Stereoselective Formal Synthesis of (±)-Monomorine I from 6-Methyl-2-piperidinone
1990; Elsevier BV; Volume: 30; Issue: 1 Linguagem: Inglês
10.3987/com-89-s57
ISSN1881-0942
AutoresTatsuo Nagasaka, Hiroki Kato, Hideki Hayashi, Masako Shioda, Hiromi Hikasa, Fumiko Hamagichi,
Tópico(s)Asymmetric Synthesis and Catalysis
ResumoThe stereoselective formal synthesis of (+)-monomorine I from 6-methyl-2-piperidinone was achieved.A general method for the synthesis of w-alkylated lactams is also described.The N-alkoxycarbonylation of a lactam was found to activate the carbonyl group of the lactam to make it more reactive to nucleophiles such as hydridesl and carbanions.*Some antibiotic^,^ alkaloidsr4 and metabolites5 have been synthesized by this means.In the present study, the stereoselective formal synthesis of (?Imonomorine I (=) from 6-methyl-2-piperidinone (1) is described.(+)-Monomorine I is an alkaloid isolated from the cosmopolitan ant, Manomorium pharaonis (L.).6Although it was possible to obtain 6-methyl-2-piperidinone (1) by the Schmidt reaction of 2-methylpentanone7 or the Grignard reaction of qlutarimide followed by reduction with sodium cyanoborohydride,' these methods are not convenient and their yields are not reproducible.'Thus, a general method for the preparation of w-methyllactams was devised and is shown in Scheme 1. Reductive cyclization ( H 2 150 atm, Raney Ni, 150nC, 7 h) of oxirnes (2-4)9 gave w-methyllactams (6-5) in Scheme 1 N-OH H 2 , 150 atm COOR Raney N i EtOH 150°, 7 h x 8, NH), 2.30-2.80(2H.m, NCH x 2).3.92 l4H, m, 0CH2CH20).1 3 ~-~m r ICDCl3) 6
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