Regioselective and stereoselective synthesis of epithiomethanoiminoindeno[1,2-b]furan-3-carbonitrile: heterocyclic [3.3.
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ORIGINAL ARTICLE
Regioselective and stereoselective synthesis of epithiomethanoiminoindeno[1,2‑b]furan‑3‑carbonitrile: heterocyclic [3.3.3]propellanes Alaa A. Hassan1 · Nasr K. Mohamed1 · Ashraf A. Aly1 · Hendawy N. Tawfeek1 · Stefan Bräse2,3 · Martin Nieger4 Received: 28 October 2019 / Accepted: 23 December 2019 © Springer Nature Switzerland AG 2020
Abstract Synthesis of heteropropellanes in one step: the reaction between dicyanomethylene-1,3-indanedione (CNIND) and N-substituted-2-(2,4-dinitrophenyl)hydrazinecarbothioamides, furnished (3aR,8bS,Z)-2-amino-9-substituted-10-(2-(2,4-dinitrophenyl) hydrazono)-4-oxo-4H-3a,8b-(epithiomethanoimino)indeno[1,2-b]furan-3-carbonitrile as a type of (2,4-dinitrophenyl)hydrazono[3.3.3]propellanes in good yields as single diastereomers. Structure determination and confirmation of the synthesized products have been achieved using various and modern spectroscopic techniques such as IR, NMR (1H NMR and 13C NMR), mass spectrometry, as well as X-ray crystal analysis. The X-ray structure data cleared that the molecule of 7a was crystalized as monoclinic, space group C2/c (no.15). Graphic abstract
Keywords Annulated compounds · Heterocyclization · Imine-enamine tautomerism · Nucleophilic addition · Furothiazolo[3.3.3]propellanes · Thiosemicarbazides
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11030-019-10027-8) contains supplementary material, which is available to authorized users. * Alaa A. Hassan [email protected] Extended author information available on the last page of the article
Introduction Many reviews have discussed the history, structural features, chemical synthesis, natural occurring as well as pharmaceutical and pharmacological activity of propellanes [1–4]. Propellanes—tricyclic molecules with one joint single
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bond—attracted the attention of researcher due to their electronic properties [5], chemical relativities due to ring strain [6] and biological activities [7]. Propellanes play an important role in bioorganic synthesis due to their occurrence in various biologically active compounds [3]. Several propellane exhibits antiviral [8], antifungal [9] and anticancer [10–13] activities. Propellanes containing an indole moiety have biological and medicinal properties [14–16]. However, heteroatom-substituted propellanes are rare molecules in contrast to their all-carbon counter parts. (1,3-Dioxo-2,3-dihydro-1H-inden-2-ylidene)propanedinitrile (CNIND) is π-acceptor, which has a high affinity toward electron rich compounds. Accordingly, its reactions with 1,3-dicarbonyl compounds and β-ketoesters under acidic conditions resulted in the formation of diastereoselective products (3aR,8bR)-10amino-11-cyano-2-methyl-4-oxo-4H-8b,3a-(epoxyetheno) indeno[1,2-b]furan-3-carboxylates [17] and (3aR,8bS)10-amino-11-cyano-2-methyl-1-(arylamino)-4-oxo-1,4dihydro-8b,3a-(epoxyetheno)indeno[1,2-b]pyrrole-3-carboxylates [18] as an indene[3.3.3]propellanes and oxa-aza[3.3.3] propellanes respectively.
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