Nickel-promoted steroselective cyclization of 1,3-diene and carbonyl group. Effect of 1,3-diene as a ligand
- Hokkaido Univ., Sapporo (Japan)
The authors have recently reported a novel stereoselective cyclization of 1,3-diene and the carbonyl group in a chain, in which the hydride nickel complex 4 plays an important role. By use of Et{sub 3}SiH as a hydride source, the catalytic cycle was established to produce 8c, 9c, or 10 as the sole product from the corresponding 1,3-diene. Here, the authors want to report that the compound having 1,3-diene affects the stereochemistry of the product in this cyclization. The reaction of 1 with 4 (100 mol %) afforded the endo-olefin 8b in 69% yield. On the other hand, the exo-olefin 8a was produced predominantly, when 1,3-cyclohexadiene (CHD) (150 mol %) was added to the reaction mixture. While the cyclization of 2 using 4 (100 mol %) in the absence of CHD afforded a mixture of 9a and 9b in 82% yield, the exo-olefin 9a was obtained in preference to 9b in the presence of CHD. Although the reaction mechanism has not been clear yet, the authors speculate that the hydride nickel complex 11, coordinated by CHD, serves to produce the compound having exo-olefin preferentially. Further studies are under investigation.
- OSTI ID:
- 250134
- Report Number(s):
- CONF-9508100--
- Country of Publication:
- United States
- Language:
- English
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