N, O-dimethylhydroxylamine hydrochloride

Horner-Emmons reaction of N-terminal blocked aldehyde 1 with sulfonylphosphonates in the presence of sodium hydride gives the amino acid vinyl sulfone 2, which is deprotected with acid and converted into its chloride or tosylate salt 3 and coupled by the mixed anhydride method with an N-terminal protected peptide or amino acid to give the desired peptide vinyl sulfones 4 (Scheme 2). 4 5 N-Terminal protected aldehydes 1 are obtained from reduction of Boc amino acid V-methoxy-A-methylamides (Weinreb amides, see Section 15.1.1) by lithium aluminum hydride. 9 The V-methoxy-V-methylamide derivatives are prepared by reaction of Boc amino acids with N,O-dimethylhydroxylamine hydrochloride in... 

ALDEHYDES Acetone cyanohydrin. Dichlorobis(cyclopentadienyl)titanium(II). Diisobutylaluminum hydride. Dimethylformamide. N,0-Dimclhylhydroxylamine hydrochloride. 4-Eormyl-l -methylpyridinium hcnzcncsuifonatc. N-Formylpiperidine. N.O-Dimethylhydroxylamine hydrochloride. 2-(2,6-l)imethylpipcridino)aectonitrile Mclhoxy(triniclhyl.silyl)incihyl lidiiiim... 

KETONES N.O-Dimethylhydroxylamine hydrochloride. N,N,-Diphenyl-/>-mcthoxyphenylchloromethyleniminum chloride. Formaldehyde dimethyl dithioacetal S.S-dioxidc 4-Fonmyl l methylpyridiniuni bcnzencsullonatc. l.ithi[Pg.651]

Boa-L-Leuoine N-msthyl-O-methyloarboxamide. A 1-L, three-necked, round-bottomed flask is equipped with a mechanical stirrer, an electronic digital thermometer, and a graduated addition funnel. The flask is charged with 39.1 g (0.4 mol) of N,0-dimethylhydroxylamine hydrochloride (Note 1) and 236 mL of methylene chloride (Note 2). The suspension is stirred and cooled to 2°C with an ice-water bath. N-Methylpiperidine (Note 3), 48.8 ni. (0.41 mol), is placed in the addition funnel and added dropwise while the temperature is maintained at 2° + 2°C. A clear, colorless solution results which is kept cold and used in the following reaction. 

We studied this reaction by calorimetry and found that the addition of triisobutylaluminum to a suspension of N, O-dimethyl-hydroxylamine hydrochloride in THF was highly exothermic. It was also noted that the resulting complex of triisobutylaluminum/A, O-dimethylhydroxylamine /THF was thermally unstable. According to differential scanning calorimetry, this complex started to exothermically decompose at 30 °C and reached the maximum exotherm at 140 °C, resulting in the release of a total of -406 kJ/kg of heat. This instability is presumably due to an aluminum-catalyzed polymerization reaction of tetrahydrofuran. Thus,... 

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