title: Ring-opening/ring-closing protocols from nitrothiophenes: six-membered versus unusual eight-membered sulfur heterocycles through Michael-type addition on nitrobutadienes.
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.
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, Genova University, Via Dodecaneso 31, 16146 Genova, Italy.
authors.forename: Lara
authors.initials: L
authors.lastname: Bianchi
authors.forename: Gianluca
authors.initials: G
authors.lastname: Giorgi
authors.forename: Massimo
authors.initials: M
authors.lastname: Maccagno
authors.forename: Giovanni
authors.initials: G
authors.lastname: Petrillo
authors.forename: Fernando
authors.initials: F
authors.lastname: Sancassan
authors.forename: Elda
authors.initials: E
authors.lastname: Severi
authors.forename: Domenico
authors.initials: D
authors.lastname: Spinelli
authors.forename: Marco
authors.initials: M
authors.lastname: Stenta
authors.forename: Cinzia
authors.initials: C
authors.lastname: Tavani