Lithiation and Stereoselective Transformations of 3-Aroyl-2,2,4,4-tetramethyloxazolidines (TMO Amides), a New Class of Acid-labile Atropisomeric Amides
作者:Mark Anstiss、Jonathan Clayden、Alexander Grube、Latifa H. Youssef
DOI:10.1055/s-2002-19748
日期:——
Arom. amides 4 (3-aroyl-2,2,4,4-tetramethyloxazolidines or TMO amides) derived by acylation of 2,2,4,4-tetramethyloxazolidine undergo ortho- and lateral lithiation reactions. Given sufficient steric hindrance to bond rotation, they exhibit atropisomerism about the Ar-CO bond and the Ar-CO axis is able to control the atroposelective formation of new stereogenic centers. For example, an 85:15 ratio of
芳香。通过 2,2,4,4-四甲基恶唑烷的酰化衍生的酰胺 4(3-芳酰基-2,2,4,4-四甲基恶唑烷或 TMO 酰胺)经历邻位和侧位锂化反应。给定足够的键旋转空间位阻,它们表现出关于 Ar-CO 键的阻转异构现象,Ar-CO 轴能够控制新立体中心的阻转选择性形成。例如,3-(2'-(1-羟丙基)-1'-萘甲酰基)-2,2,4,4-四甲基恶唑烷 (15a) 的顺式和反式异构体的比例为 85:15,从锂化的 3- (1'-萘酰基)-2,2,4,4-四甲基恶唑烷和 EtCHO。与受阻仲胺(如二异丙胺)衍生的酰胺不同,3-芳酰基-2,2,4,4-四甲基恶唑烷对酸敏感,用甲磺酸处理可通过在酰胺基团上环化产生内酯或内酰胺。例如,15a 以 62% 的产率得到 I。晶体和摩尔。3-(2-溴-5-甲氧基苯甲酰基)-2,2,4,4-四甲基恶唑烷和 (Ra*,S*)-3-(2'-(.α.-hydroxybenzyl)-1'-naphthoyl