A convenient preparation of 2-substituted (S)-aziridines
摘要:
2-Monosubstituted (S)-aziridines (S)-3 were obtained by hydrogenation of (R)-2-sulfonyloxynitriles (R)-2 with LiAlH4 in good chemical yields and high enantiomeric excess.
A convenient preparation of 2-substituted (S)-aziridines
摘要:
2-Monosubstituted (S)-aziridines (S)-3 were obtained by hydrogenation of (R)-2-sulfonyloxynitriles (R)-2 with LiAlH4 in good chemical yields and high enantiomeric excess.
Stereoselective substitution of (R)-2-(sulfonyloxy)nitriles with sulfur nucleophiles
作者:Franz Effenberger、Sebastian Gaupp
DOI:10.1016/s0957-4166(99)00154-8
日期:1999.5
Optically active 2-(4-toluenesulfonyloxy)- and (4-nitrobenzenesulfonyloxy)nitriles (R)-3 and (R)-4, which were obtained from (R)-cyanohydrins (R)-2 by sulfonylation, react with sulfur nucleophiles such as potassium thioacetate, potassium ethylxanthogenate, potassium thiocyanate, as well as thioalcohols and thiophenol in a typical S(N)2 manner to give the (S)-2-sulfanyl nitriles (S)-7-9 and (S)-11-13 in good chemical yields and enantiomeric excesses. Even (R)-2-methyl-2-(methanesulfonyloxy)hexanenitrile (R)-6, derived from ketone cyanohydrin (R)-5, reacts with potassium thioacetate to yield (S)-2-acetylthio-2-methylhexanenitrile (S)-10 with 97% ee. (C) 1999 Elsevier Science Ltd. All rights reserved.
A convenient synthesis of (S)-2-Azidonitriles, (S)-2-aminonitriles and (S)-1,2-diamines
作者:F. Effenberger、Andreas Kremser、Uwe Stelzer
DOI:10.1016/0957-4166(96)00044-4
日期:1996.2
(S)-2-Azidonitriles (S)-4 are easily accessible from (R)-2-(sulfonyloxy)nitriles (R)-2 by nucleophilic substitution with alkali azides 3 under complete inversion of configuration. The azidonitriles (S)-4 can be converted by catalytic hydrogenation into (S)-2-aminonitriles (S)-8 and by hydrogenation using LiAlH4 into (S)-1, 2-diaminoalkanes (S)-9, respectively, both, (S)-8 and (S)-9, isolated as hydrochlorides. Hydrolysis of the aminonitrile hydrochlorides (S)-8 HCl in a saturated solution of HC1 in alcohol gives (S)-2-amino carboxamide hydrochlorides(S)-10 . HCl with enantiomeric excesses >99% after recrystallization.
Preparation of (S)-fluoronitriles
作者:Uwe Stelzer、Franz Effenberger
DOI:10.1016/s0957-4166(00)82327-7
日期:1993.2
(S)-2-fluoronitriles (S)-4 are obtained in good chemical and high optical yields from (R)-cyanohydrins (R)-2 or (R)-cyanohydrin trimethylsilylethers (R)-3 by fluorination with DAST or by nucleophilic substitution of alpha-sulfonyloxynitriles (R)-6, 7 with fluoride on polymeric supports (Amberlyst A-26 F-) under inversion of configuration of the starting cyanohydrins.