Cyclizations of substituted benzylidene-3-alkenylamines: synthesis of the tricyclic core of the martinellines.
The martinellines (1 and 2) are natural products that possess both interesting biological activity and chemical structure. During the investigation of a hetero Diels-Alder route to these molecules, alternate Lewis acid-dependent cyclizations of (2'-amino-N'-tert-butoxycarbonyl-5'-chlorobenzylidene)-3-butenylamine (10) were observed. The reaction of a variety of imines with TMSOTf or TiCl(4) led to the formation of different heterocycles including iminodibenzo[b,f][1,5]diazocines, hexahydropyrido[1, 2-c]quinazolin-6-ones, tetrahydropyrrolo[1,2-c]quinazolin-5-ones, 2-arylpiperidines, and 2-arylpyrrolidines. Tetrahydropyrrolo[1, 2-c]quinazolin-5-one 54, obtained via this new methodology, was used as an intermediate in the synthesis of the tricyclic ring system (65) of the martinellines.
Frank
K E
KE
Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66045-2506, USA.
Aubé
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D000588:Amines / Q000737:chemistry*; D001597:Benzylidene Compounds / Q000737:chemistry*; D015394:Molecular Structure; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry; D011804:Quinolines / Q000138:chemical synthesis* / Q000737:chemistry; D013057:Spectrum Analysis
D000588:Amines; D001597:Benzylidene Compounds; D011758:Pyrroles; D011804:Quinolines; C410408:martinelline