Synthesis of Natural Products and Related Compounds using Enyne Metathesis

Abstract

Since the molybdenum and ruthenium carbene complexes 1a and 1b were discovered by Schrock and Grubbs in 1990 and 1992, synthetic organic chemistry has progressed with the use of these complexes as the catalyst for olefin metathesis. It was found that the ruthenium carbene complex was also effective for enyne metathesis, which occurs between an alkene and an alkyne. Intramolecular enyne metathesis gives various cyclic compounds having a 1,3-diene moiety and cross-metathesis of an alkene with an alkyne is a useful method for the synthesis of a compound having a diene moiety. Furthermore, dienyne metathesis, ROM of cycloalkenynes or tandem reactions of enyne metathesis have been developed. Using these various enyne metatheses, complicated natural products have been synthesized via novel routes. The syntheses of natural products and related compounds using enyne metathesis are described.

Methodology for the Construction of the Bicyclo[4.3.0]nonane Core

“…This methodology has been applied to the synthesis of norrisolide [79]. Enyne metathesis has found an increasing interest in the synthesis of natural products (see Scheme 24) [80][81][82][83][84]. It has found significant use in the synthesis of larger ring systems [85][86][87][88][89] and hetereocyclic systems [90][91][92][93][94][95], but only occasionally in the synthesis of hydrindanes [96][97][98][99].…”

Towards Highly Active and Robust Alkyne Metathesis Catalysts: Recent Developments in Catalyst Design

“…[1,2] This Highlight is intended to showcase some recent developments in the catalyst design and spotlight the immense potential of this unique multi-bond-exchange reaction.Subsequent to the discovery of the Mortreux system consisting of [Mo(CO) 6 ] and phenol additives, [1, 3] Schrock and co-workers pioneered the development of metal alkylidyne complexes, such as the prototype neopentylidyne complex [Me 3 CC W(OCCMe 3 ) 3 ]. [2,4] Since then, a significant number of reports have appeared in the literature regarding the synthesis and applications of several molybdenum-and tungsten-based alkylidyne complexes, including solid-supported catalysts.…”

“…[1,2] This Highlight is intended to showcase some recent developments in the catalyst design and spotlight the immense potential of this unique multi-bond-exchange reaction.…”

“…[2,4] Since then, a significant number of reports have appeared in the literature regarding the synthesis and applications of several molybdenum-and tungsten-based alkylidyne complexes, including solid-supported catalysts. [2,[4][5][6][7][8][9] The Mo III trisamido species [Mo-(NArR) 3 ] (Ar = 3,5-dimethylphenyl, R = tert-butyl), initially developed by Cummins and co-workers, [5] has received particular attention, as it can serve as the precursor to metathesis-active catalysts, either by in situ activation using dichloromethane, [6] leading to the formation of mixed species such as [MoCl(NArR) 3 ] and [MoCH(NArR) 3 ], or by a reductive recycling approach [7] in the presence of excess of magnesium and R'CHCl 2 (R' = H, Me, Et) to generate the corresponding alkylidyne [Mo(CR')(NArR) 3 ]. The alkylidyne [Mo(CR')(NArR) 3 ] reacts with substituted phenols and generates highly active catalysts in situ and has been successfully employed in the synthesis of conjugated polymers and shape-persistent macrocycles with high efficiency.…”

Hoch aktive und belastbare Katalysatoren für die Alkinmetathese

“…[2,4] Seitdem wurde über die Synthese verschiedener (auch festphasengebundener) Molybdän-und Wolframalkylidinkomplexe und ihre Anwendungen berichtet. [2,[4][5][6][7][8][9] Das Molybdän(III)-Triamid [Mo-(NArR) 3 ] (Ar = 3,5-Dimethylphenyl, R = tert-Butyl) von Cummins und Mitarbeitern [5] nahm eine Sonderstellung als Vorstufe für aktive Metathesekatalysatoren ein, die entweder in situ durch Aktivierung mit Dichlormethan [6] in Form gemischter Spezies wie [MoCl(NArR) 3 ] und [MoCH(NArR) 3 ] oder nach Reduktion [7] [7b] Die Verknüpfung der drei Phenoleinheiten über Methylenbrücken an ein trigonal-pyramidal umgebenes zentrales Amin-Stickstoffatom kçnnte deren Koordination an das Mo-Zentrum verstärken. Einkristall-Rçnt- …”