Symmetry swap: A C2‐chiral spiro diphosphine oxide (SpinPO) has been found to be highly efficient and enantioselective in the catalysis of double‐aldol reactions of ketones and aldehydes to give the corresponding optically active double‐aldol products, which can be readily transformed into optically active C3‐ and pseudo‐C3‐symmetric molecules.
Catalytic enantioselective synthesis of chiral spirocyclic 1,3-diketones <i>via</i> organo-cation catalysis
作者:Xiao-Yan Zhang、Ya-Ping Shao、Bao-Kuan Guo、Kun Zhang、Fu-Min Zhang、Xiao-Ming Zhang、Yong-Qiang Tu
DOI:10.1039/d1cc05205e
日期:——
provides convenient access to a range of enantioenriched spirocyclic 1,3-diketones in moderate to high yields and enantioselectivities and features a broad substrate scope in terms of enol lactones. The catalytic capability of this triazolium salt catalyst is also demonstrated in this enantioselective transformation, which could inspire its further application.
Spiro‐Bicyclic Bisborane Catalysts for Metal‐Free Chemoselective and Enantioselective Hydrogenation of Quinolines
作者:Xiang Li、Jun‐Jie Tian、Ning Liu、Xian‐Shuang Tu、Ning‐Ning Zeng、Xiao‐Chen Wang
DOI:10.1002/anie.201900907
日期:2019.3.26
A new series of spiro‐bicyclic bisborane catalysts has been prepared by means of hydroboration reactions of C2‐symmetric spiro‐bicyclic dienes with HB(C6F5)2 and HB(p‐C6F4H)2. When used for hydrogenation of quinolines, these catalysts give excellent yields and enantiomeric excesses, and show turnover numbers of up to 460. The most attractive feature of these metal‐free hydrogenation reactions was the
通过C 2对称螺双环二烯与HB(C 6 F 5)2和HB(p C 6 F 4 H)2的硼氢化反应制备了一系列新的螺双环双硼烷催化剂。当用于喹啉加氢时,这些催化剂具有出色的收率和对映体过量,并且显示出高达460的周转率。这些无金属加氢反应的最吸引人的特点是宽泛的官能团耐受性,使该方法可与现有方法互补喹啉加氢的方法。
1,6-Bis(5,2′ : 5′,2″-terthiophene-2-yl)spiro[4.4]nona-1,6-diene: a molecule having two orthogonally bisected α-terthiophene systems through a spiro carbon
作者:Juzo Nakayama、Toru Fujimori
DOI:10.1039/c39910001614
日期:——
The title compound 11, a molecule having two orthogonally bisected α-terthiophene systems through a spiro carbon, has been synthesized starting from spiro[4.4]nona-1,6-dione and 5,2â² : 5â²,2â²-terthiophene-2-ylcerium reagent.