Diazo Compounds and Phenyliodonium Ylides in the Inter- and Intramolecular Cyclopropanations Catalyzed by Dirhodium (II): Synthesis and Chiral Resolution by GC versus HPLC

Ashraf Ghanem, Fabienne Lacrampe, Hassan Aboul-Enein, Volker Schurig

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The dirhodium(II)-catalyzed intermolecular cyclopropanation of a set of olefins with either diazo free phenyliodonium ylides or diazo compounds afforded cyclopropanes derived from Meldrum’s acid, dimethyl malonate, (silanoxyvinyl)diazoacetates, 3,3,3-trifluoro-2-diazopropionate, ethyl diazo(triethyl)- and (dimethylphenyl)silylacetate with moderate to high yield in either racemic or enantio-enriched forms. The intramolecular cyclopropanation of triethylsilyl-substituted allyl diazoacetates in the presence of the chiral rhodium(II) catalyst [Rh2(s-nttl)4] in toluene afforded the corresponding cyclopropanes with up to 37% ee. An efficient chiral separation method based on enantioselective GC and HPLC was developed. The method provides information about the chemical yields of the cyclopropane products, enantioselectivity, substrate specifity, and catalytic activity of the chiral catalysts used in the inter- and intramolecular cyclopropanation reactions and avoids timeconsuming work-up procedures.
Original languageEnglish
Pages (from-to)1205-1219
Number of pages15
JournalA U M L A
Volume136
Issue number47
DOIs
Publication statusPublished - 2005
Externally publishedYes

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