Enantioselective Synthesis of 2-Substituted 5-, 6- and 7-Membered Lactams via α-Alkylation of Their Chiral N-Dialkylamino Derivatives
作者:Dieter Enders、Robert Gröbner、Gerhard Raabe、Jan Runsink
DOI:10.1055/s-1996-4443
日期:1996.8
2-Alkyl-substituted lactams 4 were synthesized in good overall yields and high enantiomeric purities (ee =71-99%) by α-alkylation of chiral N-(dialkylamino)lactams 2 and subsequent reductive N-N bond cleavage of the resulting lactams 3 with lithium in liquid ammonia. The lactams 2, in turn, were prepared in good yields by cyclization of Ï-chloroalkanohydrazides 1 with sodium hydride. Acidic hydrolysis of lactams 4 leads to γ-aminobutanoic acid (GABA) derivatives 5 (ee ≥ 99%). The absolute configuration was determined by polarimetry and an X-ray structure analysis of (S,S)-3e’.
通过手性N-(二烷基氨基)内酰胺2的α-烷基化反应,随后在液氨中使用锂进行所得内酰胺3的还原性N-N键断裂,合成了具有良好总收率和高对映体纯度(ee = 71-99%)的2-烷基取代内酰胺4。这些内酰胺2是通过将β-氯代烷基酰肼1与氢化钠环合反应制备的,收率良好。内酰胺4的酸性水解得到γ-氨基丁酸(GABA)衍生物5(ee ≥ 99%)。绝对构型通过旋光仪测定和(S,S)-3e’的X射线结构分析确定。