Syntheses of (−)-Funebrine and (−)-Funebral, Using Sequential Transesterification and Intramolecular Cycloaddition of a Chiral Nitrone
journal contributionposted on 05.03.2004, 00:00 by Osamu Tamura, Nobutaka Iyama, Hiroyuki Ishibashi
The first syntheses of (−)-funebrine [(−)-1] and (−)-funebral [(−)-2] are described. The syntheses feature sequential formation of nitrone VI from methyl glyoxylate (5) with oxime 6, transesterification of nitrone VI with (E)-crotyl alcohol (4), and intramolecular cycloaddition of the resulting nitrone VII bearing crotyl ester to afford cycloadduct 7 as a major product. The adduct 7 was readily elaborated to amino lactone (−)-3, the key synthetic intermediate of (−)-1 and (−)-2.