Asymmetric Synthesis and Catalysis

Pentaphenylcyclopentadienyl ruthenium complexes (3) are excellent catalysts for the racemization of secondary alcohols at ambient temperature. The combination of this process with enzymatic resolution of the alcohols results in a highly efficient synthesis of enantiomerically pure acetates at room temperature with sho…

• FİLİZ BETÜL KAYNAK

This review summarizes the trends in the formation of complex or not so complex heterocyclic structures through 1,3-dipolar cy­cloadditions of azomethine ylides. Diastereo- and enantioselective processes as well as non-asymmetric cycloadditions constitute very important synthetic tools for achieving these compounds. T…

• HACI ALİ DÖNDAŞ

Masked acyl cyanide (MAC) reagents are shown to be effective umpolung synthons for enantioselective Michael addition to substituted enones. The reactions are catalyzed by chiral squaramides and afford adducts in high yields (90-99%) and with excellent enantioselectivities (85-98%). The addition products are unmasked t…

• YUNUS EMRE TÜRKMEN

Ferrocenyl-substituted aziridinylmethanol (Fam-1) was used as a catalyst with zinc for the asymmetric nitroaldol (Henry) reaction. This catalyst worked with a variety of aldehydes (aromatic, aliphatic, alpha,beta-unsaturated, and heteroaromatic) and alpha-ketoesters to give the nitroaldol product in up to 97% yield an…

Ferrocenyl-substituted aziridinylmethanol (Fam-1) was used as a catalyst with zinc for the asymmetric nitroaldol (Henry) reaction. This catalyst worked with a variety of aldehydes (aromatic, aliphatic, alpha,beta-unsaturated, and heteroaromatic) and alpha-ketoesters to give the nitroaldol product in up to 97% yield an…

• ÖZDEMİR DOĞAN

[reaction: see text] A new chiral aziridino alcohol ligand for zinc(II)-catalyzed azomethine ylide cycloadditions is described. In the presence of this catalyst, N-arylidene glycine methyl esters react with a variety of dipolarophiles to give substituted pyrrolidines in very good to excellent chemical yields and up to…

[reaction: see text] A new chiral aziridino alcohol ligand for zinc(II)-catalyzed azomethine ylide cycloadditions is described. In the presence of this catalyst, N-arylidene glycine methyl esters react with a variety of dipolarophiles to give substituted pyrrolidines in very good to excellent chemical yields and up to…

• ÖZDEMİR DOĞAN

The Sc(OTf)3-catalyzed (3 + 2)-annulation of donor-acceptor cyclopropanes and ynamides is described, providing the corresponding cyclopentene sulfonamides in good to excellent yield. Deprotection and hydrolysis of the resulting ensulfonamides delivers 2,3-substituted cyclopentanones with high diastereoselectivity.

• MERYEM FISTIKÇI EŞSİZ

[reaction: see text] Various ferrocene-based organosilanols have been synthesized in four steps starting from achiral ferrocene carboxylic acid. Applying these novel planar-chiral ferrocenes as catalysts in asymmetric phenyl transfer reactions to substituted benzaldehydes afforded products with high enantiomeric exces…

Proline-thiourea host-guest complex-catalyzed direct enantioselective aldol reactions have been developed, in which the catalytic activities were evaluated in the direct asymmetric aldol reactions of various aromatic aldehydes and cyclohexanone.

• SERKAN EYMUR

A general, metal-free, highly enantioselective Brønsted acid catalyzed [3+2] cycloaddition between hydrazones and alkenes has been developed that affords pyrazolidine derivatives (see scheme). The resulting optically active pyrazolidines can undergo many chemical transformations which allow, for example, the enantiose…

• HATİCE BAŞPINAR KÜÇÜK

A novel class of chiral 5,5'-di(2,4,6-trialkyl)aryl salen-metal complexes have been developed and shown to catalyze highly enantioselective Nazarov cyclization reactions, giving rise to cyclopentenoids in 90:10-98:2 er. Significantly, the catalysts also promote, for the first time, highly enantioselective Nazarov reac…

• YUNUS EMRE TÜRKMEN