Oxindoles from Phalaris coerulescens

Transition‐Metal‐Mediated Routes to 3,3‐Disubstituted Oxindoles through Anilide Cyclisation

“…When 18 was treated with Pd 2 (dba) 3 and Et 3 N in PhMe, a mixture of 19a and 19b (89:11 in favour of 19a) was obtained (Table 1, Entry ii). The opposite stereoselectivity was observed when Et 3 N was replaced with Ag 3 PO 4 (Table 1, Entry iii).…”

“…[29,31] Further investigations also showed the utility of the Heck reaction for the construction of 3-alkyl-3-aryl oxindoles. [32] Overman and co-workers were also successful in the preparation of a variety of cyclotryptamine alkaloids, containing multiple pyrrolidino [2,3]indole subunits (Scheme 6). [33] Members of this family of natural products prepared by total synthesis include meso-and (-)-chimon-Scheme 6.…”

“…In addition, the direct carbonylation of the aryl-Pd intermediate to give 60 had to be suppressed. This was largely achieved by use of Pd 2 (dba) 3 , the electron-rich trifurylphosphane, substoichiometric 4-dimethylaminopyridine (DMAP) and 1,4-diazabicyclo[2.2.2]octane (DABCO). Use of these conditions furnished compound 58 in 55 % yield along with a 6 % yield of the unexpected byproduct 61 (which presumably arises by re-addition of a palladium hydride intermediate into the Heck product 59 and subsequent carbonylation/ester formation).…”

“…Among the simple natural products containing an oxindole moiety are horsfiline (1) [2] and coeresculine (2). [3] Welwitindolinone A isonitrile (3) [4] and rhynchophylline (4) [5] possess more complex spirocyclic systems in addition to the oxindole ring. Examples of 3-heteroatom-substituted oxindoles are also found in nature.…”

Natürliche Pyrrolidinylspirooxindole als Vorlagen für die Entwicklung medizinischer Wirkstoffe

“…Die verwandte Verbindung Coerulescin (2 b), die eine noch einfachere Struktur aufweist, wurde 1998 isoliert; ihre Synthese wird oft zusammen mit der von Horsfilin beschrieben. [5] Chitosenin (3) ist ein weiterer Naturstoff mit interessanter Struktur, der in vivo bei Ratten und Kaninchen eine kurzlebige inhibitorische Aktivität gegenüber der ganglionären Transmission zeigt. [6] Strychnofolin (4) inhibiert die Mitose bei mehreren Zelllinien, einschließlich Mausmelanom B16, Ehrlich und Hepatom HW165.…”