Synergistic Catalysis: Metal/Proton‐Catalyzed Cyclization of Alkynones Toward Bicyclo[3.n.1]alkanones

Abstract

A highly efficient and practical synergistically metal/proton-catalyzed Conia-ene reaction for the synthesis of bicyclo[3.n.1]alkanones has been developed. This synergistic catalysis was successfully utilized in modifying natural compounds such as methyl dihydrojasmonate, α,β-thujone, and 5α-cholestan-3-one. Furthermore, the bridged carbonyl group of bicyclo[3.2.1]alkanones could be easily attacked by nucleophiles to give the ring-opened cycloheptenone products or bicyclo[4.2.1]amide in excellent yields. These reactions provide rapid access to a diverse range of cyclic structures from simple starting materials or naturally occurring compounds.

Carbonyl-assisted reverse regioselective cascade annulation of 2-acetylenic ketones triggered by Ru-catalyzed C–H activation

“…To further demonstrate the synthetic utility of this methodology, the cascade annulation reaction was then employed on the 2-acetylenic ketone 4 derived from the steroid 5α-cholestan-3-one ( Scheme 4 ). Initially, 5α-cholestan-3-one was converted to alkyne 4 using the procedure from the literature in 3 steps, 17 which was further subjected to the annulation reaction with 1a , 1ab and 1ai under standard reaction conditions to afford the desired polycyclic products 5a , 5b and 5c , respectively, in 58–67% yields.…”

Synergistic Diazo‐OH Insertion/Conia‐Ene Cascade Catalysis for the Stereoselective Synthesis of γ‐Butyrolactones and Tetrahydrofurans

“…Among them, synergistic cascade catalysis transformations are of particular importance as they allow for price efficiency in terms of reagents, solvents, and waste management as well as in time and effort . In synergistic catalysis, at least two different catalysts act on two different reactive sites simultaneously to lower the energy barrier for bond formation (Scheme ) . Therefore, synergistic approaches not only improve the efficiency of existing reactions but also enable new chemical transformations.…”

Enantioselective Organocatalytic Desymmetrization of Cyclopentene-1,3-diones through Formal C(sp2)–H Amidation

“…Amides 1a – w were prepared following literature procedures . Cyclopantene-1,3-diones 2a – l were prepared following literature procedures. , Norbornenoquinone 2m was prepared according to literature procedures …”