[4+2] Cycloaddition Chemistry of Substituted Furans

Biobased C6-Furans in Organic Synthesis and Industry: Cycloaddition Chemistry as a Key Approach to Aromatic Building Blocks

“…Rather, we focus on bioderived C 6 -furanic building blocks. It has been demonstrated that the reactivity of substituted furans strongly depends on the nature of substituents at the C2 and C5 positions; thus, the reactivity of several bioderivatives with functional groups strongly differs from the commonly accepted behavior of nonfunctionalized furans. − For example, even the appearance of a single −CHO group at the C2 position completely hampers cycloaddition under regular conditions. Controlling the reactivity and achieving high efficiency in the F2B process are the major challenges with paramount importance for the implementation of carbon neutral sustainable technologies in the chemical industry.…”

Enantioselective Iron-Catalyzed Cross-[4+4]-Cycloaddition of 1,3-Dienes Provides Chiral Cyclooctadienes

“…The enantioselective cross-[4+4]-cycloaddition could be successfully extended to branched dienes with heteroaromatic substituents. A 3-furyl-derived diene 2g gave rise to [4+4] product 3ag in 79% yield and 95:5 er with any observed [4+2]-cycloaddition involving its furan moiety . The transformation is scalable as demonstrated by the synthesis of 3db on a 1.2 mmol scale (4-fold increase).…”

Diels–Alder Reactions of Furans with Itaconic Anhydride: Overcoming Unfavorable Thermodynamics

“…This frequently results in only low equilibrium conversion to the [4+2] adduct because of loss of heteroaromaticity in the diene and ring strain in the 7-oxanorbornene product. 11 This is all the more true for 1,1-disubstituted dienophiles analogous to 1 (e.g., methacrolein, 12 methacrylates, 12a–c and methacrylonitrile 12d ), where the equilibrium concentration of product ranges from 7–36% even in the presence of 20-fold excess of furan, at low temperature, and/or under high pressure.…”