Highly efficient substitution of allylic picolinates with copper reagents derived from aryl-, alkenyl-, furyl-, and thienyl-lithiums
作者:Yohei Kiyotsuka、Yuichi Kobayashi
DOI:10.1016/j.tet.2009.11.052
日期:2010.1
R2=CH2OTBS), with phenylcopper reagents derived from salt free PhLi (2 equiv) and CuBr·Me2S (2 and 1 equiv, respectively) was highly promoted by MgBr2 (3 equiv), producing anti SN2′ product regio- and stereoselectively. This reagent system was proven to be general with several picolinates (R1, R2: Ph(CH2)2, PMBO(CH2)3, Me, TBSOCH2, PMBOCH2, c-Hex). Furthermore, aryl copper reagents prepared from ArLi, which
用衍生自苯基铜的试剂取代光学活性的烯丙基吡啶甲酸顺式R 1 -CH(OC(O)(2-Py))CH CHR 2(R 1 =(CH 2)2 Ph,R 2 = CH 2 OTBS)MgBr 2(3当量)高度促进了无盐PhLi(2当量)和CuBr·Me 2 S(分别为2和1当量),产生区域和立体选择性的抗S N 2'产物。事实证明,该试剂体系与几种吡啶甲酸(R 1,R 2:Ph(CH 2)2,PMBO(CH)2)3,Me,TBSOCH 2,PMBOCH 2,c -Hex)。此外,事实证明,由ArLi制备的芳基铜试剂可通过锂-卤素交换制得,与存在的MgBr 2交换量比交换产生的LiX量大的MgBr 2兼容。2-MeOC:取代不与芳基上铜板(Ar'的空间位阻干扰6 ħ 4,2,6-(MOMO)2 -4-MEC 6 ħ 2,2,6-ME 2 ç 6 ħ 3等)。同样,立体定义的顺式和反式烯基,呋喃基和噻吩基试剂可有效地产生相应的抗S