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[摘要]：A concise route to macrolactone 38, an advanced intermediate of the Nicolaou/Chen synthesis of palmerolide A, is described. Key steps in our synthesis include a Noyori transfer hydrogenation of all alkynone, chain extension via Claisen rearrangement, and an ADH reaction on an enyne. After reduction Of the triple bond, a selective silylation served to differentiate the hydroxy groups of the diol, which allowed for the preparation of aldehyde 30 containing already the carbamate function. A HWE reaction produced the substrate for an intramolecular Heck Coupling. In contrast to the Stille cyclization, the Heck cyclization produced only the desired 14E, 16E-diene. Elaboration of the C-19 side chain led to the key lactone 38. |
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