Direct synthesis of 8-(α-bromomercuriethyl)-quinoline, a convenient model for studying reaction mechanisms

  • Published on
    12-Aug-2016

  • View
    212

  • Download
    0

Embed Size (px)

Transcript

  • DIRECT SYNTHESIS OF 8 - (~-BROMOMERCURIETHYL) -

    QUINOL INE, A CONVENIENT MODEL FOR STUDYING

    REACTION MECHANISMS

    O. A. Reutov , V. V. Bash i lov , and V. [. Soko lov

    UDC 542.91:547.254.9:547.831:541.124

    In order to study the s tereochemist ry of the react ions of organomercury compounds it is necessary to have optically active models in which the mercury atom is found in the chiral center. Recently, we used the d iastereomer ic L-menthyl esters of ~-mercur i -~-pheny lacet i c acid [1], the direct synthesis of which has been known for a long t ime [2], in the reaction with tris(triphenylphosphine)platinum(0).

    Now we have found that 8-(~-bromoethyl)quinol ine reacts when shaken with metal l ic mercury to give the chiral 8-(~-bromomercur iethyl)quinol ine (D. The compound is new. Attempts to obtain it by other methods, in part icu lar via the organolithium and -magnes ium compounds, were unsuccessful. The mercury derivative f rom 8-bromomethylquinol ine was obtained in s imi lar manner , but in lower yield.

    Since ~-bromoethylbenzene under analogous conditions does not form the mercury derivative, the determining factor in the case of 8-haloalkyl quinolines is apparently the possibi l i ty of having intramolecular cooperation of the react ion via the donor nitrogen atom. The favorable effect of an externainucleophi le was observed previously [3].

    Test react ions between 8-(~-bromomercuriethyl)quinol ine and Pb(0) complexes led to metal locycles of known chelate type [4].

    EXPERIMENTAL

    8 - (~-Bromomercur ie thy l )qu lno l ine (1). A mix ture of 5.0 g of 8-(~-bromoethyl)quinol ine and 5 ml of Hg was shaken in a thick-wal led flask for 3 h. The format ion of a colorless crystalline substance was observed dur ing shaking. The mixture was extracted with benzene and CH2CI 2. The combined extracts were filtered f rom the Hg, the CH2CI 2 was evaporated in vacuo, and the substance was precipitated f rom benzene solution with pentane. We obtained 2.8 g (30%) of (I), mp 156-157~ Rf 0.45 (Silufol, benzene). Infrared spect rum (KBr, 9, cm-l) : 2945, 2864 (CH~; 2893 (CH); 3099, 3080, 3061, 3037, 3013 (quinoline). Found: C 30.24; H 2.24; Br 18.89; Hg 45.48%. C l iH i0BrHgN. Calculated: C 30.25; H 2.31; Br 18.30; Hg 45.93%.

    8 -Bromomercur imethy lqu ino l ine (If). A mix ture of 2.5 g of 8 -bromomethy lqu ino l ine , 5.0 ml of Hg, and 5.0 g of NaBr in 20 ml of abs. ethanol was shaken for 5 h. The mixture was extracted with 75 rnl of CH2CI 2. The solution was filtered f rom the Hg and NaBr , evaporated in vaeuo to smal l vo lume, and the substance was precipitated with hexane. We obtained 0.6 g (12%) of (II), mp 157 ~ (decompn.) ( from EtOH). Found: C 28.62; H 1.84; Br 19.75; Hg 46.68%. C IoHsBrHgN. Calculated: C 28.42; H 1.91; Br 18.91; Hg 47.46%.

    CONCLUSIONS

    The preparat ion of the previously unknown chiral 8 - (~-bromomercur iethy l )qu ino l ine and 8 -bromomercur i - methylquinol ine by direct synthesis f rom the cor respond ing bromides and mercury was described.

    L ITERATURE C ITED

    I. O .A . Reutov, V. I. Sokolov, G. Z. Su le imanov, and V. V. Bashilov, J. Organomet . Chem. , 160, 7 (1978). 2. A .N . Nesmeyanov , O. A. Reutov, and S. S. Poddubnaya , Dokl. Akad. Nauk SSSR, 88_, 479 (i953). 3. M .E . Vol'pin, E. A. Tvdoradze , and K. P. Butin, Zh. Obshch. Kh im. , 40, 315 (1970). 4. L .L . Tro i tskaya, A. I. Grandberg , V. I. Sokolov, and O. A. Reutov, Dokl. Akad. Nauk SSSR, 228,367

    (1976).

    A. N. Nesmeyanov Institute of Heteroorgan ic Compounds , Academy of Sciences of the USSR, Moscow. Trans la ted f rom Izvestiya Akademi i Nauk SSSR, Ser iya Kh imicheskaya , No. 5, pp. 1169-1170, May , 1981. Original article submit ted October I0, 1980.

    928 0568-5230/81/3005-0928 $07.50 9 1981 Plenum Publishing Corporation