Chemo- and regioselective reductive transposition of allylic alcohol derivatives <i>via</i> iridium or rhodium catalysis
作者:Rylan J. Lundgren、Bryce N. Thomas
DOI:10.1039/c5cc07993d
日期:——
The selective, catalytic deoxygenation of alcohols remains a persistent challenge in organic synthesis. Pd-catalyzed formate reduction and diazene-mediated reductivetransposition are both valuable strategies for the selective deoxygenation of allylic...
The regiospecific nucleophilic substitution during the ruthenium catalyzed allylicalkylation of 1,3-unsymmetrical disubstituted allylic esters was demonstrated. The nucleophile was selectively introduced at the position originally substituted with leaving group in the 2-DPPBA or ip-pybox ligated [RuCl2(p-cymene)]2 catalyzed allylicalkylation of 1,3-unsymmetrical disubstituted allylic esters. The
stereodivergent Pd/Cu catalyst system has been developed for the unprecedented dynamickineticasymmetrictransformation (DyKAT) of racemic unsymmetrical 1,3-disubstituted allylic acetates with prochiral aldimine esters. A series of α,α-disubstituted α-amino acids bearing vicinal stereocenters were easily prepared with excellent enantioselectivities (up to >99% ee) and diastereoselectivities (up to >20:1 dr). By
Electrochemical carboxylation of benzylic carbonates was successfully performed as an alternative method for the synthesis of phenylacetic acids by using a one-compartment cell equipped with a Pt plate cathode and an Mg rod anode in CH3CN to afford the corresponding phenylacetic acids in good yields.
Synthesis of (<i>S</i>)-Imperanene by Using Allylic Substitution
作者:Yuji Takashima、Yuichi Kobayashi
DOI:10.1021/jo900854p
日期:2009.8.21
Synthesis of (S)-imperanene (1) was studied by using copper-assisted allylic substitution of ArCH═CHCH(L)CH2Ar (L: leaving group) and (i-PrO)Me2SiCH2MgCl. Preliminary substitution between PhCH═CHCH(L)Me (L = AcO, PivO, MeOCO2, (2-Py)CO2) and Bu copper reagents derived from BuMgX (X = Br, Cl) and CuBr·Me2S or CuCl in 1:1−40:1 ratios suggested acetate 28 as the best substrate. To prepare 28, kinetic
通过使用铜辅助的ArCH = CHCH(L)CH 2 Ar(L:离去基团)和(i- PrO)Me 2 SiCH 2 MgCl的烯丙基取代研究了(S)-紫杉醇(1)的合成。PhCH═CHCH(L)Me(L = AcO,PivO,MeOCO 2,(2-Py)CO 2)和由BuMgX(X = Br,Cl)和CuBr·Me 2 S或CuCl衍生的Bu铜试剂之间的初步取代以1:1−40:1的比例建议乙酸盐28是最好的底物。为制备28,外消旋(E)-TMSCH═CHCH(OH)CH 2 Ar 2(Ar 2 =(通过使用与(-)-DIPT的不对称环氧化进行的对-TBSO)(m- MeO)C 6 H 3),得到相应的环氧醇和(S)-烯丙基醇。经色谱分离后,这些产物转化为(S,E)-Bu 3 SnCH = CHCH(OH)CH 2 Ar 2,经钯催化与Ar 2 -I偶联,然后乙酰化,得到28(95-98% ee)。用(i