The intramolecular hydroamination of hindered alkenes has been developed as a versatile route to heterocyclic systems. The current process utilizes the unhindered catalyst system [CpTMS 2LnMe]2 (Ln = Sm, Nd) to effect the cyclization of hindered amino olefins, providing products containing quaternary centers. The process tolerates a wide variety of substitution patterns, allowing the construction of monocyclic as well as fused and bridged bicyclic heterocycles. Two experimental procedures were employed in this study:  one without solvent, minimizing waste streams, the other in deuterated solvents, allowing NMR monitoring of the reaction. The yield of each reaction was high, with NMR analysis of the reactions in progress showing clean conversion from starting material to a single product in most cases.

The regioselectivity of monosubstituted alkene hydrosilylation catalyzed by organolanthanide and group 3 organometallic complexes has been studied as a function of catalyst structure. A wide variety of catalyst variations were shown to be compatible with the hydrosilylation process. Several novel complexes were synthesized to widen the scope of this investigation. The results show complexes containing larger lanthanide metal ions and reduced substitution on the cyclopentadienyl ligands produce increased yields of the secondary silane product. Several complexes were identified that are highly selective for primary silane generation.Supporting Information Available: NMR spectra for compounds without reported elemental analyses as well as details of the X-ray stucture determination of 6 and 7 (27 pages). Ordering information is given on any current masthead page.

The catalytic cyclization/silylation reaction of hindered dienes has been investigated using the relatively unhindered complexes Me 2 Si(C 5 H 3 SiMe 3 ) 2 YCH(TMS) 2 and [Cp TMS 2 LnMe] 2 (Ln ) Y, Lu). A wide variety of dienes and trienes bearing a number of functional groups were cyclized, affording silanes containing quaternary centers in a diastereoselective fashion and in good yield. The products can be oxidized using one of several different protocols, yielding alcohols for further functionalization.

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A diastereoselective, lanthanocene-catalyzed, intramolecular hydroamination reaction was applied to the preparation of 2,6-disubstituted piperidines. Various metal/ligand arrays in the catalysts were examined using a model substrate to allow optimization of the diastereoselectivity. It was determined that the relationship between metal size and ligand bulk plays an integral role in the transformation. The complex Cp2NdCH(TMS)2 converted 2-substituted 8-nonen-4-amines to 2,6-disubsituted piperidines with greater than 100:1 selectivity for the formation of the cis isomer. A short synthesis of pinidinol, an alkaloid isolated from various pine and spruce species, was then carried out to exploit this stereoselective reaction.