Aliphatic allylic acetates were reduced to alkenes with hexacarbonylmolybdenum(0) in refluxing dioxane under nitrogen atmosphere. These reactions were accelerated by the addition of H2O. 1-Aryl- or 3-arylallyl acetates caused deacetoxylative allylic homocoupling under the same conditions.
Step saver: Carbonyl groups with lower reactivities can be transformed in the presence of more reactive ones by treatment with PPh3 (or PEt3) and TMSOTf prior to the reaction (see scheme; TMS=trimethylsilyl, Tf=trifluoromethanesulfonyl). This methodology can be applied to reduction and alkylation reactions, and enabled the short asymmetric totalsynthesis of (+)‐centrolobine with the highest overall
Pd(O)-catalyzed electroreductive cleavage of allylic acetates yielding alkenes and/or allyltrimethylsilanes is described. Deprotection of allyl esters can be performed in the same electrolysis system.
Trimethylallylsilane reacts with monothioacetals in the presence of tin (IV) chloride, titaniumtetrachloride, or boron trifluoride–diethyl ether to give the homoallyl ethers and homoallyl sulphides.