Diastereoselectivity of cyclopropanation of substituted α-fluorostyrenes versus styrenes by different methods
| Autor: | Günter Haufe, Katharina Bartels, Benjamin Schinor |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Aqueous solution
010405 organic chemistry Chemistry Cyclopropanation Organic Chemistry Substituent 010402 general chemistry 01 natural sciences Biochemistry Medicinal chemistry 0104 chemical sciences Styrene Catalysis Inorganic Chemistry chemistry.chemical_compound Ethyl diazoacetate Environmental Chemistry Organic chemistry Carboxylate Physical and Theoretical Chemistry Selectivity |
| Zdroj: | Journal of Fluorine Chemistry. 203:200-205 |
| ISSN: | 0022-1139 |
| DOI: | 10.1016/j.jfluchem.2017.09.008 |
| Popis: | The diastereoselectivity of cyclopropanations of styrene and α-fluorostyrene with diazoacetate depends on the catalyst used and the presence or absence of the fluorine substituent. The Cu(acac) 2 catalyzed reaction of styrene with diazoacetate led to 3:1 selectivity in favor of trans -2-phenylcyclopropane carboxylate, while α-fluorostyrene gave a 1:1 mixture of cis/trans -isomers. A competition experiment proved that α-fluorostyrene reacted slower compared to styrene itself. With the bulkier tetraphenyl-iron(III)-porphyrin chloride as catalyst, 10:1 or 3:1 mixture, respectively, were obtained. An advantage of the latter protocol is the in situ formation of ethyl diazoacetate from ethyl glycinate hydrochloride in aqueous solution by diazotation avoiding the in-substance application of the potentially explosive ethyl diazoacetate. Accordingly, a series of diastereoisomeric ethyl 2-aryl-2-fluoro-cyclopropane carboxylates was synthesized from p - or m -substituted α-fluorostyrenes. |
| Databáze: | OpenAIRE |
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