Sterically crowded hexaalkyl benzene-1,2,3,4,5,6-hexakis[alpha-(alkoxycarbonyl)propanoates]. Synthesis and conformation analysis

摘要

A selective hexa-fold monoalkylation of the malonester carbanion (-)CH(COOR)(2) (R = Me, Et, t-Bu, Bn) with hexakis(bromomethyl)benzene afforded the title compounds 3 in a high-yield reactions. On subsequent replacement of the acid a-hydrogens with bulkier substituents, the title compounds 3, R = Et, provided a broad variety of the alpha-X-persubstituted homologues and derivatives 4 (X = Me, Et, Bu, Oc, Bn, Br, N-3). The effect of the variable X substituent on conformation was investigated by single-crystal X-ray diffraction and compared with the results obtained by theoretical calculation. [References: 24]