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Hydrogenation of cinchona alkaloids over supported Pt catalyst
Author(s) -
Szöllősi György,
Forgó Péter,
Bartók Mihály
Publication year - 2003
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.10268
Subject(s) - cinchonidine , cinchonine , chemistry , cinchona alkaloids , diastereomer , catalysis , cinchona , yield (engineering) , quinoline , asymmetric hydrogenation , enantioselective synthesis , organic chemistry , ketone , enantiomeric excess , noyori asymmetric hydrogenation , medicinal chemistry , materials science , metallurgy
The heterogeneous catalytic hydrogenation of two isomeric cinchona alkaloids, cinchonidine and cinchonine, was studied over Pt/Al 2 O 3 in 1N H 2 SO 4 solution under 100 bar H 2 at 25°C. Cinchonidine was transformed into two diastereomeric hexahydroderivatives by hydrogenation of ring A (with N) of the quinoline moiety (yield over 95%, diastereomeric ratio 2/3), whereas hydrogenation of cinchonine resulted in the formation of three products, the major one being formed by the hydrogenation of ring B (without N) (yield 60%). The isolated hexahydroderivatives were investigated by 1 H‐, 13 C‐NMR, 1 H‐ 1 H COSY, 1 H‐ 13 C HetCOSY, and NOESY spectroscopy and were used as modifiers in the heterogeneous enantioselective hydrogenation of ethyl pyruvate and as catalysts in the Michael addition of ethyl 2‐oxocyclopentanecarboxylate to methyl vinyl ketone. Chirality 15:S82–S89, 2003. © 2003 Wiley‐Liss, Inc.