The aza-Michael addition of (S)-1-amino-2-methoxymethyl-pyrrolidine (SAMP) to alkenyl sulfones (E)-1, followed by reductive N-N bond cleavage with BH3×THF and N-benzylation yields N-benzyl-protected β-amino sulfones (R)-3 with high enantiomeric excesses (ee ≥ 96%). Subsequent α-alkylation of (R)-3 with various electrophiles leads to α-alkyl-β-amino sulfones (R,R)-4a-e in excellent yields (88-97%) and finally high diastereomeric (de = 96 - ≥ 98%) and enantiomeric purity (ee ≥ 96%). The absolute configuration was determined by X-ray structural analysis and confirmed by NMR spectroscopy (NOE-experiments).
将(S)-1-
氨基-2-甲氧甲基-
吡咯烷(
SAMP)与烯基砜(E)-1进行氮-氮键的加合反应,然后使用
BH3×THF还原并切断N-N键,最后进行N-苄基化,得到具有高对映体过剩(ee≥96%)的N-苄基保护β-
氨基砜(R)-3。随后,将(R)-3与各种亲电体进行α-烷基化,得到α-烷基-β-
氨基砜(R,R)-4a-e,收率极高(88-97%),最后得到高立体异构体(de=96-≥98%)和对映体纯度(ee≥96%)。通过X射线结构分析确定绝对构型,并通过核磁共振光谱(NOE实验)进行确认。