As an entry to furoquinoline structures of natural origin, the rhodium-mediated dipolar cycloaddition of diazoquinolinediones with alkenes and alkynes has been examined. Because of the unsymmetrical nature of the diazo compounds, both linear and angular furoquinoline products are possible. For the most part, a mixture of regioisomers is generated in moderate to good yields, though in a few cases dominant products are obtained in high yields. The products can be further converted to naturally occurring alkaloids such as isodictamnine. A novel observation in this work is that catalytic quantities of acid enhance the yield and regiochemical control in the cycloaddition.

Based on a general modular synthetic scheme, a variety of chiral bidentate P/P‐, P/S‐, P/N‐, and P/Se‐ligands is accessible in an efficient divergent manner starting from phenol or naphthol derived backbone systems. A library of 20 selected ligands was tested in the Rh‐catalyzed asymmetric hydroboration of styrene to give 1‐phenylethanol in up to 91% ee after oxidative work‐up. It was demonstrated that small variations of the ligand structures lead to pronounced, unpredictable differences in the performance of the in situ generated rhodium complexes. The modular approach should be applicable for the identification and optimization of suitable ligands for other transition metal‐catalyzed transformations with comparably low effort.

The radical cation of tricyclo[4.3.1.01,6]deca-2,4-diene (3) can be generated by electron transfer to 1,4-dicyanobenzene (DCB) in acetonitrile/methanol; the species is captured by regiospecific nucleophilic attack of methanol in the 2- (and 5-) position. On the other hand, the reaction shows little stereochemical preference. The resulting allylic radical reacts by aromatic substitution on the radical anion of DCB, the 3-position serving as the principal site of coupling. Remarkably, the cyclopropane function of 3 • + is not a target of nucleophilic attack, even though the secondary cyclopropane carbon has spin and charge density. The observed reaction is compatible with a theoretical model proposed by Shaik and Pross, which correlates radical cation reactivity with the spin density of the corresponding triplet state. The capture of 3 • + occurs in the position where both SOMO and LUMO have significant orbital coefficients.

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