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Chiral Lactols, XIV. Stereoselective Fusion of Five‐Membered Ring Lactols to the Bornane Ring System
Author(s) -
Noe Christian R.,
Knollmüller Max,
Gärtner Peter,
Mereiter Kurt,
Steinbauer Gerhard
Publication year - 1996
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199619960623
Subject(s) - chemistry , stereoselectivity , ring (chemistry) , lactol , lactone , hydrolysis , oxalate , reagent , enantiopure drug , zinc , medicinal chemistry , catalysis , stereochemistry , organic chemistry , enantioselective synthesis
Condensation of d ‐camphor ( b ) with diethyl oxalate and subsequent ester hydrolysis yielded camphoroxalic acid 3 . endo ‐Fused lactone 9 was obtained by reduction of 3 with zinc followed by reduction with NaBH 4 and ring closure with H 2 SO 4 . exo ‐Fused lactone 16 , the crystal structure of which was determined, was prepared by reduction of 3 with NaBH 4 under basic conditions followed by catalytic hydrogenation and ring closure with HCl. Reduction of 9 and 16 with DI‐BALH and application of acidic work‐up conditions yielded the self‐condensed reduction products (lactol anhydrides) 10 and 17 , which are useful reagents in racemate resolution and stereoselective synthesis.