Silicon tetrachloride mediated asymmetric aldol addition reaction

Tan, Duygu
Aldol addition reaction is one of the most important and most studied carbon-carbon bond forming reactions in organic chemistry. Recent studies focused on the catalytic version of this chemistry. Different from the classical Mukaiyama-type aldol reactions, chiral lewis bases have been used as promoters. In the presence of SiCl4, these reactions proceed through a cyclic transition state leading to anti aldol product as a major product with moderate-to-good diastereo and enantioselectivities. Phosphoramide derivatives, BINAPO, BINAPO derivatives, N,N-dioxides and N-oxides have been extensively used for this purpose. Recently, our group has designed new phosphine oxy aziridinyl phosphonates (POAP) as chiral Lewis bases. These promoters were used for the asymmetric aldol addition reaction between cyclohexanone and different aldehydes in the presence of SiCl4. Moreover, our previously designed phosphine oxy ferrocenyl substituted aziridinyl methanol (POFAM) ligands were also tested as Lewis bases. Among these 6 potential promoters, POAP-A gave the best results, and the aldol product were obtained in moderate to good yields up to 80%, and with moderate enantioselectivities (the highest, 66%) after standard optimization studies. Aldehyde screening experiments provided the highest enantioselectivity (68%) with 2- naphthaldehyde.


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Carbon-nitrogen bond formation is one of the most important reactions in organic chemistry. Various synthetic strategies for the generation of C-N bonds are described in the literature. For example, primary amines can be easily synthesized by the thermal decomposition of an acyl azide to an isocyanate, i.e. the Curtis rearrangement, followed by hydrolysis; the Curtius rearrangement has been used extensively. Furthermore, the advantage of the Curtius rearrangement is the isolation of acyl azides as well as t...
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Radical cyclization of alkenes is one of the most important methods for the synthesis of cyclic compounds. The one electron oxidant Mn(OAc)3 has been used for many years for the oxidative addition of acetic acid to alkenes to give lactones. In this thesis, various alkenes substituted at 1,2-positions by phenyl and thiophene rings were reacted with active methylene compounds in the presence of Mn(OAc)3∙2H2O. The regioselectivity of the addition were searched. The mechanism for the addition was studied in con...
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The first part of the thesis presents the KMnO4/ carboxylic acid/ organic solvent which is a powerful reagent for C-C bond formation, aryl coupling reactions and enone oxidation. The a¢-acetoxylation of enones and the a-acetoxylation of aromatic ketones were carried out with potassium permanganate and acetic acid, in which acetoxylation products were obtained in 74-96% yields. The same reaction was carried out with carboxylic acids other than acetic acid, which furnished corresponding acyloxy ketones with t...
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Functionalization of oxabenzonorbornadiene: Manganese(III)-mediated oxidative addition of dimedone
ÇALIŞKAN, Raşit; Sari, Ozlem; Balcı, Metin (Wiley, 2017-09-01)
3-Chloro-1,2,3,4-tetrahydro-1,4-epoxynaphthalen-2-yl)-3-hydroxy-5,5-dimethylcy-clohex- 2-en-1-one, synthesized by the reaction of oxabenzonorbornadiene with Mn(OAc)(3) and dimedone in the presence of HCl in acetic acid, was submitted to ring-opening reactions with BBr3 and H2SO4. Reaction with BBr3 yielded 2 products, a 5-membered ring and an 8-membered ring, with the former being the major product. However, the H2SO4-supported reaction exclusively formed an 8-membered ring. The mechanism of formation of th...
Citation Formats
D. Tan, “Silicon tetrachloride mediated asymmetric aldol addition reaction,” M.S. - Master of Science, Middle East Technical University, 2013.