Cleavage of Aromatic C–O Bonds via Intramolecular S<sub>N</sub>Ar Reaction and Preparation of <i>P</i>,<i>C</i>,<i>Axial</i>-Stereogenic Menthyl Phosphine Derivatives
Phosphine ligands with up to six chiral sites were prepared, starting from 2-phenylphenol, via O- and P-alkylation, cyclization, and coupling. The chirality was transferred from (L)-menthyl to phosphorus, α-carbon, and axis, to achieve excellent diastereoselectivities. During an intramolecular SNAr reaction with alkoxyl as the leaving groups, the C–O bond was converted to a C–C bond. Both phosphine
从2-苯基苯酚开始,通过O-和P-烷基化,环化和偶联,制备具有最多六个手性位点的膦配体。手性从(L)-薄荷基转移到磷,α-碳和轴上,以实现出色的非对映选择性。在以烷氧基为离去基团的分子内S N Ar反应中,C–O键转换为C–C键。膦硼烷和氧化物均可用于转化,从而提供一系列环状膦。
Novel asymmetric triorganotin hydrides containing the (−)-menthyl ligand
作者:Herbert Schumann、Birgit Corinna Wassermann
DOI:10.1016/0022-328x(89)87177-3
日期:1989.4
Synthesis and characterization of (−)-menthylmethyl-t-butyltin hydride and (−)-menthylmethylisopropyltin hydride, asymmetric triorganotin hydrides with the chiraltin center linked to a chiral carbon of an opticallyactive substituent, and of (−)-menthyldimethyltin hydride are reported.
The synthesis and physical properties of dineophyl(−)menthyltin (4) and methylneophyl (−)menthyltin (9) hydrides as well as that of their organotin precursors are described. Whereas the reduction of acetophenone with 4 afforded (−)-(S)-1-phenylethanol in 40% ee, the reduction of the same ketone with dimethyl(−)menthyltin hydride yielded the alcohol with only a 7% ee. Full 1H, 13C, and 119Sn NMR data
描述了恐龙的合成和物理性质(4)和甲基新叶藻(-)薄荷(9)氢化物及其有机锡前体的合成和物理性质。苯乙酮用4还原可得到40%ee的(-)-(S)-1-苯基乙醇,而相同的酮用二甲基(-)薄荷基氢化锡的还原得到的醇只有ee 7%。给出了全部1 H,13 C和119 Sn NMR数据。
Mechanistic Evaluation of the Halocyclization of 4-Penten-1-ol by Some Bis(2-substituted pyridine) and Bis(2,6-disubstituted pyridine)bromonium Triflates
作者:Xi-Lin Cui、R. S. Brown
DOI:10.1021/jo000449a
日期:2000.9.1
sensitive to the nature of the pyridine, the limiting values being 3-7 except in the case of bis(2(-)-menthylpyridine)bromonium triflate where the k(-)(d)/k(2) ratio is approximately 80. The reaction of 4-penten-1-ol and its OD isotopomer with bis(lutidine)bromonium triflate was investigated to determine the deuterium kinetic isotope effect (dkie) on the bromocyclization reaction. The (k(-)(d)/k(2))(H/D)
New Access Routes to Privileged and Chiral Ligands for Transition‐Metal Catalyzed Hydrogen Autotransfer (Borrowing Hydrogen), Dehydrogenative Condensation, and Alkene Isomerization Reactions
A group of transition-metal catalyzed hydrogen moving reactions, encompassing hydrogen autotransfer (HAT; also called borrowing hydrogen, BH), dehydrogenative condensation (DHC) and alkene isomerization, displays high atom economy and relies on widely available starting materials. Such reactions have considerable potential for clean reaction design and application in sustainable synthesis. With the