亲核试剂交换实验用于监测苄基胺向π-烯丙基铝配合物的亲核加成反应的可逆性。在DMF和二氯甲烷中,Dppe,dppp,dppb和PHOX的交换率均高于PPh 3和dppm。通过添加DBU或Cs 2 CO 3可以抑制交叉反应,但是使用Cs 2 CO 3可以消除二烯副产物的交换。使用PHOX配体对交换百分比对反应完成百分比的分析表明,添加DBU或Cs 2 CO 3交换仅在达到100%完成后才开始。
亲核试剂交换实验用于监测苄基胺向π-烯丙基铝配合物的亲核加成反应的可逆性。在DMF和二氯甲烷中,Dppe,dppp,dppb和PHOX的交换率均高于PPh 3和dppm。通过添加DBU或Cs 2 CO 3可以抑制交叉反应,但是使用Cs 2 CO 3可以消除二烯副产物的交换。使用PHOX配体对交换百分比对反应完成百分比的分析表明,添加DBU或Cs 2 CO 3交换仅在达到100%完成后才开始。
New Monodentate P,C-Stereogenic Bicyclic Phosphanes: 1-Phenyl-1,3a,4,5,6,6a-hexahydrocyclopenta[b]phosphole and 1-Phenyloctahydrocyclopenta[b]phosphole
作者:Zbigniew Pakulski、Oleg M. Demchuk、Jadwiga Frelek、Roman Luboradzki、K. Michał Pietrusiewicz
DOI:10.1002/ejoc.200400186
日期:2004.9
diastereomerically pure salts to the corresponding enantiomerically pure phosphane oxides. Stereoretentive reduction of P=O in (RP)-6 gave enantiomerically pure (SP)-4. Hydrogenation of (SP)-6 and subsequent reduction of P=O afforded saturated 1-phenyloctahydrocyclopenta[b]phosphole [(RP)-5]. Monophosphanes (SP)-4 and (RP)-5 were tested as chiral ligands and catalysts in model asymmetric hydrogenation and
Fluorinated Alcohols As Promoters for the Metal-Free Direct Substitution Reaction of Allylic Alcohols with Nitrogenated, Silylated, and Carbon Nucleophiles
作者:Paz Trillo、Alejandro Baeza、Carmen Nájera
DOI:10.1021/jo301049w
日期:2012.9.7
very general, since different nitrogenated nucleophiles and carbonnucleophiles can be used achieving high yields, especially when HFIP is employed as solvent and aromatic allylic alcohols are the substrates. Thus, sulfonamides, carbamates, carboxamides, and amines can be successfully employed as nitrogen-based nucleophiles. Likewise, silylated nucleophiles such as trimethylsilylazide, allyltrimethylsilane
The first P-chirogenic mono- and diphosphine ligands supported on the upper rim of a calix[4]arene moiety were synthesized using the ephedrine methodology. The lithiated calix[4]arenemono- and dianions both react with the oxazaphospholidine–borane, prepared from ephedrine, to afford regio- and stereoselectively the corresponding calix[4]arenyl aminophosphine–boranes, by cleavage of the heterocyclic
使用麻黄碱方法合成了支撑在杯[4]芳烃部分上缘的首个P-手性单-和二膦配体。锂化的杯[4]亚芳基单价和二价阴离子均与由麻黄碱制得的恶唑磷环烷-硼烷反应,通过在P-处裂解杂环,选择性和立体选择性地提供相应的杯[4]芳基氨基膦-硼烷。 O键位置。随后与HCl反应,然后与有机锂试剂反应,最后与DABCO分解,生成相应的杯[4]芳基单或二膦。通过使用(+)-或(-)-麻黄碱或通过在合成过程中改变有机锂试剂的添加顺序来获得杯[4]芳基膦的两种对映体。在手性钯络合物存在下的31 P NMR。通过对其晶体硼烷配合物进行X射线分析,确定了单膦基杯和二膦基杯[4]芳烃的绝对构型。测试了P-手性产杯[4]芳基膦在不对称钯催化下丙二酸二甲酯或苄胺对(E)-1,3-二苯基丙-2-烯-1-基乙酸酯的钯催化的烯丙基取代。当使用双甲基苯基膦基杯[4]芳烃时,得到的烯丙基产物的ee分别为82%和79%。在这两种情况下,使
New chiral phosphinoimidazolidine ligand in palladium-catalyzed asymmetric allylic substitution
作者:Myung-Jong Jin、Sang-Han Kim、Sang-Joon Lee、Young-Mok Kim
DOI:10.1016/s0040-4039(02)01676-3
日期:2002.10
Chiral phosphinoimidazolidine 3 was used as an excellent ligand in Pd-catalyzed asymmetric allylic alkylation of racemic 1,3-diphenyl-2-propenyl acetate 5 with dimethyl malonate. Outstanding enantioselectivity of up to 99% and remarkable catalytic activity were observed. The ligand was also found to be effective in the asymmetric allylic amination of 5 with benzylamine.