Diastereoselective Pt Catalyzed Cycloisomerization of Polyenes to Polycycles

Abstract

Application of a tridentate NHC containing pincer ligand to Pt catalyzed cascade cyclization reactions has allowed for the catalytic, diastereoselective cycloisomerization of biogenic alkene terminated substrates to the their polycyclic counterparts.

Biomimetic Platinum-Promoted Polyene Polycyclizations: Influence of Alkene Substitution and Pre-cyclization Conformations

“…Previously reported substrate 1 was synthesized through Johnson’s classic three step sequence involving the addition of isopropenyl magnesium bromide to an aldehyde, mercury trifluoroacetate catalyzed vinylation and Claisen rearrangement. 9 Although the analogous vinyl magnesium bromide protocol does not successfully yield the desired 1,2-alkene fragments, a one pot vinylation/Claisen rearrangement using (1,10-phenanthroline)Pd(OAc)2 and triethyleneglycol divinylether (TGDV) was effective. 10 In combination with the Johnson Claisen reaction, this method provided the desired mix of stereochemically defined di- and tri-substituted alkene precursors for synthesis of 2–4 (see Supporting Information for details).…”

Terpenoid Biosynthesis Off the Beaten Track: Unconventional Cyclases and Their Impact on Biomimetic Synthesis

“…[49] Several successful attempts have been made to mimic biosynthetic pathways by using various agents to trigger the cyclization of linear precursors, such as Brønsted acids, Lewis acids, UV light, [67] transition metals such as Ir, [68] Pt, [69] and Au, [70] and also more exotic materials such as zeolites [71] and antibodies. [49] Several successful attempts have been made to mimic biosynthetic pathways by using various agents to trigger the cyclization of linear precursors, such as Brønsted acids, Lewis acids, UV light, [67] transition metals such as Ir, [68] Pt, [69] and Au, [70] and also more exotic materials such as zeolites [71] and antibodies.…”

Terpenoid‐Biosynthese abseits bekannter Wege: unkonventionelle Cyclasen und ihre Bedeutung für die biomimetische Synthese

“…stark 49. Es gab mehrere erfolgreiche Versuche zur Nachahmung von Biosynthesewegen, bei denen verschiedene Agentien zum Auslösen von Cyclisierungen linearer Ausgangsverbindungen eingesetzt wurden, darunter Brønsted‐Säuren, Lewis‐Säuren, UV‐Licht,67 Übergangsmetalle wie Ir,68 Pt69 und Au,70 aber auch exotischere Materialien wie Zeolithe71 und Antikörper 72. Da die meisten dieser Methoden bereits gut etabliert und umfassend rezensiert sind,49, 73 soll sich dieser Abschnitt mehr um die aktuelleren Entwicklungen auf dem Gebiet der Synthese drehen.…”