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Catalytic enantioselective cyclopropanation of olefins using N-salicylidene-4-amino[2.2]paracyclophane as an asymmetric ligand

โœ Scribed by Douglas S. Masterson; Tara L. Hobbs; Daniel T. Glatzhofer

Book ID
104424435
Publisher
Elsevier Science
Year
1999
Tongue
English
Weight
143 KB
Volume
145
Category
Article
ISSN
1381-1169

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โœฆ Synopsis

The chiral ligand " -N-salicylidene-4-amino 2.2 paracyclophane 1 was synthesized and resolved. Resolved 1 was ลฝ . complexed to copper II for use as an asymmetric catalyst for the cyclopropanation of selected styrenes and stilbenes by diazoesters. Conversions of styrenes to cyclopropanes were high, typically ) 90% but were less than 40% for the stilbenes. Enantioselectivity was observed for the cyclopropanation of all substrates used, ranging from 8% ee for 1,1-diphenylethylene with t-butyldiazoacetate to 41% for styrene with t-butyldiazoacetate. The origin of the differences in reactivity and enantioselectivity for this catalyst system with the different substraterdiazoester combinations is discussed with regard to a steric model.

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Catalytic asymmetric synthesis of second
Catalytic asymmetric synthesis of secondary alcohols using chiral cis-1-amino-2-hydroxy-1,2,3,4-tetrahydronaphthalene as chiral ligand
โœ Cristina M Bellucci; Antonio Bergamini; Pier Giorgio Cozzi; Angelo Papa; Emilio ๐Ÿ“‚ Article ๐Ÿ“… 1997 ๐Ÿ› Elsevier Science ๐ŸŒ English โš– 529 KB

The synthesis and resolution of cis-1-amino-2-hydroxy-1,2,3,4tetrahydronaphthalene 5 by a simple and straightforward methodology has been achieved. The homochiral aminoalcohol has been used in the catalytic reduction of ketones by means of BH 3 .SMe2 affording secondary alcohols in high enantiomeric