Phenylethyl acetal

半缩醛semiacetal

　　醛的水合物 RCH（ OH） 2 和 2分子的醇 R′ OH以醚键结合的 RCH（ OR′） 2 称为缩醛（ acetal），与一分子醇结合的 RCH（ OH） OR′称为半缩醛（ semia－ cetal或 hemiacetal）。在戊糖以上的糖分子中，羰基和羟基结合而形成稳定的环状半缩醛结构，较之游离醛更为稳定。此时，可因五碳环、六碳环的形成，以及羟基的方向而产生异构体。  

Backbone Amide Linker Strategy: Protocols for the Synthesis of C-Terminal Peptide Aldehydes

aldehydes. The C-terminal aldehyde is masked as an acetal during synthesis and then conveniently demasked in the final cleavage step to generate the free aldehyde. Another application is in the synthesis of peptide thioesters with a C-terminal glycine.

Reversible Biotinylation of the 5′‐Terminus of Oligodeoxyribonucleotides and its Application in Affinity Purification

of two reversible biotinylation phosphoramidites and their application in labeling and affinity purification of synthetic oligodeoxyribonucleotides will be described. In both cases, the biotin is linked to the 5??terminus of DNA through a diisopropyl silyl acetal