Aminoacetaldehyde dimethylacetal

Nucleophilic displacement of 2-chloro-3-phenylquinoxaline with methylamine at 100°-150° and with sodium phenoxide in excess of phenol of 100° gives the expected 2-methylamino- and 2-phenoxy-3-phenylquinoxalines.155 2-Chloroquinoxaline and its 3-phenyl derivative undergo ring closure with aminoacetaldehyde dimethylacetal to an imidazo[l,2-a]quinoxaline.136 Nucleophilic substitution of 2-chloro-quinoxaline with hydroxide ion in water is accelerated by cationic micelles and retarded by anionic micelles. These results were correlated with reactions of l-chloro-2,4-dinitrobenzene, and the characteristics of their transition states were discussed.137... 

Methyl /3-hydroxypropionimidates (12) (prepared from ethylene cyanohydrin, methanol, and HO) condense with aminoacetaldehyde dimethylacetal (13) to yield an amidine hydrochloride (14) which undergoes ring closure to an imidazole.87 Applications of this reaction have been used in the synthesis of 2-phenylimidazole and its 4-alkyl derivatives,88 some new 2-mercaptoimidazoles,89 and isohistamine .90 Isohistamine [2-(2 -aminoethyl)imidazole], originally reported in error by Jones,01 was prepared in 50% yield by an adaptation of the method of Ellinger and Goldberg92 and proved by NMR spectroscopy to be the authentic compound. The compound prepared... 

The aromatic ring system has been prepared both from quinoxaline intermediates and from 1-phenylimidazoles. Reaction of the 2-chloroquinoxalines 1 with aminoacetaldehyde dimethylacetal followed by acid treatment of the resultant aminoacetals gave imidazo[l,2-ajquinoxaline (2) and its 4-phenyl derivative (3). Compound 3 was the... 

Studies of cobaloximes as models for coenzyme Bjg continue to appear. In a recent paper a D mechanism was confirmed for the ligation of rra/w-[Co(dmgH)a-R(0H2>] (R=range of alkyl groups) by aminoacetaldehyde dimethylacetal (DEA, NH2CH2(OMe>2]. A summary of the variation in the rates of formation and dissociation of DEA complexes with changes in R is given in Table 9. The complex... 

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