Synthesis of 2-(3-Bromo-1,2,3,4-tetrahydro-1,4-epoxynaphthalen-2-yl)-2-hydroxy-5,5- dimethylcyclohexane-1,3-dione and Its Reaction with Silver Salts

Öz

The addition of dimedone to oxabenzonorbornadiene was performed using Mn(III)acetate in the presence of HBr. The intermediate formed was trapped by bromine. The product was reacted with AgNO3 and AgClO4 in acetic acid. The expected dihydrofuran derivative was not formed. Instead, a hydroxylated dimedone compound on α-carbon was isolated. The structures of the compounds synthesized were characterized by 1H, 13C and 2D-NMR spectroscopy.

The addition of dimedone to oxabenzonorbornadiene was performed using Mn(III)acetate in the presence of HBr. The intermediate formed was trapped by bromine. The product was reacted with AgNO3 and AgClO4 in acetic acid. The expected dihydrofuran derivative was not formed. Instead, a hydroxylated dimedone compound on α-carbon was isolated. The structures of the compounds synthesized were characterized by 1H, 13C and 2D-NMR spectroscopy.

Anahtar Kelimeler

• Mangan(III)acetate
• Dimedone
• Oxabenzonorbornadiene

Mangan(III)asetat Eşliğinde 2-(3-Bromo-1,2,3,4-tetrahidro-1,4-epoksinaftalen-2-il)-3-hidroksi-5,5-dimetilsiklohekze-2-enon’un Sentezi ve Gümüş Tuzları İle Reaksiyonu

Öz

Mn(III)asetat eşliğinde dimedonun oksabenzonorbornadiene katılma reaksiyonundaki ara ürün HBr ile yakalandı. Katılma ürünü AgNO₃ ve AgClO₄ ile asetik asit içerisinde reaksiyona sokuldu. Beklenen dihidrofuran halkası oluşmadı. Bunun yerine dimedondaki α-karbonunun hidroksillendiği bileşik oluştu. Sentezlenen bileşiklerin yapıları ¹H, ¹³C ve 2D-NMR teknikleri ile karakterize edildi.Geçiş metallerinin tuzları yardımı ile oluşturulan karbon radikallerinin çift bağlara katılması, organik kimyada karbon-karbon bağının oluşturulmasında önemli yöntemlerden birisidir[1]. En yaygın kullanılanı ise Mn(III)asetat’tır. Heiba ve Dessau, Mn(III)asetat ile yapmış oldukları çalışmalarda gösterdiler ki asetik asit içerisinde alkenlere 1,3- dikarbonil bileşiklerinin katılmasıyla dihidrofuranlar oluşmaktadır[2] (Şekil 1). Oksidatif olarak elde edilen radikal 2 çift bağ karbonuna katılarak yeni radikal 3 oluşur. İlgili radikal (3) yükseltgenerek karbokatyon 4 oluşabilir ve halkalaşma sonrası proton kaybetmesiyle dihidrofuran oluşabilir (Rota A). Ya da radikal 3 önce halkalaşarak radikal 5’i ardından proton kaybetmesiyle dihidrofuran oluşturabilir (Rota B) [3,4].

Anahtar Kelimeler

• Mangan(III)asetat
• Dimedon
• Oksabenzonorbornadien

Kaynakça

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3. [3] (a) Corey, E., Kang M. 1984. New and general synthesis of polycyclic γ-lactones by double annulation. Journal of the American Chemical Society, 106, 5384-5385. (b)Fristad, W. E., Peterson, J. R., Ernst A. B. 1985. Manganese(III)-mediated γ-lactone annulation with substitued acids. The Journal of Organic Chemistry, 50, 3143-3148.
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7. [7] Fristad, W. E., Peterson, J. R., Ernst, A. B., Urbi, G. B. 1986. Mechanisms for manganese(III) oxidations with alkenes, Tetrahedron, 42, 3429-3442.
8. [8] Çalışkan, R., Ali, M. F., Şahin, E., Watson, W., Balci M. 2007. Unusual manganese(III)-mediated oxidative free-radical additions of 1,3-dicarbonyl compounds to benzonorbornadiene and 7-heterobenzonorborna-dienes: Mechanistic studies. The Journal of Organic Chemistry, 72, 3353-3359.

9. [9] Whitesides, G. M., Filippo J. S. 1970. The mechanism of reduction of alkylmercuric halides by metal hydrides, Journal of the American Chemical Society, 92, 6611-6624.
10. [10] Dengiz, C., Çalışkan, R., Balci M. 2012. Chloroacetonylation of C=C double bonds promoted by manganese(III) acetate. Tetrahedron Letters, 53: 550-552.
11. [11] Zeigler, G. R. 1969. Mechanism of Photochemical reaction in solution LVII. The Photorearrangement of 1,4-dihydronaphthalene to benzo [f] oxepine. Journal of the American Chemical Society, 91, 446-449.