Easy aryl reductions The Birch reduction has been widely used for more than half a century to achieve partial reduction of aryl rings by alkali metals at just two diametrically opposed carbon sites. However, the conditions require condensation of caustic gaseous ammonia. A variation developed soon afterward by Benkeser used safer liquid ethylene diamine but was prone to overreduction. By diluting ethylene diamine in tetrahydrofuran solvent, Burrows et al . now obtain selectivities comparable to Birch conditions but without the need for condensed ammonia. —JSY

MPC1001 is a potent anticancer natural product that contains a violaceic acid moiety. Herein we report the total synthesis of the natural product violaceic acid and its derivative. In this approach, a triazene-directed Ullman coupling proved to be highly effective. We converted the triazene to a hydroxy group by means of a palladium-catalyzed reaction. Treatment of the triazene with trifluoroacetic acid generated an arenediazonium ion that produced an aryl radical, leading to the protodediazoniation and a tricyclic product.

FR901464 and thailanstatins are potent cytotoxic natural products that share an amine-containing tetrahydropyran ring. We previously reported the synthesis of the tetrahydropyran component. Here, we changed the protecting group for the amine from Boc to tosyl, improving yields and the time economy. A highlight of the revised synthetic scheme is the use of lithium, t-butanol, and ethylenediamine in THF (nontraditional Birch reduction conditions) for the N-detosylation.