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Diastereoselective alkylation of 8-phenylmenthyl 2-methylacetoacetate. Preparation of enantiomerically pure 4,4-disubstituted 2-pyrazolin-5-ones

✍ Scribed by Marcial Moreno-Mañas; Rosa M. Sebastián; Adelina Vallribera; Elies Molins; Enrique Espinosa

Publisher
Elsevier Science
Year
1997
Tongue
English
Weight
127 KB
Volume
8
Category
Article
ISSN
0957-4166

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✦ Synopsis

Alkylation of (lR,3R,4S)-8-phenylmenthyl 2-methylacetoacetate with alkyl halides affords 2-alkyl-2-methylacetoacetates in diastereomeric ratios 72:28 to 85:15. The major R (at C-cx) diastereoisomers are converted into enantiopure 4,4-disubstituted 2pyrazolin-5-ones with recovery of the chiral inductor.

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