Syntheses of (-)-funebrine and (-)-funebral, using sequential transesterification and intramolecular cycloaddition of a chiral nitrone.
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.
Tamura
Osamu
O
Faculty of Pharmaceutical Sciences, Kanazawa University, Takara-machi, Kanazawa 920-0934, Japan. tamura@p.kanazawa-u.ac.jp
Iyama
Nobutaka
N
Ishibashi
Hiroyuki
H
D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D035161:Bombacaceae / Q000737:chemistry; D002236:Carbohydrate Conformation; D003500:Cyclization; D004951:Esterification; D007783:Lactones / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009589:Nitrogen Oxides / Q000737:chemistry*; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D013237:Stereoisomerism
D000470:Alkaloids; D007783:Lactones; D009589:Nitrogen Oxides; D011758:Pyrroles; C484609:funebrine; C015388:nitrones; C050250:funebral