Synthesis of Enantiopure 5-Substituted 2,3-Methanopyrrolidines by Cyclization of Enantiopure α-Branched α-N-Homoallylamino Nitriles
摘要:
The preparation of 5-substituted 2,3-methanopyrrolidines by the stereoselective cyclization of zincated alpha-amino nitriles derived from enantiopure alpha-branched homoallylamines has been investigated. The formation of trans adducts in excellent diastereoselectivities (up to > 98:2) and good yields (up to 71%) is observed. The absolute configuration and enantiomeric excess are dependent on the nitrogen protecting group.
Stereoselective cyclization of zincatedα‐N‐homoallylaminonitriles has been developed. Following treatment with lithium diisopropylamide (LDA) and transmetalation with zinc bromide, α‐N‐(1‐phenylethyl)‐N‐homoallylaminonitriles lead to 2,3‐methanopyrrolidines in moderate to good yields (up to 66 %) and excellent selectivities (up to >98:2). With substrates derived from α‐branched homoallylic amines
The preparation of 5-substituted 2,3-methanopyrrolidines by the stereoselective cyclization of zincated alpha-amino nitriles derived from enantiopure alpha-branched homoallylamines has been investigated. The formation of trans adducts in excellent diastereoselectivities (up to > 98:2) and good yields (up to 71%) is observed. The absolute configuration and enantiomeric excess are dependent on the nitrogen protecting group.