Microwave-Assisted Organocatalytic Anomerization of α-C-Glycosylmethyl Aldehydes and Ketones
摘要:
[GRAPHICS]The use of L-proline (30 mol %) and MW irradiation (13 W) with cooling promotes in a few hours the almost quantitative anomerization of alpha-C-glycosylmethyl aldehydes into beta-isomers. An open-chain enamine-based mechanism is postulated for this transformation. The anomerization of alpha-ketones was instead achieved by the pyrrolidine/TFA couple and MW irradiation at 120 degrees C (enamine mechanism) and by DBU as Bronsted base (enolate mechanism).
One-pot synthesis of 1-allyl- and 1-allenyl-6-O-acetyl-2,3,4-tri-O-benzyl-α-D-glycosides from methyl tetra-O-benzyl-α-D-glycosides
作者:Shang-Cheng Hung、Chun-Cheng Lin、Chi-Huey Wong
DOI:10.1016/s0040-4039(97)01204-5
日期:1997.8
A one-pot synthesis of 1-allyl- and 1-allenyl-6-O-acetyl-2,3,4-tri-O-benzyl-alpha-D-glycosides from the corresponding methyl per-benzyl-a-D-glycosides and allyl trimethylsilane or propargyl trimethylsilane in the presence of trimethylsilyl trifluoromethanesulfonate followed by addition of acetic anhydride in good yields was described. (C) 1997 Elsevier Science Ltd.