ChemInform Abstract: Synthesis of 6H‐Dibenzo[b,d]pyran‐6‐ones Using the Inverse Electron Demand Diels—Alder Reaction.

Abstract

In some cases, the dihydro analogues are obtained which can smoothly be converted into the title compounds by treatment with DDQ.

Axially Chiral Cannabinoids: Design, Synthesis, and Cannabinoid Receptor Affinity

“…While 13 has the correct 1,3-diene geometry, the kinetics and thermodynamics of the desired [4+2] cycloaddition are less favorable due to the aromaticity of the coumarin (which must be broken during the Diels-Alder reaction). 40,44,45 Thus, to achieve the desired transformation, reversal of the innate Curtin-Hammett controlled reactivity is necessary. Toward this goal, we envisioned that a transition-metal catalyst could template the diene and dienophile (via intermediate-A (Int-A); Scheme 1C), resulting in an altered kinetic profile and mechanism favoring formation of the coumarin-dearomatized [4+2] product (Figure 2).…”

“…This was an interesting outcome as it resulted in an axially chiral biaryl by a unique method, and the structure is reminiscent of the theoretical "parent" axially chiral cannabidiol (axCBD). Regarding the method, Diels-Alder reaction between dienes and alkynes to yield arenes usually relies on oxidation of the intermediate 1,4-cyclohexadiene 45,55 or elimination of an endocyclic leaving group. 56,57 Thus, this represents a unique strategy for targeting substituted and functionalized arenes.…”

Cascade Lactonization/Benzannulation of Propargylamines with Dimethyl 3-Oxoglutarate for Modular Assembly of Hydroxylated/Arene-Functionalized Benzo[c]chromen-6-ones

“…In 2011, Bodwell and co-workers investigated the reaction between dienes and enamine derived from ketone and pyrrolidine for affording the benzo [c]chromen-6-one bearing an ester group via the domino inverse electron demand Diels− Alder reaction (IEDDA) (Scheme 1a(i)). 10 Later, an improved multicomponent domino reaction, with Knoevenagel condensation, transesterification, enamine formation, IEDDA reaction, 1,2-elimination, and transfer hydrogenation, was further developed (Scheme 1a(ii)). 11 Iaroshenko and Langer disclosed a one pot synthesis pathway by Pd-catalyzed Sonogashira cross-coupling reactions of 4-chloro-2-oxo-2Hchromene-3-carbaldehyde and subsequent cyclocondensation with 1,3-dicarbonyl compounds (Scheme 1a(iii)).…”