Cyclo and spirozirconation: Synthesis of new phospholane-boranes and polyphosphine-boranes

The diallylic phosphine-borane Ph(BH3)P(allyl)(2) 6, reacts with the zircon ocene 'Cp2Zr' and gives the bicyclocomplex intermediate 7, characterized by H-1 and P-31 NMR. The electrophilic addition of H+, Br-2, PhPCl2(BH3), Ph2 PCl(BH3) leads to the corresponding stabilized phospholanes 8, 9, 11 and bi cyclophospholane 10, whereas Ph2P(BH3)Li on 9 gives the boro(phospholane-di phosphine) 12. Under the same conditions, the tetraallylsilane (or germane) 13a-b leads to the spirometallacyclopentane 14a-b intermediates. After rea ction with Br-2, Ph2PLi(BH3) and PhPCl2(BH3), the racemic spirannic tetraph osphines 16a-b and the protected spirannic diphosphine 17b are obtained wit h a remarkable selectivity. Decomplexation reaction by Et2NH gives correspo nding free phosphines 3'-17'. (C) 1999 Published by Elsevier Science Ltd. A ll rights reserved.