Bunsuke Umezawa

A synthesis of (±)-Δ2-α-Lycoren-7-one, the key intermediate for the total synthesis of (±)-lycorine

Abstract (±)-α-Lycoran-3,5-dione (14a) was prepared from octahydrophenanthridin-3-one (8b) obtained by two methods starting from 5-aryl-4-nitrocyclohexene (2) and 1-hydroxyl-2-aryl-5-oxo-cyclohexanecarboxylic acid (10), both of which were prepared by the Diels-Alder reaction of 3,4-methylenedioxy - ω - nitrostyrene with butadiene and the Robinson annelation of 3,4-methyl- enedioxy - phenylpyruvic acid (9) with methyl vinyl ketone, respectively, 14a was converted into (±)Δ2-α-lycoren-7-one (22b), which has been transformed into (±)-lycorine (1) by Torssell

Immobilized lipase catalyzed hydrolysis of labile acetate: enantioselective hydrolysis of (±)-4-acetoxy-1,2,3,4-tetrahydro-6,7-dimethoxy-2-methylisoquinoline

Abstract Enzymatic hydrolysis of the title alkaloid ( 1 ) by using lipases immobilized with celite and cyclohexane or isooctane saturated with water gave S-(+)- 2 in high optical purity.

A novel synthesis of 9-hydroxyaporphine

Abstract (±)-N-Methyllaurotetanine (3) was readily prepared via the o -quinol acetate (2), which was obtained from the 1-(3′-hydroxybenzyl)-tetrahydroisoquinoline (1) by lead tetraacetate oxidation.

A Convenient Preparation of Certain N, Ndialkylcarbamoyl Chlorides

Abstract Certain N, N-dialkylcarbamoyl chlorides (2) were prepared in moderate yields by the reaction of ethyl N, N-dialkylcarbamates (1) with phosphoryl chloride in boiling acetonitrile.

Chapter 2 Lead Tetraacetate Oxidation in Alkaloid Synthesis

Publisher Summary This chapter describes aporphines, C-homoaporphines, homoproaporphines, morphinandienones and homomorphinandienones, isopavines and homoisopavines, benzo[c]phenanthridines, 10-hydroxy-2,3,9-trimethoxydibenzopyrrocoline, tetrahydroprotoberberines, indole alkaloids, oxoaporphines, lead tetraacetate-mediated hydroxylation of isoquinoline alkaloids, and miscellaneous reaction of lead tetraacetate (LTA) oxidation in alkaloid synthesis. LTA is one of the most important oxidants in organic synthesis. Aporphine synthesis is classified in this section into four subsections A, B, C, and D, according to the location of the guiacol-type oxygenation pattern. LTA oxidation in acetic acid (AcOH) causes tetradehydrogenation, whereas in CH 2 Cl 2 the acetoxyindolenine is produced. LTA oxidation in methanol of isoreserpine gives 7-methoxy-7H-isoreserpine. The experimental result suggests the possibility that LTA oxidation followed by a similar acid treatment of (+)-1-hydroxy-2-methoxyaporphines could promote acetoxylation at C-4 and that isoquinoline alkaloids incorporating a 1,2,3,4-tetrahydro-6-methoxyisoquinolin-7-ol moiety in their skeletons could undergo the same reaction.

A fragmentation reaction of 4a-acetoxy-6-methoxy-2-methyl-7-oxo-1,2,3,4,4a,7-hexahydroisoquinoline

Treatment of the p-quinol acetate (1) with boiling MeOH in the presence of BF3·Et2O gave the 8-hydroxy-5,7-dimethoxytetrahydroisoquinoline (2). A mechanism via the phenethylammonium intermediate (10) was proposed.