Direkter Ylidtransfer auf Carbonylverbindungen und Heteroarene

Abstract

Power‐Transfer: Die Titelreaktion (siehe Schema) verläuft unter milden Bedingungen (Raumtemperatur, kurze Reaktionszeit) und liefert ausgehend von methylenaktiven und heteroaromatischen Verbindungen Sulfonium‐Ylide in einem einzigen Schritt und in sehr hohen Ausbeuten. Ein detaillierter Strukturvergleich einer Vielzahl von Yliden wird genutzt, um den Einfluss der Struktur auf die Reaktivität dieser Verbindungen zu diskutieren.

Effect of specialist decision-making on treatment strategies for colorectal liver metastases (Br J Surg 2012; 99: 1263–1269)

“…We then examined the scope of this simple yet highly effective procedure for the intramolecular preparation of bicyclic furans. Importantly, all the alkynyl sulfonium ylides employed as substrates could be readily accessed by direct ylide transfer in very high yields according to our previously reported procedure 8. Their stability towards chromatography and recrystallization along with their crystallinity renders them easily handled substrates for subsequent transformations.…”

“…Initial studies focused on the alkynyl sulfonium ylide 1 a , readily available by direct ylide transfer8 to the corresponding ketoester. Exposure of this compound to diverse gold(I) promoters led to sharply contrasting results (see the Supporting Information for details), and it was found that the simple combination of commercially available PPh 3 AuCl and AgSbF 6 led to quantitative conversion into the furofuranone 2 a at room temperature within 3 h 9…”

Sulfoxonium and Sulfonium Ylides as Diazocarbonyl Equivalents in Metal‐Catalyzed Insertion Reactions

“…The decomposition of diazo compounds in the presence of HBF 4 and sulfides generates sulfonium salts, which, after addition of base, lead to sulfonium ylides 36. Two interesting and direct methods for the synthesis of sulfonium ylides were described by Cook and Moffatt,37a and recently by Maulide and co‐workers 37b,37c. Maulide and co‐workers employed Martin's sulfurane for direct ylide transfer to ketones, diketones, and keto esters in very good yields and under mild conditions (Scheme ).…”

Gold‐Catalyzed Intermolecular Synthesis of Alkylidenecyclopropanes through Catalytic Allene Activation

“…We recently developed a new methodology to directly access stabilized sulfonium ylides in a single step, by a process termed ylide transfer. [5] Those compounds display unique reac-tivity and electronic features, lending themselves to interesting applications featuring gold catalysis, [6,7] including an unusual intramolecular olefin cyclopropanation through catalytic olefin activation. [8] Herein, we describe an intermolecular gold-catalyzed synthesis of alkylidenecyclopropanes employing sulfonium ylides and activated allenes, [9] as well as mechanistic studies on this transformation (Scheme 1b).…”