Access to Fully Alkylated Germanes by B(C6F5)3-Catalyzed Transfer Hydrogermylation of Alkenes
摘要:
Various cyclohexa-2,5-dien-1-yl-substituted germanes are shown to serve as easy-to-handle surrogates of hydrogermanes, including gaseous MeGeH3 and Me2GeH2; The Ge-H functional group is liberated by treatment with catalytic amounts of B(C6F5)(3) and participates in situ in the B(C6F5)(3)-catalyzed hydrogermylation of alkenes. The range of suitable alkenes is broad, and the overall procedure provides a convenient access to tetraalkyl-substituted germanes at room temperature. Transfer hydrogermylation of internal alkynes works equally well and selectively forms the trans or cis diastereomer depending on the electronic bias of the C C bond.
Homologous compounds of the linalool type R(CH3)2E]-OH (with R = C6H5CH2 and C6H5CH2CH2) as well as their derivatives R(CH3)2El-OCH3 and [R(CH3)2El]2O show, in dependence of El = C, Si, Ge and Sn partly similar, but sometimes very different characteristics of odor. Unexpected are high qualities of fragrance with El = Ge, whereas derivatives with El = Sn remain scentless, obviously owing to polymerization. Noteworthy are the strong differences of odor in the system C6H5CH2El(CH3)3 from C via Si and Ge up to Sn, standing fully contrary to the postulation of Amoore whereupon smell qualities are only controlled by size and shape of molecules.C6H5CH2Sn(CH3)2OH (A1Sn) crystallizes as poly-mu-hydroxo-benzyldimethyltin with an one dimensional Sn-O-Sn-O chain (Sn-O 2.17(9) and 2.29(9) angstrom) in the monoclinic space group C2 (a = 12.696(4), b = 4.181(2), c = 10.626(3) angstrom and beta = 106.8(3)degrees).