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Nucleophilic Acylation of 3,4‐Dihydroisoquinolinium Salts. Diastereoselective Synthesis of the Protoberberine Alkaloid (±)‐Corydaline and of Analogous Compounds
Author(s) -
Tietze Lutz F.,
Brill Gunter
Publication year - 1987
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.198719870327
Subject(s) - chemistry , nucleophile , acylation , medicinal chemistry , hydrolysis , yield (engineering) , enamine , enol , nucleophilic addition , organic chemistry , stereochemistry , catalysis , materials science , metallurgy
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 ( 2 ≡ 19b ) in 84% yield.