Diels–Alder dimerization of Morita–Baylis–Hillman acetates catalyzed by organocatalysts

Phosphine-Promoted Tandem Intermolecular Diels-Alder Reactions with Pentadienyl 4-Nitrobenzoate as a Diene Precursor

A phosphine-promoted tandem Diels-Alder reaction using pentadienyl 4-nitrobenzoate (α-vinyl MBH adduct) as a diene precursor with 3-olefinic oxindoles or CF3-activated ketones as dienophiles has been developed. The reaction proceeds through the formation of a pentadienyl phosphonium intermediate via SN2'' addition, which acts as both a D-A diene and a precursor for the exomethylene moiety. This method offers a metal-free and step-efficient approach for synthesizing exomethylene-bearing spirooxindoles and dihydropyrans, which are privileged structures found in natural products.

Chemoselective tandem SN2'/SN2''/inter- or intramolecular Diels-Alder reaction of γ-vinyl MBH carbonates with phenols and o-hydroxychalcones

An unprecedented consecutive S_N2'/S_N2'' addition of phenol to γ-vinyl MBH carbonate forms a reactive diene intermediate, followed by a dimerization/elimination process to give functionalized exocyclohexenes with excellent chemoselectivity. When using o-hydroxychalcones as pronucleophiles, an S_N2'/S_N2''/intramolecular Diels-Alder reaction sequence occurs, selectively producing a series of pharmaceutically intriguing tricyclic chromane derivatives with good diastereoselectivity. The good nucleophilicity and fair nucleofugicity exhibited by phenoxy anion play a pivotal role in the S_N2'' addition step.

Total Synthesis and Prediction of Ulodione Natural Products Guided by DFT Calculations**

A biomimetic synthetic strategy has resulted in a two‐step total synthesis of (±)‐ulodione A and the prediction of two potential natural products, (±)‐ulodiones C and D. This work was guided by computational investigations into the selectivity of a proposed biosynthetic Diels–Alder dimerization, which was then utilized in the chemical synthesis. This work highlights how biosynthetic considerations can both guide the design of efficient synthetic strategies and lead to the anticipation of new natural products.

Recent advances in the annulation of Morita–Baylis–Hillman adducts

In this review, we summarize some of the most recent advances in the construction of cyclic compounds from the annulation of Morita–Baylis–Hillman (MBH) adducts, which have demonstrated their importance by possessing diverse functional groups.