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Asymmetric synthesis of norbornene based 1,4-amino alcohol derivatives and applications in asymmetric transformations

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2005
Sünbül, Murat
The asymmetric synthesis of cis-1,4-aminoalcohols with norbornene backbone was performed starting with simple and cheap anhydride 30. Quinine-mediated desymmetrization of anhydride 30 with methanol resulted in (2S,3R)-(-)-cis-hemiester 31 (98% e.e.). Chemoselective amination with HMPTA and NH4OH followed by LAH reduction afforded (2S,3R)-(+)-36 and (2S,3R)-(-)-37, respectively. The amidoester (2S,3R)-(-)-32 was transformed into chiral ligand (2S,3R)-(-)-35 with Grignard reaction followed by LAH reduction. The chiral ligands (2S,3R)-(-)-35, (2S,3R)-(+)-36 and (2S,3R)-(-)-37 were subjected to asymmetric diethylzinc addition reaction to examine their effectiveness as chiral catalyst. Among these, chiral ligand 36 exhibited the highest enantioselectivity (88% e.e.)