ChemInform Abstract: A New Synthesis of 1,7-Dioxaspiro(5.5)undec-4-enes via Metallated Allenol Ethers. A Formal Synthesis of Talaromycins A and B.
Abstract
The α-iodo-ω-siloxyalkanes (I) are coupled with the allenol ether (II) to produce the methoxysiloxyalkylallenes (III).
ChemInform Abstract
The α-iodo-ω-siloxyalkanes (I) are coupled with the allenol ether (II) to produce the methoxysiloxyalkylallenes (III). These compounds react with the trans-substituted oxiranes (IV), yielding the diols (VI) after desilylation. Treatment of (VI) with pyridinium tosylate results in ring-closure, forming the spiro acetals (VII), together with the monocyclic acetals (VIII). The by-products(VIII) are completely converted to (VII) by addition of a catalytic amount of iodine to the reaction mixture. The compounds (VII) are precursors of various natural products, e.g. (VIIa) is hydrated to give the olive-fly pheromone (IX). (VIIb) is transformed into the talaromycins A and B (X).
