Yeni kiral ligandların hazırlanması ve asimetrik sentezlerdeki uygulamaları
Küçük Resim Yok
Tarih
2010
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Ege Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Epiklorohidrinin halka açılması, organoçinko bileşiklerinin ? -sililoksi ketonlara diastereoseçimli anti-felkin katılması ve Henry (nitroaldol) reaksiyonu olmak üzere üç farklı asimetrik sentez reaksiyonu üzerinde çalışıldı.Epiklorohidrinin asimetrik halka açılması, ilk defa bir salisilaldehit türevi nükleofil kullanılarak, kiral Co(III)-salen katalizörleri varlığında % 90 enantiyomerik fazlalık (ef) ile gerçekleştirildi. Bu sayede kiral bir merkez içeren ve aynı zamanda yapısındaki aldehit ve alkil halojenür fonksiyonel grupları sayesinde pek çok reaksiyon için kullanışlı bir substrat literatüre kazandırıldı. Bu aldehit kullanılarak oxim, benzisoxazole, diol ve Schiff bazı türevleri sentezlendi.TIPS, TBS ve TES gibi hacimli koruyucu gruplar içeren ? -kiral ketonlara, dialkil çinko ve sübstitüe vinil çinko bileşiklerinin nükleofilik katılması yüksek verim ve diastereoseçimlilikle (> 20:1) anti-Felkin ürününü verecek şekilde gerçekleştirildi. Bu yöntem ile yüksek diastereoseçimli anti-Felkin ürünleri daha önce mümkün olmayan akiral bir organometalik bileşik sayesinde elde edildi.Yeni L-(+)-Aspargin türevi bir Schiff bazı ligandı sentezlendi ve enantiyoseçimli Henry (nitroaldol) reaksiyonunda katalizör olarak kullanıldı. Schiff bazı ligandı, L-(+)-Aspargin dimetil esterine Grignard katılmasıyla hazırlanan amin ile 2-hidroksi-1-naftaldehitin kondenzasyon reaksiyonu ile sentezlendi. Henry reaksiyonu koşulları optimize edildikten sonra farklı aromatik sübstitüe aldehitlere nitrometanın katılması yüksek verim ve enantiyoseçimlilikle gerçekleştirildi.Anahtar Kelimeler: Asimetrik sentez, kiral katalizör, epiklorohidrin, anti-Felkin katılması, ? -sililoksi keton, organo çinko bileşikleri, Henry (nitroaldol) reaksiyonu, Schiff bazı
Three different types of asymmetric synthesis reactions were investigated such as ring- opening of epichlorohydrin, diastereoselective anti-Felkin addition of organozinc reagents to ? -silyloxy ketones and Henry (nitroaldol) reaction.Asymmetric ring-opening of epichlorohydrin was performed for the first time using a salicylaldehyde derived nucleofile in the presence of chiral Co(III)-salen catalyst with 90% ee. In this way, a substrate containing a chiral center and thus also useful for many reactions with aldehyde and alkyl halide functional groups in it`s structure was added to the literature. Oxime, benzisoxazole, diol and Schiff base derivatives of this aldehyde were synthesized.Nucleophilic addition of dialkylzinc and organozinc reagents to ? -chiral ketones containing crowded protecting groups, such as TIPS, TBS and TES, was performed with high yields and diastereoselectivities (> 20:1) resulting with anti-Felkin addition. This method provides access to anti-Felkin addition products with high diastereoselectivity previously unavailable using achiral organometallic reagentsA new L-(+)-Asparagine derivative Schiff base ligand was synthesized and applied in the enantioselective Henry (nitroaldol) reaction as a catalyst. Schiff base ligand was prepared by the condensation of 2-hydroxy-1-naphtaldehyde and the amine synthesized using Grignard addition to L-(+)-Asparagine dimethyl ester. Addition of nitromethane to a variety of aromatic substituted aldehydes was performed with high yields and enantioselectivities (90% ee) after the reaction conditions were optimized.Key words: Asymmetric synthesis, chiral catalyst, epichlorohydrin, anti-Felkin addition, ? -silyloxy ketones, organozinc reagents, Henry (nitroaldol) reaction, Schiff base.
Three different types of asymmetric synthesis reactions were investigated such as ring- opening of epichlorohydrin, diastereoselective anti-Felkin addition of organozinc reagents to ? -silyloxy ketones and Henry (nitroaldol) reaction.Asymmetric ring-opening of epichlorohydrin was performed for the first time using a salicylaldehyde derived nucleofile in the presence of chiral Co(III)-salen catalyst with 90% ee. In this way, a substrate containing a chiral center and thus also useful for many reactions with aldehyde and alkyl halide functional groups in it`s structure was added to the literature. Oxime, benzisoxazole, diol and Schiff base derivatives of this aldehyde were synthesized.Nucleophilic addition of dialkylzinc and organozinc reagents to ? -chiral ketones containing crowded protecting groups, such as TIPS, TBS and TES, was performed with high yields and diastereoselectivities (> 20:1) resulting with anti-Felkin addition. This method provides access to anti-Felkin addition products with high diastereoselectivity previously unavailable using achiral organometallic reagentsA new L-(+)-Asparagine derivative Schiff base ligand was synthesized and applied in the enantioselective Henry (nitroaldol) reaction as a catalyst. Schiff base ligand was prepared by the condensation of 2-hydroxy-1-naphtaldehyde and the amine synthesized using Grignard addition to L-(+)-Asparagine dimethyl ester. Addition of nitromethane to a variety of aromatic substituted aldehydes was performed with high yields and enantioselectivities (90% ee) after the reaction conditions were optimized.Key words: Asymmetric synthesis, chiral catalyst, epichlorohydrin, anti-Felkin addition, ? -silyloxy ketones, organozinc reagents, Henry (nitroaldol) reaction, Schiff base.
Açıklama
Anahtar Kelimeler
Kimya, Chemistry
