Triplex-catalyzed diels-alder and [2+2] cycloaddition reactions of enol ethers and ketene acetals

✍ Scribed by Nihat Akbulut; Gary B. Schuster

• Publisher: Elsevier Science
• Year: 1988
• Tongue: French
• Weight: 229 KB
• Volume: 29
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)80697-8

✦ Synopsis

Summarv:

Irradiation of benzene solutions containing a cyanoarene sensitizer, 1,3-cyclohexadiene, and a trimethylsilyl enol ether or ketene acetal leads to intermolecular [4+2] and [2+2] cycloaddition products.

The Diels-Alder reaction is widely regarded as among the most useful and general of the known methods for preparation of compounds containing six-membered rings. This thermal cycloaddition normally proceeds rapidly with predictable outcome when an electron-rich diene combines with an electron-poor dienophile. In contrast, Diels-Alder cycloadditions often fail when both the diene and dienophile are electron-rich compounds and the desired reaction is too sluggish to overcome competing processes. Recognition of this problem has resulted in attempts to find procedures that can accelerate the cycloaddition'.