A concise formal synthesis of alkaloid cryptotackiene and substituted 6H-indolo[2,3-b]quinolines.
A five-step formal synthesis of alkaloid cryptotackiene and its 2-formyl, 11-methyl/phenyl derivatives involving conjugate addition of enolate anion from cyclohexanone (or 4-methylcyclohexanone) to bis[(methylsulfanyl)methylene]-2-oxindole followed by heterocyclization in the presence of ammonium acetate as the key step has been developed. The 11-methylsulfanyl group in the initial precursor can be either desulfurized (Raney Ni) or replaced by methyl/phenyl groups via nickel-catalyzed cross-coupling reaction with appropriate Grignard reagents.
Department of Chemistry, Indian Institute of Technology, Kanpur-208016, India.
G S M
GS
Sundaram
C
C
Venkatesh
U K
UK
Syam Kumar
H
H
Ila
H
H
Junjappa
D002384:Catalysis; D031106:Cryptolepis / Q000737:chemistry; D026121:Indole Alkaloids / Q000138:chemical synthesis*; D015394:Molecular Structure; D010946:Plants, Medicinal / Q000737:chemistry; D011804:Quinolines / Q000138:chemical synthesis*
D026121:Indole Alkaloids; D011804:Quinolines; C490953:cryptotackiene