An Eight-Membered Cyclic C,N-Bis(germadiyl) Bis(ketenimine)
摘要:
The reaction of tert-butyllithium with (fluorodimesitylgermyl)- and (chlorodimesitylgermyl)phenylacetonitrile (4a,b) leads to the lithium salts 5a (X = F) and 5b (X = Cl), which exhibit an ambident character: [> C--C=N <----> > C=C=N-]Li+. Quenching of 5a with triphenylbromomethane affords the germylketenimine 8, Mes(2)FGeC(Ph)=C=NCPh3. H-1 dynamic NMR spectroscopy allows the determination of the activation energy of the nitrogen inversion Delta G* = 9.9 +/- 0.2 kcal/mol. In the absence of a trapping reagent, 5 undergoes an elimination of lithium halide with formation of the eight-membered cyclic C,N-bis(germadiyl) bis(ketenimine) 1, which is the first ring containing two ketenimine moieties. 1 has been characterized by IR (nu(C=C=N) 2015 cm(-1)) and C-13 NMR spectroscopy (170.87 ppm for the sp carbon) and by an X-ray structure determination, which displays a "cyclohexane" type structure in a chair conformation.
The germene Mes2GeCR21 (Mes = 2,4,6-trimethylphenyl, CR2 = fluorenylidene) reacts with 5-methoxy-1,4-naphthoquinone to yield, via the o-quinodimethane 8, the endoperoxyde 9 by simple reaction with molecular oxygen. By contrast, 1 with 2,3-dichloro-1,4-naphthoquinone gives the tetracyclic compound 7 by a double [2 + 4] cycloaddition between the GeC doublebond and the conjugated system OC–CHCH. The
A new stablegermaphosphene, the 2,2-dimesityl-1-(2,4,6-triipropylphenyl)germaphosphene (1), has been made. It reacts quantitatively with benzaldehyde and α-phenyl-N-tert-butylnitrone to afford, by [2+2]- and [2+3]-cycoloadditions, respectively, the correponding four- and five-membered heterocycles 10 and 13. The conformations of these heterocycles are discussed. The reactions of 1 and 2,2-dimensityl-1-(2
Dimesitylfluoro(trichloromethyl)germane (1) has been synthesized from difluorodimesitylgermane, chloroform, and n-butyllithium. Addition of n-butyllithium to compound 1 gave the lithium carbenoid Mes2(F)Ge−C(Li)Cl2 (2), which behaves as a synthetic equivalent of the C-dichlorogermene Mes2GeCCl2 (5). Warming 2 to room temperature afforded the 1,2-digermylalkene Mes2(F)Ge−CClCCl−Ge(Cl)Mes2 (6) possibly