Keten asetallerin çeşitli reaksiyonları
Küçük Resim Yok
Tarih
2000
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Ege Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
m ÖZET KETEN ASETALLERÎN ÇEŞİTLİ REAKSİYONLARI ÖZGENER, Hüseyin Doktora Tezi, Kimya Bölümü Tez Yöneticisi : Prof.Dr.Levent YÜCEER Haziran 2000,154 sayfa Bazı şeker türevleri ile keten asetal 2,2-diklorometil-l,3-diokso- lenin verdiği reaksiyonlar üzerine çalışmalar yapıldı. Kullanılan şeker türevleri, 1,2-0-izopropiliden-cc-D-glukofuranoz, l,2-0-(S)-trikloro- etiliden-a-D-galaktofuranoz, 1,2-0-(R)-trikloroetiliden-a-D-glukofuranoz 1,2-0-(S)-trikloroetiliden-a-D-glvıkofuranoz, 1,2-3,4-di-O-izopropiliden- -a-D-galaktopiranoz, 5,6-0-izopropiliden-l,2-0-(S)-trikloroetiliden-a-D- -galaktofuranoz, l,2:4,5-di-0-izopropiliden-a-D-fruktopiranoz ve l,2:5,6-di-(9-izopropiliden-glukofuranoz bileşiklerini içine almaktadır. Bu reaksiyonlarda asit veya bazik katalizörler kullanıldığında ba şarısız olunmuştur. Fakat nötral şartlarda reaksiyonlar düzgün bir şekilde yürümektedir. Bu reaksiyonlarda nitro metan çok iyi bir çözgen olmakla beraber N,N-dimetilformamit gibi (düşük bazikliği olan) çözgenlerde kullanılabilmiştir. Ürünler 2-diklorometil-l,3-diokso- lan-2-il, orto esterleri olarak elde edildi. Bu tür orto esterlerin küçük alkollerle oluştuğu bilinmektedir. Fakat karbohidrat kimyasında bu tür ortoester oluşumları yenidir. Bu reaksiyonlarda primer hidroksil grup larında regioselektiflik gözlenmiştir. Bununla beraber sekonder hid roksil gruplarıyla da düşük verimde tepkime verdiler. Bu yeni orto ester türevleri asetil türevlerinin yardımıyla karakterize edildi. EldeIV edilen türevlerin çoğunun elemental analiz değerleri doğru sonuç vermiştir. Bazı bileşikler küçük miktarda safsızlık içermektedir. Bu yeni ortoester türevlerinin ve bunların asetil türevleri, proton ve karbon nmr, kütle spektroskopisi ve infrared spektroskopik yöntemleri ile belirlendi. Karbon 13 nmr spektroskopisi özellikle 120 ppm civarında ortoester karbon sinyallerini belirleyici oldu. Tüm spektroskopik çalışmalar beklenen yapılarla uyumlu sonuçlar verdi. Bu türevlerin karbohidrat kimyasında koruyucu grup olarak kullanılması beklenmektedir. 3-0-metU-5,64zopropiliden-l,2-C>-(S)-trikloroetiliden-a-D-galakto- furanoz'un keten asetalinin piridinyum asetat ile asetillenmesi de ayrıca incelenmiştir
ABSTRACT SOME REACTIONS OF KETENE ACETALS ÖZGENER, Hüseyin PhD Thesis, Chemistry Department Supervisor : Prof.Dr.Levent YÜCEER. Haziran 2000,' 154; page The reactions of the ketene acetal, namely 2,2-dichlorometihyl-l,3-dioxolene with sugar derivatives were studied. Thesugar derivatives used include, l,2-<9-isopropylidene- a-D-glucofuranose, l,2-0-(S)-trichloroethylidene-a-D-galactofuranose, 1,2-0-(R)--trichloroethylidene-cc-D-glucofuranose, 1,2-<9-(S)-trichloro- ethylidene-a-D-glucofuranose, l,2:3,4-di-<9-isopropylidene-a-D-galacto- pyranose, 5,6-0-isopropylidene-l,2-0-(S)-trichloroethylidene-a-D- galactofuranose, l,2:4,5-di-0-isopropylidene-a-D-fructopyranose and 1,2-5,6-di-O-isopropyliden-glucofuranose. The reactions were failed in the presence of the acidic or basic catalysts but preceeds smoothly in neutral medium. The best solvent was found to be nitromethane however other solvents such as N,N-dimethylformamide (although slightly basic) could also be used. The products are 2-dichloromethyl-l,3-dioxolane-2-yl ortho esters. These type of orthoesters are known to be formed from small alcohols but their formation in the carbohydrate chemistry is novel. In the reactions, some regioselectivity is observed for the primary hydroxyl groups however secondary hydroxyl groups can also reacts although the yields are very low. The new orthoester derivatives thus obtainedVI were characterised by their acetyl derivatives. Most of the derivatives gave correct elemental analysis results. Some of the compounds contained small amount of impurities. The spectroscopic studies of the new ortho ester derivatives and their acetyl derivatives involves proton and carbon n.m.r, mass spectroscopy and infrared spectroscopy. Carbon- 13 n.m.r spectroscopy was especially useful in determining the orthoester carbon signal near 120 ppm. All spectroscopic results were in accordance with the proposed structures. These derivatives are expected to be useful as protecting groups in the carbohydrate chemistry. A ketene acetal formation from 3-0-methyl-5,6-<9- isopropylidene- 1,2-0-(S)-trichloroethylidene-a-D-galactofuranose and acetylation of the formed ketene acetal with pyridinum acetate were also studied.
ABSTRACT SOME REACTIONS OF KETENE ACETALS ÖZGENER, Hüseyin PhD Thesis, Chemistry Department Supervisor : Prof.Dr.Levent YÜCEER. Haziran 2000,' 154; page The reactions of the ketene acetal, namely 2,2-dichlorometihyl-l,3-dioxolene with sugar derivatives were studied. Thesugar derivatives used include, l,2-<9-isopropylidene- a-D-glucofuranose, l,2-0-(S)-trichloroethylidene-a-D-galactofuranose, 1,2-0-(R)--trichloroethylidene-cc-D-glucofuranose, 1,2-<9-(S)-trichloro- ethylidene-a-D-glucofuranose, l,2:3,4-di-<9-isopropylidene-a-D-galacto- pyranose, 5,6-0-isopropylidene-l,2-0-(S)-trichloroethylidene-a-D- galactofuranose, l,2:4,5-di-0-isopropylidene-a-D-fructopyranose and 1,2-5,6-di-O-isopropyliden-glucofuranose. The reactions were failed in the presence of the acidic or basic catalysts but preceeds smoothly in neutral medium. The best solvent was found to be nitromethane however other solvents such as N,N-dimethylformamide (although slightly basic) could also be used. The products are 2-dichloromethyl-l,3-dioxolane-2-yl ortho esters. These type of orthoesters are known to be formed from small alcohols but their formation in the carbohydrate chemistry is novel. In the reactions, some regioselectivity is observed for the primary hydroxyl groups however secondary hydroxyl groups can also reacts although the yields are very low. The new orthoester derivatives thus obtainedVI were characterised by their acetyl derivatives. Most of the derivatives gave correct elemental analysis results. Some of the compounds contained small amount of impurities. The spectroscopic studies of the new ortho ester derivatives and their acetyl derivatives involves proton and carbon n.m.r, mass spectroscopy and infrared spectroscopy. Carbon- 13 n.m.r spectroscopy was especially useful in determining the orthoester carbon signal near 120 ppm. All spectroscopic results were in accordance with the proposed structures. These derivatives are expected to be useful as protecting groups in the carbohydrate chemistry. A ketene acetal formation from 3-0-methyl-5,6-<9- isopropylidene- 1,2-0-(S)-trichloroethylidene-a-D-galactofuranose and acetylation of the formed ketene acetal with pyridinum acetate were also studied.
Açıklama
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Anahtar Kelimeler
Kimya, Chemistry, Keten asetal, Ketene acetals, Orto esterler, Ortho ester, Reaksiyon, Reaction
