroxylamine in MeOH with pyridine, may... 

Picha et al. (2005) returned to monopyridinium compounds (35) with a hydroxyiminomethyl group modified in the side-chain, with the aim of improving the nucleophilicity of this group (Figure 66.28). From the eight oximes prepared and tested, none achieved better reactivation potency if compared with pralidoxime, obidoxime, or HI-6 (Picha et al., 2005 Jun et al, 2008). 

FIGURE 66.35. Structures of oximes prepared in Korea and India. 

DeGrado, W. F. and Kaiser, E. T. (1982) Sohd phase synthesis of protected peptides on a polymer bound oxime preparation of segments comprising the sequence of a cytotoxic 26-peptide analog. J. Org. Chem. 47, 3258-3261. 

Dilithiated 1-tetralone oxime, prepared by treatment of 372 with an excess of LDA, was condensed with a variety of esters, affording, by acid cyclization, substituted 4,5-dihydronaphth[l,2-r ]isoxazoles 373 (Scheme 90) <2000SC3391>. 

Table 3 shows the approximate shelf-lives of oxime preparations as anticipated for ready-to-use formulations. It is obvious that aqueous solutions of trimedoxime dichloride and obidoxime dichloride and, with certain reservations, 2-PAM chloride, are sufficiently stable and therefore suitable to be used in autoinjectors. From practical and economical considerations it is of minor importance if 10% of active material is lost during storage, provided that no toxic decomposition products arise. 2-PAM solutions subjected to higher temperatures and showing considerable decomposition were less toxic to mice than freshly prepared solutions (Kondritzer etal, 1961 Barkman et al, 1963). In fact, the most toxic product expected, cyanide, was present at less than 0.05%. 

O-Vinyl oximes prepared from oximes and activated alkynes rearrange with gold catalysis to substituted pyrroles (Scheme 126). °... 

Oximes prepared from aldehydes or ketones by reaction with hydroxylamine can be reduced to primary amines in high yields. One can use various reagents for the reduction step, including Ni-H2 in methanol or L1A1H4 in ether. Using a reduction reaction, carry out the following transformations ... 

Oximes prepared from unsymmetrical ketones are likely to exist as mixtures of geometrical isomers. For example. 

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