Prophylactic beta-adrenergic blockade is effective in slowing the rate of aortic dilatation and reducing the development of aortic complications in some patients with Marfan's syndrome.

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The synthesis of ß, -unsaturated ketones from carboxylic acid anhydrides, zinc chloride, and a variety of cyclic and acyclic olefins is found to be effective only for simple anhydrides and olefins. The conversions of 1 -methylcyclohexene (3) to 6-acetyl-1 -methylcyclohexene (4) and of methylenecyclohexane (9) to 1 -cyclohexenylacetone (10) are illustrative of the 22 cases included. The observation of a product isotope effect in the absence of a corresponding kinetic isotope effect in the series methylenecyclohexane, methylenecyclohexane-2,2-íf2 {9-di), and methylenecyclohexane-2,2,6,(5-rf4 (9-dj) is compelling evidence for a reaction intermediate. Substituent effects are taken to support a carbocationic species and the regiospecificity of the reaction is consistent with intramolecular proton transfer in that intermediate. The value of the series 9, 9-di, and 9-dn for distinguishing concerted and stepwise mechanisms for formal ene reactions is noted.