Stereoselective Synthesis of Enantipure β-Amino Alcohols via Nucleophilic β-Amino-α-hydroxyalkylation by Means of 1-Lithiated 2-[N-(Diphenylmethyleneamino)]alkyl Carbamates
作者:Christiane Boie、Dieter Hoppe
DOI:10.1055/s-1997-1155
日期:1997.2
2-[N-(Diphenylmethyleneamino)]alkyl carbamates are deprotonated by means of sec-butyllithium in the presence of TMEDA or (-)-sparteine and the diastereomeric ion pairs of α-oxycarbanions formed are substituted by several electrophiles. Deprotection proceeds smoothly to yield chain-elongated β-amino alcohols. Problems arise due to nucleophilic attack of the alkyllithium at one aryl ring of the benzophenone imines under certain reaction conditions.
Rhodium/DuanPhos‐catalyzed asymmetrichydrogenation of aliphatic α‐dehydroamino ketones has been achieved and afforded chiral α‐amino ketones in high yields and excellent enantioselectives (up to 99 % ee), which could be reduced further to chiral β‐amino alcohols by LiAlH(tBuO)3 with good yields. This protocol provides a readily accessible route for the synthesis of chiral α‐amino ketones and chiral β‐amino alcohols