Synthesis of Germatranyl Derivatives of Esters of Carboxylic Acids via Organometallic (Si, Ge, Sn) Reagents

Abstract

AbstractTrialkylstannyl esters of tris(2‐hydroxyalkyl)amines, N(CH2CHROSnAlk3)3 (9‐11 (R = H, Me; Alk = Et, Bu), react with X3GeC(R1)(R2)COOR3 (12–17) (X  Cl or Br; R1, R2=H, Me, Ph, SiMe3, COOEt; R3=Me, Et) to give esters of α‐germatranylcarboxylic acids, N(CH2CHRO)3GeC(R1)(R2)‐COOR3 (1–8), in high yields. The synthesis of esters 12–17 is reported. Esters of α‐germatranyldiphenylacetic acid 24 and 25 can be obtained by treatment of diphenylketene with Et3SnOMe to give in situ Et3SnC(Ph2)COOMe (23), followed by reaction with GeCl4 to give in situ Cl3GeC(Ph2)COOMe (22 and further reactions with 9 or 11, respectively. Reduction of germatrane 6 with LiAlH4 in diethyl ether leads to cleavage of the germanium‐carbon bond with subsequent formation of (2‐hydroxyethyl)trimethylsilane. The crystal structures of 3, 6 and 7 are reported. 1‐Acyloxygermatranes 26 and 27 are obtained by treatment of 1‐methoxygermatrane (28) with diphenyl‐ and dichloroacetic acid, respectively.