| Abstract
| - The reaction of open-chain or cyclic α-diketones with specific ω-alkenyl organometallics leads readilyunder the proper conditions to 1,2-diols bonded to terminal olefinic chains. With 1-phenyl-1,2-propanedione, biacetyl, and cyclohexane-1,2-dione, allylindation in aqueous THF proceeds readilyat both adjacent carbonyls. For cyclododecane-1,2-dione, recourse must be made to allylmagnesiumbromide for completing the second-stage condensation. Grignard reagents have also served well asreactants for biacetyl monoadducts. In contrast, monoallylated camphorquinone is reluctant to coupleto Grignard reagents and reacts only when Barbier-type alkyllithium reactions are applied. Thering closing metatheses of these products have been examined. Where six-membered ring formationoperates, cyclization can be performed directly on diols. When larger rings are involved, the diolswill react only if structural preorganization capable of facilitating mutual approach of the two doublebonds is at play. For this purpose, the prior conversion to a cyclic carbonate holds considerableutility. In the latter setting, saponification must precede the diol cleavage step which has beenperformed with lead tetraacetate. The latter reagent also exhibits the very beneficial effect offacilitating removal of ruthenium and phosphorus byproducts generated during the metathesisstep. This chemistry conveniently lends itself to the controlled intercalation of multiple methylenegroups between the carbonyl carbons of readily available α-diketones to deliver linear or cyclicproducts.
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