Quaternary salts of 2-[(hydroxyimino)methyl]imidazole. 3. Synthesis and evaluation of (alkenyloxy)-, (alkynyloxy)-, and (aralykyloxy)methyl quaternarized 2-[(hydroxyimino)methyl]-1-alkylimidazolium halides as reactivators and therapy for soman intoxication
摘要:
A series of structurally related monosubstituted 1-[(alkenyloxy)methyl]-, 1-[(alkynyloxy)methyl]-, and 1-[(aralkyloxy)methyl]-2-[(hydroxyimino)methyl]-3-methyli midazolium halides were prepared and evaluated. All new compounds were characterized with respect to (hydroxyimino)methyl acid dissociation constant, nucleophilicity, and octanol-buffer partition coefficient. The alkynyloxy-substituted compounds were also evaluated in vitro with respect to reversible inhibition of human erythrocyte (RBC) acetylcholinesterase (AChE) and kinetics of reactivation of human AChE inhibited by ethyl p-nitrophenyl methylphosphonate (EPMP). In vivo evaluation in mice revealed that coadministration of alkynyloxy-substituted imidazolium compounds with atropine sulfate provided significant protection against a 2 x LD50 challenge of GD. For the alkynyloxy-substituted imidazolium drugs there is a direct relationship between in vitro and in vivo activity: the most potent in vivo compounds against GD proved to be potent in vitro reactivators against EPMP-inhibited human AChE. These results differ from the observations made on the sterically hindered imidazolium compounds (see previous article) and suggest that several antidotal mechanisms of protective action may be applicable for the imidazolium aldoxime family of therapeutics. The ability of the alkynyloxy substituents to provide life-saving protection against GD intoxication was not transferable to the pyridinium or triazolium heteroaromatic ring systems.
Direct metalation of methoxymethyl arylmethyl ethers: A tin-free approach to the generation of α-alkoxyalkoxy-substituted aryllithiums
作者:Ugo Azzena、Luisa Pisano、Sarah Mocci
DOI:10.1016/j.jorganchem.2009.07.007
日期:2009.10
arylmethyllithiums was achieved by directmetalation of the corresponding arylmethyl methoxymethyl ethers. While the effect of substituents at the benzylic position is straightforward, substituents located on the aromatic ring promote the set up of a competition between lateral and aromatic metalation, strongly affected by the position and relative orthodirecting properties of the new substituent. The proposed methodology
High-valent [SnIV(Br8TPP)(OTf)2] as a highly efficient and reusable catalyst for selective methoxymethylation of alcohols and phenols: The effect of substituted bromines on the catalytic activity
tin(IV)octabromotetraphenylporphyrinato trifluoromethanesulfonate, [SnIV(Br8TPP)(OTf)2], was used for selective methoxymethylation of alcohols and phenols with formaldehyde dimethyl acetal (FDMA) at room temperature. Different primary, secondary and tertiary alcohols as well as phenols were converted to their corresponding methoxymethyl ethers with FMDA in the presence of an electron deficient tin(IV) porphyrin
<i>N,N,N′,N′</i>-Tetrabromobenzene-1,3-Disulfonamide and Poly(<i>N</i>-Bromo-<i>N</i>-Ethyl-Benzene-1,3-Disulfonamide) as Efficient Catalysts for the Methoxymethylation of Alcohols under Solvent-Free Conditions
作者:Ramin Ghorbani-Vaghei、Mohammad Ali Zolfigol、Mostafa Amiri、Hojat Veisi
DOI:10.1002/jccs.200800092
日期:2008.6
Methoxymethylation of a variety of alcohols was performed using formaldehyde dimethyl acetal in the presence of N,N,N',Ν'-tetrabromobenzene-1,3-disulfonamide [TBBDA] and poly(N-bromo-N-ethyl-benzene-l,3-disulfonamide) [PBBS] as catalysts at room temperature and solvent-free conditions. The methoxymethyl ethers (MOM-ethers) were obtained with good to excellent yields.
It was possible to functionalize the three fluorobenzyl alcohols and the three 2-(fluorophenyl)ethanols by metalation and subsequent carboxylation, the prototype electrophilic trapping reaction. Thisopropylsilyl (TIPS) outperformed methoxymethyl (MOM) as an O-protective group making seven new fluorobenzoic acids accessible in 63% average yield. Moreover, the TIPS group tolerates weakly basic and acidic media and, therefore, may facilitate further structural eldboration. The unprotected alcohols reacted more sluggishly and were unable to provide two of the targeted products (acids 1 and 2). The yield averaged only 46% in the five other cases (acids 3-7). The direct metalation of fluorinated benzyl and phenethyl alcohols remains nevertheless an attractive option because of its operational simplicity. All three (trifluoromethyl) benzyl alcohols and two of the three (trifluoromethyl)phenethyl alcohol isomers were successfully submitted to the metalation/functionalization sequence. These five starting materials gave rise to a total of nine new benzoic acids or lactones (compounds 8-14 and 17-18). Despite the poor yields (31% on average), the organometallic methods employed are, in general, extremely selective, economical and easy to perform.