The catalytic cyclization/silylation reaction of hindered dienes has been investigated using the relatively unhindered complexes Me2Si (C5H3SiMe3) 2YCH (TMS) 2 and [CpTMS2LnMe] 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 ...