Influence of protecting groups on the anomeric equilibrium; case of the 4,6-O-benzylidene acetal in the mannopyranose series
作者:Indrajeet Sharma、Luis Bohé、David Crich
DOI:10.1016/j.carres.2012.05.025
日期:2012.8
replacement of the 4- and 6-O-benzyl ethers in 2,3,4,6-tetra-O-benzyl-α,β-mannopyranose by a 4,6-O-benzylidene acetal results in an increased population of the β-anomer at equilibrium in CDCl(3) solution. The phenomenon is considered to arise from the lower steric bulk of the benzylidene acetal that, through diminished buttressing interactions, reduces steric interactions normally present in the β-anomer
据报道,用4,6-O-亚苄基乙缩醛代替2,3,4,6-四-O-苄基-α,β-甘露吡喃糖中的4-和6-O-苄基醚会导致在CDCl(3)解决方案中处于平衡状态的β-端基异构体的数量增加。该现象被认为是由亚苄基乙缩醛的较低空间体积引起的,其通过减少的支撑相互作用减少了通常存在于β-异头物中的空间相互作用。