| Title
| - Benzolactams. 4. Reaction of 3‘,4‘- or 4‘,5‘-Dialkoxy-Substituted1-(2‘-Bromobenzyl)-2-ethoxycarbonyl-1,2,3,4-tetrahydroisoquinolineswith Alkyllithium. 1,2 and 1,4 Additions of Alkyllithium toBenzolactams
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| Abstract
| - Treatment of 1-(2‘-bromo-3‘,4‘-dialkoxybenzyl)-1,2,3,4-tetrahydroisoquinoline carbamates, 1a,c, withexcess alkyllithium gave 8-oxoberbines, 2a,c, which were successively attacked in situ with anothermolecule of alkyllithium to give 1,2 and/or 1,4 addition products. A primary alkyllithium, such asMeLi or BuLi, gave a 1,2 addition product, 8-methyleneberbine 9a or 8-butylideneberbine 3a. t-BuLipreferred 1,4 addition, followed by elimination of the alkoxy group, to give 9-tert-butyl-8-oxoberbine6a or 7c. s-BuLi gave a mixture of 1,2 and 1,4 addition products, 1-[2‘-(2‘ ‘-methylbutyryl)benzyl]-1,2,3,4-tetrahydroisoquinoline 4a and 9-s-butyl-8-oxoberbine 5a. Similar treatments of carbamate1b having no alkoxy group at its 3‘ position gave 1,2 addition products, 8-butylideneberbine 3b,1-[2‘-(2‘ ‘-methylbutyryl)benzyl]-1,2,3,4-tetrahydroisoquinoline 4b, and 1-(2‘-pivaloylbenzyl)-1,2,3,4-tetrahydroisoquinoline 6b, in all cases. Reactions of 1a with s-BuMgCl and isoPrMgCl also gavethe 1,4 adduct, 5a, and its 9-isoPr analogue, 12a. Treatment of 9a with excess NaBH4 in AcOHgave (±)-coralydine (10b).
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