Studies towards the synthesis of diazonamide A. Synthesis of the 4-(oxazol-5-ylmethyl) aryltryptamine fragment

Recent applications of the Suzuki–Miyaura cross-coupling reaction in organic synthesis

“…In this connection, Kamenecka 130b). 278,279 In a related study, Vedejs and co-workers also reported the synthesis of the macrocyclic core 292 of diazonamide A by using the SM reaction of an oxazolylindole triflate with an arylboronic acid followed by a Dieckmann-type condensation (Scheme 131). 280 Dawson et al have reported a stereospecific synthesis of the anti-HIV compounds michellamine A and C via the SM cross-coupling reaction.…”

Muscarine, imidazole, oxazole, thiazole, Amaryllidaceae and Sceletium alkaloids

“…57 The highly substituted 4-aryltryptamine 154 bearing the CDFG ring system of the natural product has been synthesized via a palladium catalyzed intermolecular coupling reaction. 58 Based on a modified Vilsmeier procedure for the synthesis of 3-(2-Nphthaloylacyl)indole derivatives, the GCDEF fragment 155 of diazonamide A has been prepared by a convenient route in multigram quantities. 59 All these approaches represent remarkable strategies for the synthesis of natural polyoxazole alkaloids.…”

Diazonamide studies. A direct synthesis of the indole bis-oxazole fragment from tri- and tetra-peptides using biomimetic oxidative cyclizations

“…13 As noted previously, the correct structure of diazonamide A 2 better fits a biosynthetic route in which the bicyclic core derives from modification of a TyrValTrpTrp tetrapeptide, 4 and Harran's own synthesis of the natural product involves the formation of the G-H-F-E aminal by an oxidative cyclization of a tyrosine derivative that likely mimics the biosynthesis. 9 In continuation of our own longstanding interest in diazonamide A 2, [14][15][16][17][18][19][20][21][22] which primarily involves the use of diazocarbonyl chemistry to construct strategic C-N bonds by rhodium carbene N-H insertion reactions, we were also intrigued by the possibility of a biomimetic route that involves the oxidative cyclization of the putative biosynthetic precursor, the TyrValTrpTrp tetrapeptide. We now report the full details of our endeavours in this area.…”