55004-95-0Relevant articles and documents
Manganese-catalyzed dehydrogenative Csp3-Csp2coupling of imidazo[1,2-a]pyridines with methyl ketones
Yao, Hua,Zhong, Xiaoyang,Wang, Bingqing,Lin, Sen,Liu, Lichi,Yan, Zhaohua
, p. 3479 - 3483 (2021/05/03)
A Mn(ii)-catalyzed efficient C-H alkylation of imidazoheterocycles with methyl ketones has been developedviadehydrogenative C(sp3)-C(sp2) coupling which can serve as a novel approach toward hydrocarboxylated imidazolopyridines. The merit of this strategy is illustrated by excellent functional group tolerance and the use of cheap and readily available starting materials.
Electrocyclization reactions of 1-Aza- and 1-oxapentadienyl and -heptatrienyl cations: Synthesis of pyrrole and furan derivatives
Alickmann, Dirk,Froehlich, Roland,Maulitz, Andreas H.,Wuerthwein, Ernst-Ulrich
, p. 1523 - 1537 (2007/10/03)
Quantum chemical DFT calculations (B3LYP/6-31+G) have been used to gain insight into the conformational and energy properties of the 1-aza- and 1-oxapentadienyl and -heptatrienyl cations 1, 2, 3, and 4. The calculated thermodynamic and kinetic data of the ring-closure reactions giving the cyclic products 5-14 are reported and discussed with respect to the experimental results. Experimentally, synthetic routes to the α,β-unsaturated carbonyl compounds 24 and 27, each with a leaving group in the γ-position, have been developed. These compounds have been investigated with respect to their ability to undergo 1,5-electrocyclization reactions to yield 2,5-disubstituted furans 28 upon heating in the presence of acid, presumably through the intermediate formation of the 1-oxapentadienyl cations 2. From the corresponding imine 29a the pyrrole 30d was obtained after treatment with tetrakis (triphenylphosphane) palladium. In the presence of benzylamine and the Pd° catalyst, the corresponding pyrroles 30a-c were formed from 24 and 27. The homologous α,β,γ,δ-unsaturated carbonyl compounds 31 afforded 2-vinyl-substituted furans 32 upon heating with acid, and the 2-vinyl-substituted pyrroles 34 on treatment with benzylamine and the Pd catalyst. No seven-membered heterocyclic rings were formed. Surprisingly, the α,β-unsaturated carbonyl compounds with two phenyl substituents at the γ-position also provided pyrrole derivatives 40 through a formal dimerization. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
Formation of tetrahydrofuran derivatives and acetonylation of alkenes using carbon radicals derived from manganese(III) oxidation of diketene
Nishino, Hiroshi,Nguyen, Van-Ha,Yoshinaga, Shinji,Kurosawa, Kazu
, p. 8264 - 8271 (2007/10/03)
Oxidation of a mixture of diketene and a 1,1-diarylethene 1 with manganese(III) acetate dihydrate gave an equilibrium mixture of 5-hydroxy-2-pentanone 2 and a tetrahydrofuran-2-ol, which was subsequently dehydrated in glacial acetic acid to yield 4-penten-2-one 4 in good yield. A similar reaction in the presence of alcohols or amines afforded 2-alkoxy-2-methyltetrahydrofurans 5 or 3-acetyl-2-aminodihydrofurans 9 in moderate yields. Diketene reacted with manganese(III) acetate in the presence of nucleophiles, such as water and alcohols, to give a mixture of unconjugated manganese(III) enolate A and conjugated manganese(III) enolate B. Major products 4 and 5 were formed by the oxidation of the conjugated manganese(III) enolate B. Tetrahydrofurylideneacetates 3 and 7 derived from the unstable unconjugated enolate A were also obtained as minor products. The reaction pathways are discussed.
