Deallylation oxidative addition

In dioxane, when X = O or RN, the reaction proceeds smoothly. However, when a methyl group is introduced into the olefmic moiety, the reaction is suppressed. On the other hand, in DMAC the introduction of a methyl group to the olefmic moiety does not affect the catalytic activity, though when X = O or RN, a deallylation reaction proceeds to disturb the cyclization reaction. In DMAC, oxidative addition of the allyl-X group to the ruthenium active species would occur, most likely due to the coordination of a more electron-donating amide solvent. Thus, the two reports are mutually supportive. 

This year has seen several approaches to the core of the zaragozic acids/squalestatins from carbohydrate starting materials. D-Mannose was converted to the glycal 117, elaborated to precursor 118 by a-selective dioxirane oxidation and Cl epoxide ring opening by allyl alcohol, deallylation, oxidation and Grignard addition. Desilylation of 118 with concomitant intramolecular acetalation afforded the core analogue 119 (Schone 30). ... 

Kondo and Mitsudo are the pioneers of transition-metal-catalyzed retro-allylation [7]. They described this phenomenon as deallylation and fi-allyl elimination . Ruthenium-catalyzed reaction of tertiary homoallylic alcohols proceeds in the presence of allyl acetate under an atmosphere of carbon monoxide in tetrahydro-furan (THF) at a relatively high temperature of 180 C to afford the corresponding ketones (Scheme 5.3). Although the exact roles of allyl acetate and carbon monoxide are not clear, they propose a mechanism involving oxidative addition of the... 

In 2008, Nicolaou andLi reported a synthesis of diversonol (932) (Scheme 13.14) (635). The synthesis involved the nucleophilic addition of a lithiated cyclohexene species derived from bromide 938 with the allyl-protected aldehyde 939, followed by oxidation, desilylation, deallylation, and spontaneous xanthone-ring closure of the intermediate phenol (not shown). As in the Brdse synthesis, the enol moiety is oxidized and the C-ring ketone reduced with NaBH4 to generate diversonol (932), which was obtained in eight steps from cyclohexenone 937. 

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