Synthesis and First Applications of a New Chiral Auxiliary (tert-butyl 2-(tert-butyl)-5,5-dimethyl-4-oxoimidazolidine-1-carboxylate)
作者:Armido Studer、Tobias Hintermann、Dieter Seebach
DOI:10.1002/hlca.19950780512
日期:1995.8.9
from L-alanine (Schemes 1 and 2). The parent heterocycle, 2-tert-butyl-5,5-dimethylimidazolidin-4-one (12; from 2-aminoisobutyramide, H-Aib-NH2, and pivalaldehyde) was also available in both enantiomeric forms by resolution with O,O′-dibenzoyltartaric acid. The compound (R)- or (S)-11 was used as an auxiliary, but also as a chiral Aib building block in a dipeptide synthesis. The 3-propanoyl derivative
由L-丙氨酸制备2-(叔丁基)-5,5-二甲基-4-氧代咪唑烷-1-羧酸叔丁基酯的两种对映体(11; Bbdmoic)(方案1和2)。母体杂环2-叔丁基-5,5-二甲基咪唑啉丁-4-酮(12; 2-氨基异丁酰胺,H-Aib-NH 2和新戊醛)也可用对映体形式通过O,O拆分得到′-二苯甲酰基酒石酸。化合物(R)-或(S)-11在二肽合成中,其用作助剂,但也用作手性Aib构建基块。3-丙酰基衍生物13的(- [R )- 11被用于对映体纯的2-甲基-3-苯基丙酸(对映体比(ER)99.5:0.5)的制备,通过Zn的烯醇化物(的苄基14 ;方案3)。衍生自庚二酸和(S)-11(23)的双烯醇酸酯的氧化偶联以及助剂的甲醇分解反应制得的二甲基反式-环戊烷-1,2-二羧酸酯(26)的er为93:7(方案5)图5)。3-(Boc-Gly)-Bbdmoic衍生物29被双重去质子化,并且在添加被烷基,苄基或烯丙基卤化物烷基化的ZnBr