- Synthesis of Polycyclic Indolines by Utilizing a Reduction/Cyclization Cascade Reaction
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Subsequent reduction and dearomatizing cyclization reactions open up an entry into the synthesis of novel N-fused polycyclic indolines. The dearomatizing cyclization as key step of the sequence proceeds well with Cu(OTf)2 or TfOH as catalyst. At elevated temperature reduction of nitro-substituted precursors with iron under acidic conditions affords a broad variety of polycyclic indolines directly in a two-step cascade reaction in good to excellent yields. Using the developed protocol, the alkaloids tryptanthrin and phaitanthrin C have been prepared.
- Zhang, Jingyu,Xia, Wei,Qu, Meilin,Huda, Saskia,Ward, Jas S.,Rissanen, Kari,Albrecht, Markus
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supporting information
p. 6097 - 6101
(2021/11/09)
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- Transition-Metal-Free and Visible-Light-Mediated Desulfonylation and Dehalogenation Reactions: Hantzsch Ester Anion as Electron and Hydrogen Atom Donor
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Novel approaches for N- and O-desulfonylation under room temperature (rt) and transition-metal-free conditions have been developed. The first methodology involves the transformation of a variety of N-sulfonyl heterocycles and phenyl benzenesulfonates to the corresponding desulfonylated products in good to excellent yields using only KOtBu in dimethyl sulfoxide (DMSO) at rt. Alternately, a visible light method has been used for deprotection of N-methyl-N-arylsulfonamides with Hantzsch ester (HE) anion serving as the visible-light-absorbing reagent and electron and hydrogen atom donor to promote the desulfonylation reaction. The HE anion can be easily prepared in situ by reaction of the corresponding HE with KOtBu in DMSO at rt. Both protocols were further explored in terms of synthetic scope as well as mechanistic aspects to rationalize key features of desulfonylation processes. Furthermore, the HE anion induces reductive dehalogenation reaction of aryl halides under visible light irradiation.
- Heredia, Micaela D.,Guerra, Walter D.,Barolo, Silvia M.,Fornasier, Santiago J.,Rossi, Roberto A.,Budén, Mariá E.
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supporting information
p. 13481 - 13494
(2020/12/15)
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- Hg(OTf)2-Catalyzed cycloisomerization of 2-ethynylaniline derivatives leading to indoles
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Cycloisomerization of 2-ethynylaniline derivatives catalyzed by mercuric triflate afforded indole derivatives in excellent yield under mild reaction conditions with high catalytic turnover up to 100 times.
- Kurisaki, Takahiro,Naniwa, Tomoko,Yamamoto, Hirofumi,Imagawa, Hiroshi,Nishizawa, Mugio
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p. 1871 - 1874
(2008/02/05)
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- 2-Sulfonyl-4-chloroanilino moiety: a potent pharmacophore for the anti-human immunodeficiency virus type 1 activity of pyrrolyl aryl sulfones.
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The synthesis and the evaluation of cytotoxicity and anti-HIV-1 activity of new aryl pyrrolyl (8) and aryl indolyl (9) sulfones are reported. Preparation of above sulfones was achieved by reacting arylsulfonyl chlorides with substituted pyrroles and indoles or by condensing sulfonamides with 2,5-dimethoxytetrahydrofuran in glacial acetic acid according to the Clauson-Kaas method. Chemical requisites relevant to the anti-HIV-1 activity of these compounds are both a 2-sulfonyl-4-chloroanilino moiety and an alkoxycarbonyl group at position 2 of the pyrrole ring. The best activity and selectivity were obtained with ethoxycarbonyl and isopropoxycarbonyl substituents. Substitutions at the amino group of the pharmacophore moiety led to inactive products (alkylation) or weakened (acylation) anti-HIV-1 activity. Among test derivatives, 16 compounds showed EC50 values ranging between 10 and 1 microM, and five (8b',d',f',h'j') showed EC50S in the sub-micromolar range. The compounds were active against HIV-1, both wild type and AZT-resistant strains, but not against HIV-2. Moreover, in enzyme assays they potently inhibited the HIV-1 recombinant reverse transcriptase, were 10 times less active against enzymes from nevirapine- and TIBO-resistant strains, and were totally inactive against the HIV-2 recombinant enzyme. Interestingly, some compounds (8r'-y') were inactive against the recombinant reverse transcriptase while being active in tissue culture.
- Artico, Marino,Silvestri, Romano,Massa, Silvio,Loi, Anna G.,Corrias, Simona,et al.
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p. 522 - 530
(2007/10/03)
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