Synthesis of a Bicyclo[2.2.1]heptane Skeleton with Two Oxy-Functionalized Bridgehead Carbons via the Diels–Alder Reaction

Abstract

We describe a synthetic method for a bicyclo[2.2.1]­heptane skeleton with two oxy-functionalized bridgehead carbons. This method involves an intermolecular Diels–Alder reaction using 5,5-disubstituted 1,4-bis­(silyloxy)-1,3-cyclopentadienes, the diene structure of which has never been synthesized. Furthermore, the intramolecular Diels–Alder reaction using a diene bearing a dienophile moiety at the C-5 position can provide a tricyclic carbon framework that includes the bicyclo[2.2.1]­heptane skeleton. The novel bicyclo[2.2.1]­heptane derivatives could be utilized as versatile building blocks for organic synthetic chemistry.

Total Synthesis of (+)-Coriamyrtin via a Desymmetrizing Strategy Involving a 1,3-Cyclopentanedione Moiety

“…Asymmetric synthesis of 17 was performed using a modified version of our reported synthetic method. 16 In brief, treatment of 2-methyl-1,3-cyclopentanedione (18) with acrolein diethyl acetal in water at 40 °C induced the in situ generation of acrolein, followed by the Michael addition of 18 to acrolein to afford aldehyde 19. Although the Kigoshi group has reported a similar reaction in the presence of acetic acid, 17 we demonstrated that this reaction does not require an acid catalyst because 18 acts as a Brønsted acid.…”

“…First, we synthesized a precursor for the intramolecular aldol reaction (Scheme ). Asymmetric synthesis of 17 was performed using a modified version of our reported synthetic method . In brief, treatment of 2-methyl-1,3-cyclopentanedione ( 18 ) with acrolein diethyl acetal in water at 40 °C induced the in situ generation of acrolein, followed by the Michael addition of 18 to acrolein to afford aldehyde 19 .…”

Synthesis of 2-Alkyl-2-(2-furanyl)-1,3-cyclopentanediones

“…5 Our group recently reported that 1,4-bis(silyloxy)cyclopentadiene 3 derived from 1,3-cyclopentanedione 4 induces the intramolecular Diels-Alder reaction to afford the tricyclic compound 5 (Scheme 1b). 6 This reaction further shows the utility of 2,2-disubstituted 1,3-cyclopentanediones in synthetic organic chemistry.…”