Quassinoids are highly oxygenated triterpenes, which were isolated as bitter principles from the plants of Simaroubaceae family. Their synthesis has attracted much attention because of the wide spectrum of their biological properties. The most prevalent quassinoids have C-20 picrasane skeleton, some known as bruceolides as they were isolated from the genus Brucea, which showed marked antileukemic and antimalarial activities.

The rhodium-catalyzed addition of arylboronic acids to N-Boc imines generated in situ from stable and easily prepared alpha-carbamoyl sulfones has been developed. High enantioselectivities are observed for additions of arylboronic acids with a variety of steric and electronic properties.

Polyphenylalkane derivatives Q 0720Catalytic Enantioselective Addition of Arylboronic Acids to N-Boc Imines Generated in situ. -The reaction is applied to a range of functionalized arylboronic acids and N-Boc imines including electron-poor and electron-rich as well as ortho-substituted derivatives. -(NAKAGAWA, H.; RECH, J. C.; SINDELAR, R. W.; ELLMAN*, J. A.; Org. Lett. 9 (2007) 25, 5155-5157; Dep. Chem., Univ. Calif., Berkeley, CA 94720, USA; Eng.) -R. Steudel 18-085