Iodo- and bromo-enolcyclization of 2-(2-propenyl)cyclohexanediones and 2-(2-propenyl)cyclohexenone derivatives using iodine in methanol and pyridinium hydrobromide perbromide in dichloromethane.
alpha-Allylcyclohexane-1,3-diones undergo one-pot iodine-methanol promoted iodocyclization and oxidative aromatization to afford variously substituted 2-iodomethyltetrahydrobenzofuran-4-ones (minor) and 2-iodomethyl-4-methoxydihydrobenzofuran derivatives (major). On the other hand, the alpha-allyl-1,3-cyclohexanediones react with pyridinium hydrobromide perbromide in dichloromethane to afford mixtures of 2-bromomethyltetrahydrobenzofuran-4-ones (major) and 3-bromomethyltetrahydrobenzopyran-5-ones (minor). The prepared products and their derivatives were characterized using a combination of NMR, FT-IR and mass spectroscopic techniques.
Mphahlele
Malose J
MJ
Department of Chemistry, College of Science, Engineering and Technology, University of South Africa, P.O. Box 392, Pretoria, 0003, South Africa. mphahmj@unisa.ac.za
Moekwa
Thwanthwadi B
TB
D000498:Allyl Compounds / Q000138:chemical synthesis*; D001578:Benzopyrans / Q000138:chemical synthesis*; D001965:Bromides / Q000737:chemistry; D001966:Bromine / Q000737:chemistry*; D003500:Cyclization; D003512:Cyclohexanones / Q000138:chemical synthesis*; D018054:Hydrobromic Acid / Q000737:chemistry; D007455:Iodine / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry; D008752:Methylene Chloride / Q000737:chemistry; D010084:Oxidation-Reduction; D011726:Pyridinium Compounds / Q000737:chemistry*
D000498:Allyl Compounds; D001578:Benzopyrans; D001965:Bromides; D003512:Cyclohexanones; D011726:Pyridinium Compounds; D018054:Hydrobromic Acid; D008752:Methylene Chloride; D007455:Iodine; D001966:Bromine; D000432:Methanol