Properties of 13C-N.M.R. spectra of O-(1-carboxyethylidene) derivatives of methyl β-d-galactopyranoside: models for determination of pyruvic acid acetal structures in polysaccharides
作者:Philip A.J. Gorin、Mytosk Mazurek、Helena S. Duarte、Marcello Iacomini、José H. Duarte
DOI:10.1016/s0008-6215(00)81021-6
日期:——
could be assigned a structure corresponding, in the positions of acetal substitution and acetal configuration, to structure 6 . Compound 6 (barium salt) is of interest as its 13 C-n.m.r. spectrum lacks non-protonated carbonyl and acetal carbonresonances, when obtained by the usual procedures. While this is principally because of long T 1 values, the non-protonated acetal carbon signals are comparatively
A selective ring opening reaction of 4,6-O-benzylidene acetals in carbohydrates using trialkylsilane derivatives
作者:Masahiro Sakagami、Hiroshi Hamana
DOI:10.1016/s0040-4039(00)00877-7
日期:2000.7
Reductive ringopeningreactions of 4,6-O-benzylidene-protected carbohydrates to the corresponding benzyl ethers using trialkylsilane derivatives were examined. When Et3SiH(or PS-DES™)-TfOH was used, 6-O-benzyl ethers with 4-hydroxy unsubstituted were obtained, while, when Et3SiH(or PS-DES™)-PhBCl2 was used, 4-O-benzyl ethers with 6-hydroxy unsubstituted were obtained in quantitative yield with excellent