Trisannulation reagent

Allyl aryl ethers are used for allylation under basic conditionsfh], but they can be cleaved under neutral conditions. Formation of the five-membered ring compound 284 based on the cyclization of 283 has been applied to the syntheses of methyl jasmonate (285)[15], and sarkomycin[169]. The trisannulation reagent 286 for steroid synthesis undergoes Pd-catalyzed cyclization and aldol condensation to afford CD rings 287 of steroids with a functionalized 18-methyl group 170]. The 3-vinylcyclopentanonecarboxylate 289, formed from 288, is useful for the synthesis of 18-hydroxyestrone (290)[I7I]. 

The trisannulation reagent 7-acetoxy-l,l l-dodecadien-3-one (134) is derived from the bisannulation reagent 124 in four steps. This reagent is a synthetic equivalent of l-dodecene-3,7,11-trione, and the two ketone groups of the trione are masked as an acetoxy and a terminal alkene. The synthesis of optically active D-homo-19-norandrosta-4-en-3-one (135) by the trisannulation reaction... 

Tsuji has also prepared the trisannulation reagent 75 from dienone 62 as indicate and utiliz it in a synthesis of ( )-D-homoandrost4-ene-3,17a-dione. ... 

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