SYNTHESIS OF GERMATRANYL DERIVATIVES OF ESTERS OF CARBOXYLIC-ACIDS VIA ORGANOMETALLIC (SI, GE, SN) REAGENTS

Trialkylstannyl esters of tris(2-hydroxyalkyl) amines, N(CH(2)CHROSnAl k(3))(3) (9-11) (R = H, Me; Alk = Et, Bu), react with X3GeC(R-1)(R-2)C OOR3 (12-17) (X = Cl or Br; R-1, R-2 = H, Me, Ph, SiMe3, COOEt; R-3 = Me, Et) to give esters of alpha-germatranylcarboxylic acids, N(CH2CHRO )(3)GeC(R-1)(R-2)-COOR3 (1-8), in high yields. The synthesis of esters 12-17 is reported. Esters of alpha-germatranyldiphenylacetic acid 24 and 25 can be obtained by treatment of diphenylketene with Et3SnOMe to give in situ Et3SnC(Ph-2)COOMe (23), followed by reaction with GeCl4 to give in situ Cl3GeC(Ph-2)COOMe (22) and further reactions with 9 or 11, respectively. Reduction of germatrane 6 with LiAlH4 in diethyl et her leads to cleavage of the germanium-carbon bond with subsequent for mation of (2-hydroxyethyl)trimethylsilane. The crystal structures of 3 , 6, and 7 are reported, 1-Acyloxygermatranes 26 and 27 are obtained b y treatment of 1-methoxygermatrane (28) with diphenyl- and dichloroace tic acid, respectively.