Synthetic exploitation of the ring-opening of 3,4-dinitrothiophene. Access to 1,4-disubstituted 2,3-dinitro-1,3-butadienes and 2,3-diaminobutanes (original) (raw)
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2,3-Dinitro-1,3-butadienes: Versatile Building Blocks from the Ring-Opening of 3,4-Dinitrothiophene
Targets in Heterocyclic Systems: Chemistry and Properties, 2006
Since its discovery in 1968, the ring opening of 3,4-dinitrothiophene (1) with amines has represented the first step in a number of valuable synthetic pathways. As a matter of fact, the dinitrobutadienediamines (7 or 8) which smoothly form in ethanol at room temperature as a result of a clear example of the non-benzenoid behaviour of 1, are highly-functionalized unsaturated systems whose versatility as building-blocks has so far been exploited for the preparation of linear as well as of homo- and hetero-cyclic molecules. In particular, target heterocycles encompass pyrroles, pyrrolidines, isoxazolines, isoxazoles, oxadiazoles, triazoles: i.e. systems endowed with high potentialities both in synthesis and in pharmacology.
Tetrahedron, 1995
The reactions of 1,4-disubstituted 2,3-dinitro-1,3-butadienes la-g in THF with isocyanides XCH2NC (TosMIC, X = tosyl; TBICA, X = COOBu t) and DBU furnish good to moderate yields of 2,3-disubstituted 4ethynylpyrroles Sa-g or 6a-g. In the reaction of lg with TosMIC and DBU the nitrovinyl pyrrole 7g and the 3,3'dipyrrole 4g are also isolated as by-products. A mechanism involving sequential base-induced addition, elimination and cyelization steps is advanced to account for the formation of the isolated products.
Chemistry of dinitroacetonitrile—II
Tetrahedron, 1962
Addition of dinitroacetonitrile to carbonyl conjugated unsaturated systems was a generally successful reaction for the preparation of Michael adducts. The expected products were obtained with methyl acrylate, acrylamide, acrolein, butenone, methylene-bis-acrylamide, and N,N',N"-triacrylylperhydro-s-triazine. Acrylic acid gave three products: the normal adduct, the corresponding carbamyl derivative and its cyclic imide. Dinitrocyanoethanol was easily prepared by reaction of dinitroacetonitrile with formaldehyde and the acetate, trifluoroacetate, acrylate and methacrylate esters of this alcohol were characterized. Esterification with 3,5-dinitrobenzoylchloride, fumaryl chloride and succinyl chloride gave liquid esters which could not be purified. N-(2,2-Dinitro-2-cyanoethyl)amides could be prepared in relatively general fashion as the products of reaction of dinitroacetonitrile with N-methylolamides. The corresponding acetyl, benzoyl, acrylyl, methacrylyl and bis-urea derivatives are described. These compounds were sensitive toward hydrolysis. Alkylation of dinitroacetonitrile and its salts to give identifiable products was not generally successful. As special cases the C-allyl, O-methyl, C-t-butyl and N-t-butyl derivatives could be prepared and were characterized.
Tetrahedron, 2001
AbstractÐThe reactions between 1,2-bis(diethylamino)-2,3-dinitro-1,3-butadiene, easily obtainable by ring-opening of 3,4-dinitrothiophene with diethylamine, and arylmethylmagnesium chlorides in THF at 08C furnished good yields of (E,E,E)-1,6-diaryl-3-nitro-1,3,5hexatrienes. To explain the formation of the hexatrienes, a mechanism is advanced which involves, in particular, tautomerisation of the intermediate 1,6-diaryl-3,4-dinitro-2,4-hexadienes followed by base-induced elimination of nitrous acid. The electrocyclic disrotatory conversion of the hexatrienes into the corresponding 5,6-diaryl-2-nitro-1,3-cyclohexadienes was analysed by 1 H NMR spectroscopy and exploited for the high-yielding synthesis of 1,2-diaryl-4-nitrobenzenes employing, as oxidants, either DDQ or iodine in the presence of cyclohexene oxide as HI scavenger. q Scheme 1. Reagents and conditions: (a) Excess Et 2 NH (4 mol equiv.), EtOH, 0±258C; (b) RMgX (2.2 mol equiv.), THF, 08C; (c) Ice/excess HCl quenching.