Osmium‐Catalyzed 7‐endo Heterocyclization of Aromatic Alkynols into Benzoxepines

Abstract

Os im Katalysator, O im Heterocyclus: Regioselektive osmiumkatalysierte 7‐endo‐Heterocyclisierungen aromatischer Alkinole liefern Benzoxepine in guten Ausbeuten. Der vorgeschlagene Katalysezyklus umfasst die Bildung eines Osmium‐Vinyliden‐Komplexes über einen Alkinyl‐Hydrid‐Osmium(IV)‐Komplex aus der Ausgangsverbindung.

Ruthenium‐Catalyzed Cycloisomerization of Aromatic Homo‐ and Bis‐Homopropargylic Amines/Amides: Formation of Indoles, Dihydroisoquinolines and Dihydroquinolines

“…However, to the best of our knowledge the use of this approach in the synthesis of isoquinolines and quinolines has not been described. As part of our ongoing program devoted to the synthesis of biologically active heteroaromatic compounds using commercial or easily available metal catalysts, [8] herein we present new Ru-catalyzed 5-endo and regioselective 6-endo heterocyclizations (cycloisomerizations) of aromatic homo-and bis-homopropargylic amines/amides to give indoles, dihydroisoquinolines and dihydroquinolines in good-to-excellent isolated yields (Scheme 2).…”

An Efficient Approach for the Construction of Benzazepine and Benzoxepine Derivatives

“…However, the poor substrate sustainability and high temperatures restricted the prospects of this methodology. Recently, Saá and co‐workers disclosed an osmium‐catalyzed 7‐ endo heterocyclization of aromatic alkynols into benzoxepines, which was only suitable for the terminal alkynes 11. Therefore, the development of an efficient strategy toward the preparation of benzazepine and benzoxepine derivatives is highly desirable.…”

Eight-Membered Rings With One Oxygen Atom

“…171 The synthesis of 3-benzo[d]oxocine 218 was achieved through regioselective osmium-catalyzed 8-endo heterocyclization of 3-(2ethynylphenyl)propan-1-ol 217 in pyridine at 130 C for 4 h, in moderate yield (40%) (Scheme 33, path a). 172,173 Further derivatives 220 were obtained from similar substrates 219 under the presence of low loading of a ruthenium complex 221 (Scheme 33, path b). 174 Regioselective reductive cyclization of alkynyl diol 222 using stoichiometric amount of Hg(OTf ) 2 and triethylsilane prompted pyran-fused oxocane 223, via 8-endo oxacyclization process (Scheme 34).…”