Ring‐Opening/Ring‐Closing Protocols from Nitrothiophenes: Six‐Membered versus Unusual Eight‐Membered Sulfur Heterocycles through Michael‐Type Addition on Nitrobutadienes |
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| Authors: | Lara Bianchi Dr Gianluca Giorgi Prof Massimo Maccagno Dr Giovanni Petrillo Prof Fernando Sancassan Prof Elda Severi Dr Domenico Spinelli Prof Marco Stenta Dr Cinzia Tavani Dr |
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| Institution: | 1. Dipartimento di Chimica e Chimica Industriale, Genova University, Via Dodecaneso 31, 16146 Genova (Italy), Fax: (+39)?010‐353‐6118;2. Dipartimento di Chimica, Siena University, Via A. Moro, 53100 Siena (Italy);3. Dipartimento di Chimica “G. Ciamician”, Bologna University, Via Selmi 2, 40126 Bologna (Italy) |
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| Abstract: | When Ar is a low‐aromaticity homo‐ or heterosystem, the sulfonyl‐stabilized anion of nitrobutadienes 4 (which derive from the initial ring opening of 3‐nitrothiophene) undergoes a rather surprising addition onto the aromatic ring itself, thereby leading to the construction of an unusual eight‐membered sulfur heterocycle condensed with the original Ar ring. The competitiveness of such a pathway with respect to the formation of the thiopyran ring (i.e., addition onto the nitrovinyl moiety) is favored at low temperatures, thus revealing its nature as a kinetically controlled process. |
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| Keywords: | fused‐ring systems medium‐ring compounds nitrothiophenes ring expansion sulfur heterocycles |
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