Stereoselective synthesis of the C(1)-C(13) segment of dolabelide B.

The efficient construction of the C(1)-C(13) segment of dolabelide B is described. A key element of the synthesis entails BITIP catalyzed asymmetric methallylation to establish the C(7) stereocenter, which was then used to direct the stereoselective installation of the C(9) and C(11) centers through Evans reduction and 1,5-anti aldol condensation, respectively.

Inhibition of chemically-induced neoplastic transformation by a novel tetrasodium diphosphate astaxanthin derivative.

Carotenoids have been implicated in numerous epidemiological studies as being protective against cancer at many sites, and their chemopreventive properties have been confirmed in laboratory studies. Astaxanthin (AST), primarily a carotenoid of marine origin, responsible for the pink coloration of salmon, shrimp and lobster, has received relatively little attention. As with other carotenoids, its highly lipophilic properties complicate delivery to model systems.

Enantio- and diastereoselective additions to aldehydes using the bifunctional reagent 2-(chloromethyl)-3-(tributylstannyl)propene: application to a synthesis of the C16-C27 segment of bryostatin 1.

[reaction: see text] Reactions of the bifunctional allylstannane 2-(chloromethyl)-3-(tributylstannyl)propene with aldehydes have been examined. These generally occur in high yields using Lewis acid promoters and the products can be isolated and purified without incident. Good yields and high enantioselectivities are also realized in catalytic asymmetric allylations (CAA reactions) using the previously described BITIP catalyst system.