Valsartan 1, one of the most important agents used in antihypertensive therapy today, was synthesized starting from L-valin methyl ester hydrochloride 2 through four steps in an overall yield of 60%. The key step involves the palladium-catalyzed Suzuki coupling. This method overcomes many of the drawbacks associated with the previously reported syntheses and is more suitable for industrial production.
Ligudentatin A 1, a new phenolic norsesquiterpenes, was first synthesized starting from （＋）-perillaldehyde 3 through five steps, successively, in an overall yield of 20.8%. The key steps were the Diels-Alder reaction and aromatization of enone to phenol.
We reported that a benzyl-type binaphthyl disulfone could be conveniently converted into dibenzophenanthrene. Thus, racemic 1 was treated with lithium diisopropylamide (LDA) afforded dl-dibenzophenanthrene in a moderate yield, together with an unknown benzensulfonyl-substituted derivative 2. The structures were confirmed by MS, 1H, 13C NMR and elemental analysis. The reaction might involve the initial intramolecular nucleophilic substitution to produce an intermediate 3, followed by elimination of benzenesulfinic acid to form dibenzophenanthrene.
