Cycloadditions of vinylindoles with chiral carbodienophiles: the first asymmetric Diels-Alder reactions in the vinylhetarane series

Katalytische asymmetrische Desaromatisierungen

“…Reaktionen unter Beteiligung von Vinylindolen sind eine sehr nützliche Strategie zur Desaromatisierung von Indolen für den Aufbau von Carbazol-Gerüsten. [29a] Lange Zeit beschränkten sich die Fortschritte auf diesem Gebiet auf nichtenantioselektive Reaktionen [29,30]. 2008 entwickelten Bernardi, Ricci et al die erste katalytische asymmetrische Diels-Alder-Reaktion von 3-Vinylindolen.…”

Crystal Structure of 2-Methoxymethyl-1,3-dithiane 1,1,3,3-tetraoxide

“…1 A range of sulfon-containing dienophiles has been reported that acts as an acetylene equivalent in cycloaddition reactions. 2 The title molecule may be a useful starting material for preparing a new sulfon-containing dienophile.The title compound was prepared according to a literature method. 3 (1RS,2RS)-2-Methoxymethyl-1,3-dithiane-1-oxide (0.61 g, 3.69 mmol) was dissolved in dry diethylether (15 ml) at 273 K. Purified m-CPBA (m-chloroperoxybenzoic acid; 4.0 g, 18.4 mmol) in ether (20 ml) was added via a dropping funnel over 20 min.…”

“…1 A range of sulfon-containing dienophiles has been reported that acts as an acetylene equivalent in cycloaddition reactions. 2 The title molecule may be a useful starting material for preparing a new sulfon-containing dienophile.…”

“…2 The title molecule may be a useful starting material for preparing a new sulfon-containing dienophile.…”

Complete π‐Facial Stereoselectivity in the TiCl4‐Mediated [4 + 2] Cycloaddition of Cyclopentadiene to N,N′‐fumaroyldi[(2R)‐bornane‐10,2‐sultam]

“…More recently, Kim and Curran then minimized this aspects), preferring a generalized steric model based on a disguised 2,5-dimethylpyrrolidine system [26], while Oppolzer has suggested a twisted model, stressing the importance of the enoyl O=C-C=C dihedral angle [27]. To rationalize the thermal cycloaddition of nitrile oxides to la, Kim et al [28] conclude that Coulombic repulsions between the S=O(a) group and the incoming reagent are more important than steric interactions6); furthermore, a recent puzzling report, based on MMX calculations7) and 'H-NOE measurements, proposes an anti-SO,/C(O) and a s-trans-conformation of the C=C bond to explain the uncatalyzed cycloaddition of vinyl-indols to l a [31]*). Finally, the case of methacryloyl sultam is noteworthy, since the stereoselectivity of the catalyzed endo -attack of cyclopentadiene [33] is unexpectedly resulting from a presumably strongly twisted quasi-s-cis -conformation [22]').…”