Liebigs Annalen der Chemie

Nucleophilic Acylation of 3, 4??Dihydroisoquinolinium Salts. Diastereoselective Synthesis of the Protoberberine Alkaloid (±)??Corydaline and of Analogous Compounds

LF Tietze, G Brill

Index: Tietze, Lutz F.; Brill, Gunter Liebigs Annalen der Chemie, 1987 , p. 311 - 319

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Abstract

Abstract Nucleophilic acylation of 3, 4-dihydroisoquinolinium salts 3 with lithiated enol ethers 6, 7, and 8 or vinyl sulfides 14 leads to the adducts 4, 9, and 16, respectively, in mostly excellent yields. Hydrolysis of 4 affords 94–97% of the ketones 5, which are transformed by treatment with conc. hydrochloric acid and successive reduction with NaH 3 BCN via the enamines 18 into the dibenzoquinolizidines 19; thus 5b gives (±)-corydaline ( ...