Olefinlerden fatolotik yolla tek aşamalı alfa, beta- doymamış karbonil bileşikleri sentezi
One-pot conversion of olefinsto alfa, beta-unsaturated carbonyl conpounds
- Tez No: 39838
- Danışmanlar: PROF.DR. OLCAY ANAÇ
- Tez Türü: Yüksek Lisans
- Konular: Kimya, Chemistry
- Anahtar Kelimeler: Karbonil kompleksler, Metil sübstitüe sikloheksenonlar, Olefinler, Sentez, Carbonyl complexes, Methyl substitue cyclohexanes, Olefines, Synthesis
- Yıl: 1994
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: Belirtilmemiş.
Özet
ÖZET Metil sübstitüe sikloheksenonlar canlıların salgılarında da bulunabilen önemli doğal bileşiklerdir. Kozmetik, parfüm ve ilaç endüstrilerinde kullanılabilirlik özellikleriyle sentezleri önem kazanmıştır ve çoğu sentez reçeteleri patentlerle korunmuştur. Bu derece yararlı çıkış bileşiklerinin sentezlerinde bir çok sorunla karşılaşılmaktadır. Bu sorunlar çok aşa malı reaksiyonlar, düşük verim, pahalı ve güç elde edilen çıkış maddelerinin kullanılması şeklinde özetlenebilir. Çalışmamızın amacı tek aşamalı olan“Metil sübstitüe sikloheksenin singlet oksijen ile fotolitik reaksiyonu ”ile metil sübstitüe sikloheksenonların sentezini incelemektir. Her aşamada ele geçen ürünlerin analizleri Gaz Kromatografisi ve ince Tabaka Kromatografisi ile gerçekleştirilmiş, tanımlanmalar ise IR-Spektroskopisi ve zaman zaman ^-NMR Spektroskopisi ile yapılmıştır. vı
Özet (Çeviri)
There are few compounds that have more potential and versatility in organic synthesis than cyclic and acylic a,/3-conjugated carbonyl compounds. The a,£-unsaturated carbonyls behave as dienophiles in the Diels Alder reaction. They react with guanidine to give pyrimidines, hydroxylamine to give isoxazeles, hydrazine to give pyrazoles and hydrazoic acid to give 1,2, 3-triazoles. The a,J3-unsaturated ketones exhibit a wide variety of addition reactions, some reagents adding to the carbonyl group, others adding to the carbon-carbon double bond, whilst some, e.g. Grignard reagents, may add to the conjugated systems with subsequent rearrangement ; 0 OMqBr II I y RCCH=CHR + R“MgBr> RC=CHCHR'R”0 H70 II -» RCCH2CHR'R“ Halogens and halogen acids add to the double bound in the latter case the halogen atom usually becaming attached to the J3-carbon atom. Another important group of addition reactions comprises the Michael addition of compounds, such as malonic, cyonoacetic and acetoacetic acid esters, easily capable of yielding carbanions in the presence of catalytic quantities of alkali. o o RCH=CHCR' + CH2(COOEt)2 Na0Et > RCHCH2CR' CH(COOEt)2 VllThe a,/3-unsaturated carbonyl compounds useful as perfumes, medicines. Yet the available sources of these valuable materials are generally tedious, multistep synthetic routes or expensive commercial suppliers. The starting compounds for the synthesis of a, J3- conjugated carbonyl compounds are alkenes, cycloalkenes, ketones, diesters. Although several different reaction patways are available for the synthesis of these conjugated carbonyls no approach has been generally applicable to the simple C-5 through C-8 cycloalkenes. In our study 1,5-cyclooctadien, 1-decen, 1-methyl-l- cyclohexen, 4 -methyl -1 -eye lohexen, 3 -methyl -1-cyclohexen, were used as starting compounds for the synthesis of carbonyl compounds by an in situ photooxygenation elimination procedure. Our synthesis is based on the decades-old observations of Schenck and co-workers, which demonstrated that allylic hydroperoxides are handily prepared by reaction of alkenes with photochemically generated singlet oxygen and these materials are easily converted to enones under mild conditions. The cycloalkenes, exemplified by 1 -methyl- 1-cyclohexen as shown in Scheme I, are readily photooxygenated in the presence of acetic anhydride and base to yield directly cycloalkenones after aqueous work up and distillation. O2. AC2O, Pyridine 4-Dimethylaminopyridine CH2C12 '0, V) a CO s X OH ^k^OOH Ac70 + u -. Base OOAc OOAc Scheme I -Photooxygenation of 1-methyl-l-cyclohexen. Vlll02 ^A^yOOH Ac,0 /”^yOOAc ^~yO * u Base »L> +U OÜH CH2=CH(CH2)7CH3 OOAc 02 * CH2CH=CH(CH2)6CH3 0 Ac20 Base CH2CH=CH(CH2)6CH3 z^> H-CCH=CH(CH2)6CH3 f\ 102 |-^yOOH J^yOOH Ac20 J^yOOAc \^ > k^J + k J Base J L J + 1 Jl 0 r^N-OOAc Base > ^N^w Is^J -HOAc <P '0< Ac20 OOH Base OOH Base ^ jl -HOAc* 0 *0 OOH % 1 0, f^yOOH OOAc o Base) f^f° -HOAc l^Jk + Ac20 Base OOAc ^yOQAc Scheme II- Direct Synthesis of a,0-unsaturated Carbonyl Compounds from Olefins. IXThe examples shown in Scheme II illustrate that this one-pot method is general and useful in a preparative sense. Furthermore, it has been applied to a variety of cyclic and acyclic olefins to produce a,£-unsaturated ketones, aldehydes and esters. The acylation catalyst, 4- (dimethyl amino) pyridine, was incorporated into the general procedure to hasten these steps of the conversion. The completion of reactions were controlled by gas chromatographic and thin layer chromatographic analysis of samples taken from the reaction mixtures. The products were identified by their IR spectra and in some cases ^-NMR Spectra. Clearly, the success of this reaction lies in the lack of reactivity of the intermediates as well as the product to the photooxygenation conditions. It is also interesting to note that only a catalytic amount of base is required to effect the conversions. The good to excellent yields reflect the lack of formation of significant side products. Liquidphase oxidation reactions (either enzymatic or spontaneous ) play an important role in the oxidative degradation of various materials and living organisms. These processes involve the reaction of free radicals with atmosphere (or ground state) oxygen. Ground state oxygen has two electrons in two separate orbitals. The angular momentum of these electrons is opposed but they have parallel spins. On the other hand, the first excited state of oxygen (i.e, C^Ag) or singlet oxygen has both electrons in a single orbital in which the angular momentum is the same, a characteristic which makes singlet oxygen a very reactive molecule. Single oxygen has a half life in aqueous solvents, of 2 to 5u second an energy of approximately 22 kcal above ground oxygen.^g J_ \_ 37 kcal/mol % JJ, 22 kcal/mol 3Sg 1 1 22 kcal/mol Photosensitized generation of singlet oxygen has been utilized in the study of certain organic oxidation reactions. A dissolved dye sensitizer is electronically excited by the absorption of visible light. The excited sensitizer than transfer its additional energy to groundstate oxygen present in the solution. Sen> :Sen :Sen> 3Sen 2Sen> Sen + 02 {lkg) Singlet oxygen can react with various substrates in three different ways: 1-1,4-Cycloaddition with conjugated dienes, frequently resulting in the generation of endoperoxides (B). 2-1,2-Cycloaddition, a reaction that occurs when olefins and enamines react with 02(lbs) with formation of 1,2- dioxetanes ( C ). 3- An“ene”reaction, with olefins having two or more alkyl substituents, to form allylic hydroperoxides (A). xx~s-<^~ 0H 00 -x>- c0 -^ - s: XIX
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