Nickel-Catalyzed Cyclization of 1,3-Diene with a Tethered Carbonyl Group and Its Application to Synthesis of Natural Products.
- 1 January 2001
- journal article
- Published by The Society of Synthetic Organic Chemistry, Japan in Journal of Synthetic Organic Chemistry, Japan
- Vol. 59 (6) , 576-588
- https://doi.org/10.5059/yukigoseikyokaishi.59.576
Abstract
A nickel-promoted intramolecular cyclization of 1, 3-diene with the tethered carbonyl group was developed using the catalyst generated by reduction of Ni(acac)2 with DIBAL-H in the presence of PPh3. The reaction course of this cyclization can be accounted for by two possible mechanisms. In one mechanism, a nickel hydride complex plays a key role and the cyclization proceeds via πallylnickel intermediate. In the other mechanism, a zerovalent nickel complex is the active species and the cyclization proceeds via the nickelacycle intermediate. These mechanistic considerations led to find two nickel (0) -catalyzed cyclizations of 1, 3-diene and the tethered aldehyde, in which the five- to seven-membered ring products were produced in a regio- and stereoselective manner via, π-allylnickel intermediate (Type I cyclization) or via transmetalation process of nickelacycle intermediate with iBu2Al-acac (Type II cyclization). We also succeeded in applying these cyclizations to the syntheses of (-) -elaeokanine C and (+)-prostaglandin F2α, and in demonstrating the catalytic asymmetric cyclization using Type I cyclization.Keywords
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