33892-67-0Relevant academic research and scientific papers
Hydroaminoalkylation/Buchwald-Hartwig Amination Sequences for the Synthesis of Novel Thieno- or Benzothieno-Annulated Tetrahydropyridines, Tetrahydroazasilines, and Tetrahydroazasilepines
Warsitz, Michael,Rohjans, Stefan H.,Schmidtmann, Marc,Doye, Sven
, p. 830 - 849 (2021)
New two-step procedures that include an initial regioselective intermolecular hydroaminoalkylation of 2-allyl-, 2-allyldimethylsilyl-, or 2-dimethyl(vinyl)silyl-substituted 3-bromothiophenes or 3-bromobenzothiophenes with secondary amines and a subsequent intramolecular Buchwald-Hartwig amination give direct access to structurally novel bicyclic heterocycles including tetrahydrothienopyridines, tetrahydrothienoazasilines, tetrahydrobenzothienoazasilines, and tetrahydrobenzothienoazasilepines. The hydroaminoalkylation reaction is catalyzed by a mono(aminopyridinato) titanium complex which delivers the branched hydroaminoalkylation products or in the case of vinylsilyl-substituted substrates, the use of a bis(aminopyridinato) titanium complex gives access to the linear regioisomers. While in the latter case, the hydroaminoalkylation products need to be purified prior to the palladium-catalyzed amination step, all other two-step sequences can be run as a one-pot procedure.
Highly diastereoselective radical cyclisations of chiral sulfinimines
Rochette, Elise M.,Lewis, William,Dossetter, Al G.,Stockman, Robert A.
supporting information, p. 9395 - 9397 (2013/10/01)
Chiral amines are formed by the highly diastereoselective intramolecular addition of alkyl and aryl radicals onto chiral mesityl sulfinimines.
Cope Rearrangement in the Thiophene Series
MacDowell, Denis W. H.,Purpura, Joseph M.
, p. 183 - 188 (2007/10/02)
The inability to observe Cope rearrangement at elevated temperature for diethyl α-allylphenylmalonate does not extend to the analogous systems resulting from replacement of the benzene ring by 2- and 3-thiophene nuclei.Thermal rearrangement of diethyl α-allyl-2-thienylmalonate (5) at 250-260 deg C for 12 h produces the expected Cope rearrangement product diethyl (3-allyl-2-thienyl)malonate (6) (49percent) accompanied by ethyl 6-carboethoxy-5,6-dihydro-4H-5-cyclopentathiopheneacetate (7) (28percent).The structural verification of 6 was obtained by degradation to 3-allyl-2-methylthiophene which was compared with an authentic sample obtained by synthesis.The structure of 7 was based on analogy.Similar results were observed with the 3-substituted analogues of 5, both diethyl (2-allyl-3-thienyl)malonate (14) and ethyl 4-carboethoxy-5,6-dihydro-4H-5-cyclopentathiopheneacetate (15) being formed.In this case the structure of 14 was verified by synthesis.Speculative mechanistic considerations are offered regarding the mode of transformation of 6 to 7 and 14 to 15.That the methine proton of the malonate substituent in 6 and 14 is involved in this transformation is seen by the inability of the appropriate methyl-substituted derivative of 6 to undergo thermal cyclization.
