Manganese(iii)acetate-based free-radical additions of -dicarbonyl compounds to bicyclic systems

Fedalla, Mohammad Ali
Additions of carbon-centered radicals to alkenes are useful method for cyclic compounds formation. Manganese(III)-based oxidative free-radical cyclizations, where the radicals are generated and terminated oxidatively, are established as efficient methods for the construction of cyclic molecule. Treatment of a mixture of dimedone, Mn(OAc)3, and Cu(OAc)2 in glacial acetic acid with homobenzonorbornadiene (80) (4h at 50 C) gave furan derivative (107), dihydrofuran adduct (108), in addition to rearranged product (109) as a major product. The reaction run under the same reaction conditions without using Cu(II)acetate for 8h afforded dihydrofuran adduct (108) along with dihydrofuran (110), where no rearranged products could be formed. On the other hand, reflux of alkene 80 with a mixture of acetylacetone, Mn(OAc)3, and Cu(OAc)2 in glacial acetic acid (3h at 50 C) gave oxidative product (131) and rearranged product (132) (major). The reaction run under the same reaction conditions without using Cu(II)acetate for 7h produced, in addition to the oxidative product 131, a dihydrofuran derivative (133). In a second system, we examined the oxidation of benzobarrelene 82 with Mn(OAc)3, and Cu(OAc)2 in glacial acetic acid (1h at 50 C) in presence of dimedone resulted in the formation of five different products rearranged products (148, 149) and a dihydrofuran (109), besides, a mixture containing two major rearranged isomers (150/151). The same reaction was carried out under the same conditions in absence of Cu(II) for 9h and gave the isomeric mixture 150/151 exclusively, and the yield was reduced. The oxidative cyclization of acetylacetone with alkene 82 for 3h at 50 C, afforded in addition to the dihydrofuran (132), two rearranged products (169, 170) and a mixture consisting of two isomers (171/ 172). The isomeric mixture was converted to one product by treatment with methanolic ammonia providing hydroxyl derivative which was oxidized by MnO2 to afford product 174 in a good yield. Additionally, we investigated the behavior of nitrogen bridge in the bicyclic system on the course of the reaction. Oxidation of N-carbethoxy-7-aza-2,3-benzonorbornadiene 83 with dimedone in the presence of Cu(OAc)2 as well as in its absence in glacial acetic acid (2h at 50 C), rearranged product (189) was obtained as the sole product. Regarding the reaction of aza-derivative 83 with acetylacetone in the presence of Cu(OAc)2 (18 h at 50 C), rearranged product 195 was resulted as sole product. The reaction of 83 was also run with out Cu(OAc)2 for 22h and gave the rearranged product 195.


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The synthesis of a set of naphthazarin-containing polycyclic conjugated hydrocarbons is described herein. Sequential Diels-Alder reactions on a tautomerized naphthazarin core were employed to access the final conjugated systems. Complete conjugation across the backbone can be achieved through complexation with BF2, as observed by (HNMR)-H-1 analysis and UV/vis spectroscopy. Precise synthetic control over the degree of oxidation of naphthazarin quinone Diels-Alder adduct 10 is additionally demonstrated and e...
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Some phenolic biphenyl compounds have been synthesised via the annulation reactions of 4-methoxy-2- pyrone with various active methyl compounds.
Chemoenzymatic synthesis of chiral hydroxymethyl cycloalkenols
Şenocak, Deniz; Demir, Ayhan Sıtkı; Department of Chemistry (2004)
Chiral cyclic alkenols with hydroxymethyl functionality are important structural units in many biologically active natural compouds such as prostaglandins, sesquiterpene antiviral agents, pentenomycins, xanthocidin, sarkomycin, etc. 1,3-cycloalkanediones are converted into bicyclic polyoxo derivatives with formaldehyde and trioxane in the presence of Lewis acid. Selective oxidation of the bicyclic compounds by using manganese(III)acetate followed by enzyme-catalyzed kinetic resolution afforded chiral bicycl...
Generation of acyl anion equivalents from acylphosphonates via phosphonate-phosphate rearrangement: A highly practical method for cross-benzoin reaction
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Acylphosphonates are potent acyl anion precursors that generate acyl anion equivalents under the promotion of cyanide anion via phosphonate-phosphate rearrangement. These anions readily react with aldehydes to provide cross-benzoin products. In this way it is possible to synthesize a variety of aromatic-aromatic, aromatic-aliphatic, and aliphatic-aromatic benzoins. Moreover the reaction of benzoylphosphonate with potent electrophile 2,2,2-trifluoroacetophenone provided the corresponding aldehyde-ketone coup...
Asymmetric synthesis of N-aryl substituted chiral 1,4-aminoalcohol derivatives and applications in various asymmetric transformation reactions
Odabaş, Serhat; Tanyeli, Cihangir; Department of Chemistry (2007)
The asymmetric synthesis of N-aryl substituted chiral 1,4-aminoalcohols and their applications in asymmetric borane reduction and enantioselective diethylzinc addition to benzaldehyde reactions were performed starting from meso-anhydride 51 that is the cycloadduct of cyclopentadiene and maleic anhydride. The desymmetrization of meso-anhydride 51 was achieved by using quinine or quinidine with very high enantiomeric excess value (up to 98% ee) and with high chemical yield. The quinine-mediated desymmetrizati...
Citation Formats
M. A. Fedalla, “Manganese(iii)acetate-based free-radical additions of -dicarbonyl compounds to bicyclic systems,” Ph.D. - Doctoral Program, Middle East Technical University, 2007.