- Platinum-Catalyzed Desaturation of Lactams, Ketones, and Lactones
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The development of a general platinum-catalyzed desaturation of N-protected lactams, ketones, and lactones to their conjugated α,β-unsaturated counterparts is reported. The reaction operates under mildly acidic conditions at room temperature or 50 °C. It is scalable and tolerates a wide range of functional groups. The complementary reactivity to the palladium-catalyzed desaturation is demonstrated in the efficient conversion of iodide, bromide, and sulfur-containing substrates.
- Chen, Ming,Rago, Alexander J.,Dong, Guangbin
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supporting information
p. 16205 - 16209
(2018/11/23)
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- Catalytic, asymmetric vinylogous Mukaiyama aldol reactions of pyrrole- and furan-based dienoxy silanes: How the diene heteroatom impacts stereocontrol
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Denmark's chiral bisphosphoramide/silicon tetrachloride system performs as an excellent Lewis base-Lewis acid catalyst for the vinylogous Mukaiyama aldol reaction of pyrrole- and furan-based dienoxy silanes with aromatic and heteroaromatic aldehydes. This asymmetric methodology provides a powerful synthetic entry to a variety of d-hydroxylated g-butenolide-type frameworks with high efficiency and valuable margins of regio-, diastereo-, and enantioselectivity. Notably, the nature of the heteroatom within the vinylogous dienoxy silane donor heavily impacts the diastereocontrol, with syn-configured aldol adducts emerging from pyrroles bearing electron- withdrawing N-protecting groups (Boc, Ts, and Cbz) and anti-configured adducts prevailing when furan- or N-alkyl/alkenylpyrrole donors are involved.
- Curti, Claudio,Ranieri, Beatrice,Battistini, Lucia,Rassu, Gloria,Zambrano, Vincenzo,Pelosi, Giorgio,Casiraghi, Giovanni,Zanardi, Franca
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supporting information; experimental part
p. 2011 - 2022
(2010/11/17)
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- A novel and one-pot synthesis of new 1-tosyl pyrrol-2-one derivatives and analysis of carbonic anhydrase inhibitory potencies
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Here we propose a novel one-pot synthesis of new tosyl-pyrrole derivatives. By means of the new developed method, pyrrole derivatives were synthesized at room temperature in a single step, and a useful method is proposed for the synthesis of similar compounds. Moreover, inhibitions of two human cytosolic carbonic anhydrase (hCA, EC 4.2.1.1) isozymes I and II by 1-tosyl-pyrrole and 1-tosyl-pyrrol-2-on derivatives were investigated. 1-Tosyl-pyrrole, 1-tosyl-1H-pyrrol-2(5H)-one, 5-hydroxy-1-tosyl-1H-pyrrol-2(5H)-one and 5-oxo-1-tosyl-2,5-dihydro-1H-pyrrol-2-yl acetate showed inhibitory action with Ki values in the range of 14.6-42.4 μM for hCA I and 0.53-37.5 μM for hCA II, respectively. All pyrrole derivatives were competitive inhibitors with 4-nitrophenylacetate as substrate. Some new synthesized pyrrole derivatives showed very effective hCA II inhibitory effects, in the same range as the clinically used sulfonamide acetazolamide, and might be used as leads for generating enzyme inhibitors targeting other CA isoforms.
- Alp, Cemalettin,Ekinci, Deniz,Gueltekin, Mehmet Serdar,Sentuerk, Murat,Sahin, Ertan,Kuefrevioglu, Oemer Irfan
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experimental part
p. 4468 - 4474
(2010/08/22)
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- Dichloroketene-induced cyclizations of vinyl sulfilimines: Application of the method in the synthesis of (±)-desoxyeseroline
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The reactions of several aryl-, furanyl-, and vinyl-substituted sulfilimines with dichloroketene proceeded at 25 °C to yield thioalkyl-substituted γ-lactams. The overall process involves nucleophilic addition of the nitrogen atom of the sulfilimine onto the highly electrophilic dichloroketene to first generate a zwitterionic intermediate. A subsequent [3,3]-sigmatropic rearrangement is followed by intramolecular trapping of the Pummerer cation by the amido anion to furnish the observed γ-lactam product. Incorporation of donor groups on the aromatic ring of the sulfonyl functionality had little effect when aryl-substituted sulfilimines were used but exhibited a major effect on the efficiency of the reaction with furanyl-substituted systems. The placement of an electron donor group (i.e., OMe) on the sulfonyl aryl group enhances the nucleophilicity of the amido anion contained within the sulfonium ion intermediate and facilitates the rate of the 3,3-sigmatropic rearrangement. Styryl-substituted sulfilimines cyclize in a stereospecific manner and produce a 3:2-mixture of γ-lactams and the isomeric imino-lactone system. The heavily functionalized γ-lactams are easily converted to a variety of nitrogen containing substrates. The vinyl sulfilimine cyclization method was applied to the total synthesis of the Calabar alkaloid (±)-desoxyeseroline.
- Padwa, Albert,Nara, Shinji,Wang, Qiu
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p. 8538 - 8549
(2007/10/03)
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- A new synthesis of γ-lactams based on the reaction of vinyl sulfilimines with dichloroketene
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(Chemical Equation Presented) The reactions of several aryl-, furanyl-, and vinyl substituted sulfilimines with dichloroketene proceeded at 25°C to yield thioalkyl substituted γ-lactams which, in turn, were converted to a variety of nitrogen-containing substrates.
- Wang, Qiu,Nara, Shinji,Padwa, Albert
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p. 839 - 841
(2007/10/03)
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