An Efficient, Stereoselective Approach to syn-1,2-Diols Protected as Cyclic Carbonates
摘要:
Enantioenriched 4-hydroxyalk-2-ynyl carbonates (or benzoates) have been prepared by stereoselective zinc-mediated addition of alkyl 2-propynyl carbonates (or their benzoate analogues) to aldehydes. Their partial reduction to Z-olefins followed by cyclization under mild Pd-catalyzed conditions allowed a straightforward access to enantioenriched syn-1,2-diols protected as cyclic carbonates.
Mild Rhodium(III)-Catalyzed C–H Allylation with 4-Vinyl-1,3-dioxolan-2-ones: Direct and Stereoselective Synthesis of (<i>E</i>)-Allylic Alcohols
作者:Shang-Shi Zhang、Jia-Qiang Wu、Ye-Xing Lao、Xu-Ge Liu、Yao Liu、Wen-Xin Lv、Dong-Hang Tan、Yao-Fu Zeng、Honggen Wang
DOI:10.1021/ol503229c
日期:2014.12.19
A rhodium(III)-catalyzed C–H direct allylation reaction with 4-vinyl-1,3-dioxolan-2-ones has been developed. The reaction provides a facile and stereoselective access to substituted-(E)-allylic alcohols under mild and redox-neutral reaction conditions. Olefinic C–H activation is applicable, giving multifunctionalized skipped dienes in good yields. Minimal double-bond migration was observed.
Air-Stable Manganese(I)-Catalyzed C−H Activation for Decarboxylative C−H/C−O Cleavages in Water
作者:Hui Wang、Mélanie M. Lorion、Lutz Ackermann
DOI:10.1002/anie.201702193
日期:2017.5.22
The decarboxylative C−H/C−O functionalization was accomplished by air‐ and water‐tolerant manganese(I) catalysis. The versatile C−H allylation occurred by facile organometallic C−H metalation on indoles, arenes, aminoacids and synthetically meaningful aryl ketimines with ample substrate scope and high levels of chemo‐, site‐ and regio‐selectivity.
脱羧的C / H / O功能化是通过耐空气和耐水的锰(I)催化完成的。通用的CH烯丙基化反应是由吲哚,芳烃,氨基酸和合成上有意义的芳基酮亚胺在分子上容易进行有机金属CH的金属化而形成的,具有足够的底物范围和高水平的化学,位点和区域选择性。
Cobalt(III)-Catalyzed Fast and Solvent-Free C–H Allylation of Indoles Using Mechanochemistry
Mechanochemical conditions have been applied to a highly efficient cobalt(III)-catalyzed C–H bond activation for the first time. In a subsequent step to the olefin insertion and β-oxygen elimination, N-pyrimidinylindoles were allylated with vinylethylene carbonates in the absence of organic solvent under high-speed ball-milling condition. As the reaction afforded the desired products in up to 98% yields
3-Bromopropenyl methyl carbonate reacts smoothly with aldehydes in the presence of zinc in a mixture of saturated aqueous NH 4 Cl and THF (9:1). Monoprotected alk-1-en-3,4-diols are formed in high yields and in short reaction times. The reaction is diastereoselective, saturated aldehydes afford anti-adducts, while α,β-unsaturated and aromatic aldehydes preferentially give the synisomers. Very simple