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Efficient asymmetric synthesis of α‐alkylated 1,4‐cyclohexanedione derivatives, important chiral building blocks in the synthesis of natural products
Author(s) -
Enders Dieter,
Nühring Anja,
Runsink Jan
Publication year - 2000
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/(sici)1520-636x(2000)12:5/6<374::aid-chir13>3.0.co;2-g
Subject(s) - chemistry , alkylation , enantiomer , acetal , electrophile , hydrazone , organic chemistry , oxalic acid , cleavage (geology) , stereochemistry , catalysis , geotechnical engineering , fracture (geology) , engineering
Alkylation of 1,4‐cyclohexanedione monoethylene acetal SAMP‐hydrazone with various electrophiles (10 examples given) and subsequent cleavage of the hydrazones with saturated oxalic acid furnished highly enantiomerically enriched α‐alkylated mono‐protected 1,4‐cyclohexanedione derivatives in high yields and enantiomeric excesses of ee = 28, 80–≥99%. Reduction of the ketones gave the corresponding alcohols in good yields with high enantiomeric excesses ( ee = 80–≥98%) and cis / trans ‐ratios of usually 85:15. Chirality 12:374–377, 2000. © 2000 Wiley‐Liss, Inc.