Diamine ligands cyclopropanation

Asymmetric Cyclopropanation of Styrene. New chiral copper catalysts A or B bearing secondary 1,2-diamine ligands (eq 29) were obtained from Cu(OTf)2 (1 mol%), and 1S,2S)-N,N-di(mesitylmethyl)-l,2-diphenyl-l,2-ethanediamine (2-3 mol%), depending upon the molar ratio of ligand to Cu(OTf)2 employed. 

Diamine-derived chiral copper complex 254 was used in the asymmetric cyclopropanation (Scheme 1.120) [177]. Perlluorinated diamine ligand 255 was developed and showed moderate levels of enantioselectivity for the cyclopropanation of diazoacetate (Scheme 1.121) [178]. The fluorous ligand was readily separated by the simple decantation of the fluorous phase. Although the recycling of the catalyst was expected, reuse was difficult because of its partial decomposition. 

Other bis(sulfonamides) ligands based on more flexible diamines have been investigated by Denmark et al. as promoters for the enantioselective Simmons-Smith cyclopropanation of cinnamyl alcohol. This study has revealed a... 

Like BINOL, salicylaldehyde imines have become very important in asymmetric catalysis and a variety of polydentate ligands prepared from chiral monoamines and diamines are employed in oxidation reactions, carbenoid reactions and Lewis acid catalyzed reactions. As in the previous section, this section emphasizes the effect of the phenol moiety on the asymmetric catalysis. An imine derived from a chiral 1-phenethylamine and salicylaldehyde was employed in the copper catalyzed asymmetric cyclopropanation by Nozaki, Noyori and coworkers in 1966, which is the first example of the asymmetric catalysis in a homogeneous system . Salicylaldehyde imines with ethylenediamine (salen) have been studied extensively by Jacobsen and Katsuki and their coworkers since 1990 in asymmetric catalysis. Jacobsen and coworkers employed the ligands prepared from chiral 1,2-diamines and Katsuki and coworkers sophisticated ligands possess chirality not only at the diamine moiety but also at the 3,3 -positions. 

Recently, another cobalt(II)/camphor-derived complex was developed for performing the asymmetric cyclopropanation of olefins [38]. The complex 18 was prepared by reacting the ligand 17, synthesized by condensation of (lR)-3-hydroxymethylenebornane-2-thione and the corresponding diamine, with co-balt(II) dichloride hexahydrate in degassed ethanol (Scheme 11). The cyclopropane derivatives were obtained in 50-60% yield using 3 mol % of the catalyst 18 and ethyl diazoacetate in styrene or 1-octene as solvent. The diastereomeric ratios were low for both styrene and 1-octene. 

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