Concise synthesis of cyclic ethers via the palladium-catalyzed coupling of ketene acetal triflates and a zinc homoenolate. Synthesis of the DE and GH ring segments of gambierol
Concise syntheses: of the DE and GH ring segments of gambierol (1) were achieved by the palladium-catalyzed coupling of ketene acetal triflates and a zinc homoenolate, followed by the hydroboration of the resulting cyclic enol ethers and subsequent lactonization. (C) 2001 Elsevier Science Ltd. All rights reserved.
Concise Synthesis of Cyclic Ethers via the Palladium-Catalyzed Coupling of Ketene Acetal Triflates and Organozinc Reagents. Application to the Iterative Synthesis of Polycyclic Ethers
The reaction of the keteneacetal triflates 9a-e and a zinc homoenolate 10 in the presence of a catalytic amount of Pd(PPh(3))(4) gave the enol ethers 11a-e in good yields. The products were converted to the corresponding cyclic ethers 14a and 14b by hydroboration and lactonization. The present methodology allowed us to synthesize the DE and GH ring segment of gambierol in a concise manner. Iterative