A highly versatile
palladium-catalyzed allylation reaction of several
pronucleophiles is reported. The use of propadiene in toluene provides
an atom economic and waste-free access to allylated nucleophiles,
a structural motif with almost unlimited possibilities for further
functionalization. In addition to N-, O-, and S-pronucleophiles, the Pd/BINAP system is
capable of adding a C-pronuceophile to allene. A
plausible mechanism is supported by deuterium labeling experiments.
A general Rh-catalyzed addition reaction of nitrogen containing heterocycles to internal allenes is reported. Starting from racemic internal allenes a dynamic kinetic resolution (DKR) provides N-allylated triazoles and tetrazoles. Simultaneous control of N1/Nx-position selectivity, enantioselectivity and olefin geometry gives access to important building blocks of target-oriented synthesis. The synthetic utility is demonstrated by a gram-scale reaction and a broad substrate scope tolerating multiple functional groups. Deuterium labeling experiments and experiments with enantioenriched allenes as starting material support a plausible reaction mechanism.
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