Synthesis of Indolobenzazepinones by Application of an Isocyanide‐Based Multicomponent Reaction

Abstract

Application of a Ugi multicomponent reaction to oxo acids 4 allows the formation of potentially antimitotic indolobenzazepinones of type 5 in good yields of up to 72 %, whereas the same transformation from the starting substrate 6 gives access to analogues of paullone with yields of up to 89 %. The reaction could be applied to a wide range of isocyanides, thereby ensuring introduction of molecular diversity at the key C‐5 position. Use of cyclohexenyl isocyanide allows post‐condensation modifications, while careful choice of the amine and the indole protecting groups proved to be important for providing the deprotected compounds necessary for biological tests. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Synthesis of Azocino[5,4‐b]indoles via Gold‐Catalyzed Intramolecular Alkyne Hydroarylation

“…Indole‐annulated medium‐sized rings are important heterocyclic motifs occurring in both natural and synthetic products. Nitrogen‐containing seven‐ and eight‐membered rings are the most widespread1 and have been constructed employing various methods including intramolecular Friedel–Crafts alkylation,2 intramolecular radical cyclization,3 ring‐closing metathesis,3b,4 classical5 and oxidative6 Heck reaction, one‐pot/tandem processes,7 multi‐component approaches8 and ring‐expansion protocols 9. We have recently described the assembly of azocino[4,5,6‐ cd ]indoles and azepino[4,5‐ b ]indoles via an intramolecular reductive Heck reaction (formal hydroarylation of the triple bond) 10.…”

Unprecedented nucleophile-promoted 1,7-S or Se shift reactions under Pummerer reaction conditions of 4-alkenyl-3-sulfinylmethylpyrroles

“…However, after implementing this approach, an undesirable isomer was obtained [ 21 ]. Although a number of acid- [ 22 – 23 ] and metal-catalysed cascade processes [ 24 – 25 ] have been developed (for example, Pictet–Spengler [ 26 ] and Ugi-type reactions [ 27 ], the acyl radical cyclisations [ 28 ] and the 1,7-electrocyclisation of azomethine ylides or ring expansion sequences [ 29 ]), most of these approaches are ineffective for synthesising pyrrolo[3,2- c ]azepines. Recently, Echavarren and Beller reported a novel Au- or Pt-catalysed cycloisomerisation reaction of pyrrole-2-carboxamides that produces pyrrolo[2,3- c ]- and [2,3- d ]azepinones [ 30 – 31 ].…”

Isolation and synthesis of cryptosanguinolentine (isocryptolepine), a naturally-occurring bioactive indoloquinoline alkaloid

“…Since Boc proved to be an unsuitable protecting group for the advanced stages of the synthesis, 104 was exposed to TFA, resulting in the deprotection of the N-Boc group in 94% yield (105). 135 Aer trying different protecting groups, the authors selected the MOM group, which has minimum steric demand, to pursue the synthesis.…”