A [2 + 2] Photocycloaddition-Fragmentation Approach toward the Carbon Skeleton of cis-Fused Lycorine-type Alkaloids.

Starting from isoquinolones, the cis-selective annulation of six-membered rings was possible employing cyclobutenes as olefin components in a [2 + 2] photocycloaddition-fragmentation approach (nine examples, 54-80% yield). The developed sequence enables a conceptually new entry to cis-fused lycorine-type alkaloids of the Amaryllidaceae family with the complete carbon skeleton being successfully assembled. A subsequent von Braun-type reaction emphasized the biological relation between lycorine- and homolycorine-type alkaloids providing a synthetic tool to access this class of natural products.

Borane-catalyzed room-temperature hydrosilylation of alkenes/alkynes on silicon nanocrystal surfaces.

Room-temperature borane-catalyzed functionalization of hydride-terminated silicon nanocrystals (H-SiNCs) with alkenes/alkynes is reported. This new methodology affords formation of alkyl and alkynyl surface monolayers of varied chain lengths (i.e., C5-C12). The present study also indicates alkynes react more readily with H-SiNC surfaces than equivalent alkenes. Unlike other toxic transition-metal catalysts, borane or related byproducts can be readily removed from the functionalized SiNCs. The new method affords stable luminescent alkyl/alkenyl-functionalized SiNCs.

Bidentate cycloimidate palladium complexes with aliphatic and aromatic anagostic bonds.

Palladium(II) complexes of bidentate cycloimidate ligand systems with a triarylmethyl moiety exhibit exceptional downfield shifts in proton NMR spectra due to rare anagostic interactions.