PREPARATION AND STRUCTURE OF NEW DIAZASELENURANES - TRANSANNULAR HYPERVALENT BOND BETWEEN SELENO AND DIAMINO GROUPS

The transannular reaction of N-benzyl derivatives of oaminomethano)-5H ,7H-dibenzo[b,g][1,5]selenazocine (1 and 2) with N-bromosuccinimide (N BS) gave an aminoammonio-selenurane 4 which is the first example of an isolable diazaselenurane with two unsymmetrical apical nitrogen ligan ds of tertiary amino- and quaternary ammonio-groups. X-ray analysis of the aminoammonioselenurane Br- salt (4a) showed the twin-boat form; t he distances of Se ... N are 1.918 Angstrom and 2.419 Angstrom respect ively. The structure of selenurane 4 in solution was confirmed by Se-7 7 and N-15 NMR spectroscopy using the N-15-enriched aminoammonio-selen urane 4-N-15. The apical tertiary amine of selenurane 4 behaves as a n ucleophile toward benzylbromide to give the bisammonio-selenurane 5. T he aminoammonio and bisammonio-selenuranes 4 and 5 were converted into the neutral amines upon treatment with 2 equiv. of SmI2. Copyright (C ) 1996 Elsevier Science Ltd .