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Efficient asymmetric synthesis of α-alkylated 1,4-cyclohexanedione derivatives, important chiral building blocks in the synthesis of natural products

✍ Scribed by Dieter Enders; Anja Nühring; Jan Runsink

Publisher: John Wiley and Sons
Year: 2000
Tongue: English
Weight: 131 KB
Volume: 12
Category: Article
ISSN: 0899-0042
DOI: 10.1002/(sici)1520-636x(2000)12:5/6<374::aid-chir13>3.0.co;2-g

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✦ Synopsis

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 alpha-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.