Oxime O-methyl

Methoxy- -oxim 379 4-Methoxy-phenyl- 631 -O-methyl-oxim 378 2-Nitro- 311 4-Nitro- 285, 765 -oxim 374, 502. 613 -phenylimin 609 -2-phenyl-propyl-(2)-imin 609 4-Phenylthio- 673 2-Thiocyanat- 635 m,ft),o)-Trifluor- 543... 

Benzyl- 112, 240, 346, 355 f., 358, 436, 611 ff., 680 aus Benzaldehyd-O-methyl-oxim und Diboran377 aus Benzonitril und Natriumboranat 115 aus O-Benzoyl-benzhydroxamsaure und Lithium-alanat 264... 

Chlor-3-aminosulfonyl- 182 4-Chlor- -benzylimin 664 4-Chlor- -4-chlor-phenylimin 362 4-Chlor- -O-methyl-oxim 375... 

Dihydroxy- -oxim 699 4,4 -Dimethoxy- -O-methyl-oxim 377 4-(2,3-Dimethyl-butyl-(2)]- 565 2,2 -Dinitro- 474, 558 4,4 -Diphenyl- 542 2 -Fluor-4-chlor- 288... 

Titanium enolates of various carbonyl compounds play an increasingly important role in Mannich-type reactions with different electrophiles. Recently, Liotta and co-workers reported a novel diastereoselective addition of chloro-titanium enolate 80 of iV-acylthiazolidinethione to various types of O-methyl oximes to afford the desired anti-azetines, precursors of a,/3-disubstituted /3-amino carbonyl derivatives 82 (Scheme 32).109... 

Fig. 56 Stereoselective intramolecular coupling of a carbonyl group with an O-methyl oxime [308].

Figure 13. Electron impact spectra (70 eV) of aldehyde o-methyl oximes...

Figure 16. Total ion current plot for the GC/MS analysis of selected aldehyde o-methyl oximes in the presence of fipyfold excess hydrocarbons. (Methoxime doublet peaks are from chromatographic resolution of syn and anti conformers.)...

In 2002, Kanno and Taylor successfully developed a simple one-pot procedure using MnOi/NHiOMe-HCl for the conversion of activated primary alcohols into O-methyl oximes (Scheme 11). They also developed a modification using Amberlyst 15-supported alkoxylamines, which can be employed to prepare other types of 0-aUcyl oximes as well as the parent hydroxylamines. This latter procedure has been used as the cornerstone of an efficient synthesis of the antifungal natural product citaldoxime 11 (Scheme 11). Citaldoxime is an antifungal natural product first obtained as a radiation-induced stress metabolite of Citrus sinensis , and later isolated from the roots of several different citrus plants. ... 

Ozonolysis of the O-methyl oximes of cyclic ketones in the presence of 1,4-cyclohex-anedione and ozonolysis of the O-methylated dioxime of 1,4-cyclohexanedione in the presence of cyclic ketones afforded the corresponding diozonides . 

By contrast, the X-ray crystal structures of both 2-formylbenzeneboronic acid (13) and its O-methyl oxime (14) reveal an intramolecular hydrogen bond in which one hydroxyl of the B(OH), unit truly acts as a hydrogen bond donor to a heteroatom of the ortho side chain <94MI621>. The hydrogen bond distance in the seven-membered ring is 1.562 A in 13 and 1.614 A in 14. 

In gleicher cheraischer Ausbeute, jedoch mit einer optischen Ausbeute von 76%, laBt sich Acetophenon-(O-methyl-oxim) mit Lithium-alanat in Gegenwart eines aus Diboran und (S)-2-Amino-3-methyl-l,l-diphenyl-butanol gebildeten Boran-Adduktes zu (S)-l-Amino-1-phenyl-ethan reduzieren2. 

Thermally induced isomerization of the benzocyclobutane (83) gives the pyrroloisoquino-line (84), the pyridine ring of which can be aromatized with iron(III) chloride (Scheme 29). Similarly, the aldehyde (85 X = 0) or its O-methyl oxime (85 X = NOMe) gives the cis-trans mixture (86). If p- toluenesulfonic acid is included in the reaction mixture the pure cis compounds are obtained (72AG(E)l03l). 

It is known that electrochemical reduction of oximes in protic media occurs in two steps the N—O bond is first reduced to form an imine and the latter is then reduced to afford a primary amine1,29. Tallec has shown that the amine from oxime 33 can be trapped intramolecularly (equation 16)35. Interestingly, the SS diastereomer predominates the chiral pyrrolidine ring derivative serves to control the stereochemistry of formation of the new benzylic chiral center. Electrochemical reductive cross-coupling of O-methyl oximes with carbonyl compounds in isopropanol at a tin cathode affords adducts (equation 17) which can be reduced further to 2-amino alcohols36. In this fashion, menthone could... 

The Griesbaum Coozonolysis allows the preparation of defined, tetrasubsituted ozonides (1,2,4-trioxolanes) by the reaction of O-methyl oximes with a carbonyl compound in the presence of ozone. In contrast to their traditional role as intermediates in oxidative alkene cleavage, 1,2,4-trioxolanes with bulky substituents are isolable and relatively stable compounds. 

Alkyn-l-one O-methyl oximes (21) undergo electrophilic cyclization with a range of reagents, E-X (e.g. I2, Br2, IC1, PhSeBr), to give substituted isoxazoles (22)87... 

Carbonyl groups attached to 1,2,4-trioxolanes lower their stability, but the corresponding O-methyl-oximes are quite stable. Table 3 presents some of their 170 NMR data. 

The formation and intramolecular dipolar cycloaddition of azomethine ylides formed by carbenoid reaction with C=N bonds has recently been studied by the authors group.84 Treatment of 2-(diazoace-tyl)benzaldehyde O-methyl oxime (176) with rhodium(II) octanoate in the presence of dimethyl acetylenedicarboxylate or N-phenylmaleimide produced cycloadducts 178 and 179, respectively. The cycloaddition was also carried out using p-quinone as the dipolarophile. The major product isolated corresponded to cycloadduct 180. The subsequent reaction of this material with excess acetic anhydride in pyridine afforded diacetate 181 in 67% overall yield from 176. The latter compound incorporates the basic dibenzofa, d -cyclohepten-5,10-imine skeleton found in MK-801,85 which is a selective ligand for brain cyclidine (PCP) receptors that has attracted considerable attention as a potent anticonvulsive and neuro-protective agent.86,87... 

The formation and intramolecular dipolar cycloaddition of azomethine ylides formed by carbenoid reaction with C-N double bonds has recently been studied by the author s group [66]. Treatment of 2-(diazoacetyl)benzaldehyde O-methyl oxime (118) with rhodium (II) octanoate in the presence of dimethyl acetylenedicarboxylate or iV-phenylmaleimide produced cycloadducts 120 and... 

Reaction of a 1,3-diketone with hydroxylamine gives an isoxazole 50 via the isolable monoxime 48 and 5-hydroxydihydroisoxazole 49 (Scheme 34). Various modifications of this procedure involving other 1,3-dielectrophiles are known the examples can be represented by the reaction of alkynyl ketone 51 with hydroxylamine hydrochloride leading to the 3-substituted isoxazole 52 (Scheme 35) <2000J(P1)2311 >, and the electrophilic cyclization of O-methyl oximes 53 allowing access to a variety of 3,5-disubstituted-4-halo- or -4-selenoisoxazoles 54 under mild reaction conditions (Scheme 36) <20050L5203>. 

With oximes and O-methylated oximes, deprotonation has been shown to occur exclusively syn to the oxygen155. Deprotonation of unsymmetrical imines occurs with at least as high, and the same sense of regioselectivity as observed with ketones, i.e. the least substituted carbon is deprotonated156. 

Ozonolysis. Ozonolysis of cyclohexanone O-methyl oxime 163 in the presence of 1,4-cyclohexanedione 164 gave a complex reaction mixture containing hydroxylamines 164, as a main product (Scheme 71 <1997T5463>). 

Reaction of cyclohexanone O-methyl oxime 163 with chloroacetone gave a similar spectrum of products with a similar ratio and yield (Scheme 72 <1997LA1381>). 

O-tnethyl oxime and 252A a hydroxy O-methyl oxime, as shown in Fig. 19. The configuration of the 0-methyloxime is not rigorously established, but it appears to be as shown for 236 and 252A (/5i). Reduction of 236 with sodium in butanol afforded a primary amine, consonant with the oxime structure of 236 (/5i). Reduction of synthetic nitropolyzonamine (see below) yields the same primary amine (K. Hutchinson, H. M. Gar-raffo, T. F. Spande, and J. W. Daly, unpublished). 

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