ChemInform Abstract: A Comprehensive Study of [2 + 2] Cycloadditions and Ene Reactions of Alkynyl Chromium and Tungsten Carbene Complexes with Enol Ethers and Ketene Acetals and of the Stereochemistry of the Electrocyclic Ring Opening of Cyclobutenyl Carbene Complexes.

✍ Scribed by William D. Wulff; Katherine L. Faron; Jing Su; James P. Springer; Arnold L. Rheingold

• Publisher: John Wiley and Sons
• Year: 2010
• Weight: 39 KB
• Volume: 30
• Category: Article
• ISSN: 0931-7597
• DOI: 10.1002/chin.199922075

✦ Synopsis

A Comprehensive Study of [2 + 2] Cycloadditions and Ene Reactions of Alkynyl Chromium and Tungsten Carbene Complexes with Enol Ethers and Ketene Acetals and of the Stereochemistry of the Electrocyclic Ring Opening of Cyclobutenyl Carbene Complexes.

-Cyclobutenyl esters and their ring opened isomers such as (III), (V), (VI), (X), and (XI) are synthesized by reaction of alkynyl carbene complexes with enol ethers. The cyclobutenyl carbene complex (XIII) obtained from the cycloadditions with the Z-and E-isomers of propenylether (XII) undergoes stereoselective electrocyclic ring-opening to give only E,Z-complex (XV) which results from the conrotatory ring-opening. Furthermore, the metal in the complexes can be oxidatively removed, cf. (VII). The cyclobutenyl carbene complexes and the butadienyl carbene complexes are also of synthetic value as exemplified by Diels-Alder, cf. (XVII) → (XIX), and cyclohexadienone annulation reactions. -(WULFF, WILLIAM D.; FARON, KATHERINE L.;