size of the ester alkoxy group. The same products were obtained from the NBS treatment of methyl angelate (2b). This NBS-bromination appears to be thermodynamically controlled, since both angelic and tiglic acid as well as their methyl esters were brought into equilibrium (1 ⇆ 2 = > 9:1) with catalytic amounts of NBS.
tigtig甲酯(1b)的Wohl - Ziegler
溴化(N-
溴代琥珀
酰亚胺=
NBS)得到了γ-
溴代
甲基丙烯酸酯(3b)和β'-
溴代
甲基丙烯酸酯(5b)的2:1混合物。γ-
溴化与β'-
溴化的比率不受溶剂,催化剂或酯烷氧基基团尺寸变化的影响。从
NBS处理的
当归酸甲酯(2b)获得了相同的产品。这种
NBS溴化似乎是热力学控制的,因为当量的
NBS催化使天使酸和tiglic酸及其甲基酯达到平衡(1⇆2 => 9:1)时。