METALATED BICYCLO[3.2.2]NONA-2,6,8-TRIENES, THEIR REARRANGEMENT TO BARBARALANES, AND A SHORT SYNTHESIS OF THE BICYCLO[3.2.2]NONA-2,6,8-TRIEN-4-YL ANION Academic Article uri icon

abstract

  • Five different anions are formed when bicyclo[3.2.2]nona2,6,8triene (1a) is deprotonated: the 6 and 7yl anions when using tBuLi/TMEDA, the 4,6 and 4,7diyl dianions when using nBuLi/tBuOK, and the 4yl anion (1) after quenching the dianions with THF. Reaction of the anions with Me3SnCl gives the 6, 7, and 4monostannylated bicyclo[3.2.2]nona2,6,8trienes 1b, 1c, and 1d as well as the exo4,7, endo4,6, and endo4,7distannylated bicyclo[3.2.2]nona2,6,8trienes 1e, 1f, and 1g, respectively. Reaction of 1 with Me3SiCl and Me3PbCl leads to the corresponding 4silyl derivative 1h and its plumbyl analogue 1i. Inversely, cleavage of 1d with MeLi allows to generate 1 under particularly mild conditions. The metallation of tricyclo[3.2.2.02,4]nona6,8diene (3a), which was tested for an alternative route to 1, gives two stannyl derivatives 3b and 3c which are substituted in the vinylic positions. On heating 1d and 1i rearrange to yield 9trimethylstannylbarbaralane (2d) and its plumbyl analogue 2i quantitatively. The reactivity decreases on passing from 1i to 1d whereas 1h does not react. Mercury and zinc derivatives of 1 are so labile that only dibarbaralylmercury (2j) and zinc (2k) are observed by NMR spectroscopy. The title rearrangement proceeds by a 1,5homodienyl metallatropic shift which involves an endo1type transition structure. The new compounds 1b i, 2d, 2i, 3b and 3c are characterized with emphasis on the NMR data including 1H, 13C, 119Sn, 207Pb signal shifts and various heteronuclear couplings. Copyright 1993 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim

published proceedings

  • CHEMISCHE BERICHTE-RECUEIL

altmetric score

  • 3

author list (cited authors)

  • BLUMEL, J., & KOHLER, F. H.

citation count

  • 4

complete list of authors

  • BLUMEL, J||KOHLER, FH

publication date

  • January 1993

publisher