The bisphosphine monoxide (R,R)-BozPhos enables enantioselective C−H functionalization of cyclopropanes in a palladium-catalyzed cyclization. The synthesis of a broad spectrum of dihydroisoquinolones and dihydroquinolones in good yields and high enantiomeric excess was achieved through the use of this hemilabile ligand. Furthermore, the isolation of an intermediary palladium(II)-BozPhos complex after oxidative addition was successful and a second complex provided further insight into bond length and angles through a crystal structure.

The carbon skeleton of the Stemona alkaloids stemokerrin and cochinchistemonine was assembled from three building blocks (a piperidine, a furan, and a tetronate). Key steps linking the fragments included a Stille cross-coupling (piperidine/furan) and an aldol type addition of a tetronate. The furan served as a latent 1,4-difunctional compound which was converted to a γ-ketolactone by a type II photooxygenation. Attempts to construct the C12-C13 double bond of stemokerrin by a late stage oxidation or by an elimination remained unsuccessful. The non-natural products dihydrostemokerrin and furostemokerrin were obtained instead.

Starting from a readily available, enantiomerically pure 2,6disubstituted piperidine the synthesis of pyrido[1,2-a]azepines was accomplished. Key reactions for the ring closure were a photochemically induced acyl radical addition or a SmI 2 -promoted ketyl radical addition to an α,β-unsaturated ester. En route to the cyclization precursor an epoxidiation/ring opening sequence led to an undesired oxazolidinone which turned out to be useful for the configuration assignment. The compound was successfully converted into (+)-methyl dihydropalustramate.

An operationally simple protocol for the direct chlorination of 1,3-dicarbonyls (and related compounds such as α-cyano ketones) is described. The procedure relies on mild conditions using IBX-SO 3 K as the stoichiometric oxidizing agent and the ubiquitous sodium chloride. The presence of a phase-transfer catalyst is supportive to obtain good yields in a THF-water mixture.