Tunable Dimerization and Trimerization of β‐Alkynyl Ketones via Silver Catalysis for Accessing Spiro and Dispiro Compounds Containing 1H‐Isochromene

Abstract

New silver‐catalyzed tunable dimerization and trimerization reactions of β‐alkynyl ketones have been established, enabling multiple C−C bond‐forming events to selectively access skeletally diverse spiroisochromenes with generally good yields. The silver‐enabled bicycloaddition of β‐alkynyl ketones with water offered hydroxylated spiroisochromenes. Without water, spiroisochromenes with a methylene moiety were obtained through catalytic 6‐endo‐dig oxo‐cyclization/[4+2] cycloaddition cascades by using pyridine as additive whereas employment of 1,1′‐binaphthyl‐2,2′‐diyl hydrogen phosphate (BiNPO4H) as a Brønsted acid catalyst rendered the unprecedented dispiro trimerization products through double C(sp3)–H functionalization.magnified image

Dual Palladium/Scandium Catalysis toward Rotationally Hindered C3‐Naphthylated Indoles from β‐Alkynyl Ketones and o‐Alkynyl Anilines

“…On the basis of the aforementioned experimental results and previous reports on the catalytic cyclization of β‐alkynyl ketones, [ 28‐35,39‐43,45,46 ] a reasonable reaction pathway is proposed in Scheme 5. Initially, interaction between o ‐alkynyl aniline 2 and the Pd catalyst leads to the in‐situ formation of the indole intermediate C through aza‐cyclization and protodemetallation.…”

“…toward spiro‐substituted 1 H ‐isochromenes by intercepting in situ generated benzopyrylium intermediates. [ 39‐42 ] To continue our efforts on this project, we conceived that under a set of catalytic conditions, the [4 + 2] cycloaddition of β‐alkynyl ketones 1 as benzopyrylium precursors with o ‐alkynyl anilines 2 as electron‐ rich alkynes would occur, followed by ring‐opening of the benzopyrylium ring and subsequent dehydration to offer tetracyclic benzo[ i ]phenanthridines 4 . Surprisingly, the reaction proceeded in a completely unexpected direction, furnishing a wide range of unprecedented rotationally hindered C3‐naphthylated indoles 3 with satisfactory control of chemo and regioselectivities achieved through a palladium/scandium co‐catalyzed annulation cascade (Scheme 1d).…”

Preparation and Characterization of Hollow MgO/SiO2 Nanocomposites and Using as Reusable Catalyst for Synthesis of 1 H-isochromenes

“…Some natural compounds that include the isochromene were accidin separated of the orchids, Dendrobium amoenum also Coelogyne accida and also the numerous of compounds which separated from Cannabis sativa, can be observed as isochromenederivatives (Papadakis et al, 1983). Three derivatives of Ulmusdavidiana which comes from Korea are utilized in orientalmedicines for the usage of edema, in ammations, and stomach cancer.The enormousvalue of these compounds have inspired much effort to advance a vast number of in uential and dependable procedures for their syntheses (Wang et al, 2017). Outdated 1H-isochromene synthesized with dimerization of benzopyrylium salts in acid conditional (Verin et al, 1991).…”

Preparation and Characterization of Hollow MgO/SiO2 Nanocomposites and using as Reusable Catalyst for Synthesis of 1H-Isochromenes

“…Some natural compounds that include the isochromene were accidin separated of the orchids, Dendrobium amoenum also Coelogyne accida and also the numerous of compounds which separated from Cannabis sativa, can be observed as isochromenederivatives (Papadakis et al, 1983). Three derivatives of Ulmusdavidiana which comes from Korea are utilized in orientalmedicines for the usage of edema, in ammations, and stomach cancer.The enormousvalue of these compounds have inspired much effort to advance a vast number of in uential and dependable procedures for their syntheses (Wang et al, 2017). Outdated 1H-isochromene synthesized with dimerization of benzopyrylium salts in acid conditional (Verin et al, 1991).…”