Cycloisomerization Promoted by the Combination of a Ruthenium–Carbene Catalyst and Trimethylsilyl Vinyl Ether, and its Application in The Synthesis of Heterocyclic Compounds: 3‐Methylene‐2,3‐dihydroindoles and 3‐Methylene‐2,3‐dihydrobenzofurans

Abstract

Transition-metal-catalyzed cyclization of a,w-dienes is an efficient method for the construction of carbo-and heterocycles. One particularly interesting cyclization is olefin metathesis, [1] in which significant progress was made after the development of well-defined ruthenium-carbene catalysts, such as A and B (Scheme 1). In particular, the commercially available ruthenium-carbene catalyst B has shown enhanced activity in ring-closing metathesis (RCM), ring-opening metathesis polymerization (ROMP), and cross metathesis (CM). [1c, 2] On the other hand, the nonmetathetic behaviors of ruthenium-carbene catalysts have been demonstrated in recent studies of olefin metatheses.[3] When a substrate cannot give a product by metathesis, nonmetathetic reactions, such as the Kharasch addition, [4] olefin isomerization, [5] and hydro-

Hybrid Organic‐Inorganic Materials Derived from a Monosilylated Hoveyda‐type Ligand as Recyclable Diene and Enyne Metathesis Catalysts

“…1 H and 13 C NMR of 16 were coincident with that described for this compound in the literature. [30] The solid catalyst 9d was dried and reused in the next run.…”

Five‐Membered Heterocycles: Benzofuran and Related Systems

“…Several 2,3-dihydrobenzo [b]furans can be made by the Ru-catalyzed olefin metathesis approach in the presence of trimethylsilyl vinyl ether (Scheme 7.52) [87]. The isovanillin derived benzo [b]furan has also been synthesized by the C-propenylation-O-vinylation and olefin metathesis approach [88].…”

Development of Environmentally Benign Organometallic Catalysis for Drug Discovery and Its Application

“…Hence, we initially attempted to determine the structure of actual active ruthenium species, for the isomerization of terminal olefin as well as the cycloisomerization of diene, under various conditions using Schlenck technique. 22) However, strong support for our working hypothesis came from the reaction performed in a glovebox, which kept the oxygen and moisture concentrations below 1 ppm. We finally found that the reaction of E with 61a gave ruthenium hydride (A) in quantitative yield (Chart 12).…”

“…For more than ten years, we have been exploring a synthetic methodology for nitrogen-containing heterocycles using these ruthenium carbene catalysts and applying them to the synthesis of biologically active natural products. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Here, we describe our synthetic study of nitrogen-containing heterocycles using ring-closing metathesis (RCM), such as chiral bicyclic lactams, azacycloundecenes, axially chiral macrolactams, 1,2-dihydroquinolines and indoles, including the development of silyl-enol ether ene metathesis and selective isomerization of terminal olefin, and its application to the synthesis of the natural products, (Ϫ)-coniceine, (S)-pyrrolam A and angustureine.…”