Cobalt‐Catalyzed Transfer Hydrogenation of α‐Ketoesters and
<i>N</i>
‐Cyclicsulfonylimides Using H
<sub>2</sub>
O as Hydrogen Source
作者:Yang Gao、Xuexin Zhang、Ronibala Devi Laishram、Jingchao Chen、Kangkui Li、Keyang Zhang、Guangzhi Zeng、Baomin Fan
DOI:10.1002/adsc.201900636
日期:2019.9.3
A Co‐catalyzed effective transferhydrogenation of various α‐ketoesters and N‐cyclicsulfonylimides by safe and environmentally benign H2O as hydrogensource is described. The reaction used easily available and easy to handle zinc metal as a reductant. Interestingly, the catalytic system does not require ligand for reduction of N‐cyclicsulfonylimides.
A metal‐free method for reduction of cyclic N‐sulfonyl ketimines catalyzed by B(C6F5)3, using commercially available methylphenylsilane as a reducing reagent under mild conditions has been developed. This reductive method was effective, not only providing the expected cyclic N‐Sulfonamides in good to excellent yields, but also showing good functional‐group tolerance.
开发了一种无金属的方法,在温和的条件下,使用市售的甲基苯基硅烷作为还原剂,还原由B(C 6 F 5)3催化的环状N-磺酰基酮亚胺。这种还原方法是有效的,不仅可以提供预期的环状N-磺酰胺类化合物,而且产率很高,而且显示出良好的官能团耐受性。
H8‐BINOL‐Derived Chiral η6‐Benzene Ligands: New Opportunities for the Ruthenium‐Catalyzed Asymmetric C−H Activation
作者:Junxuan Li、Guodong Wang、Weicong Guo、Jijun Jiang、Jun Wang
DOI:10.1002/anie.202405782
日期:——
A class of (S)-H8-BINOL-derived chiral η6-benzene ligands has been developed, which can coordinate with ruthenium(II) highly site-selectively.The related chiralruthenium(II) catalysts proved highly effective for the asymmetric C−H activation of N-sulfonyl ketimines with alkynes, affording a series of chiral spirocyclic sultams in up to 99 % yield with up to >99 % ee.
Iodotrimethylsilane and Catalytic Iodine Promoted Cyclization for the Facile Synthesis of 3-Monoarylated Five-Membered Benzosultams
作者:Zhao-Peng Liu、Yue-Hui Dong、Qiong-Wei Ni、Shu-Tao Ma
DOI:10.3987/com-09-11884
日期:——
3-Monoarylated five-membered benzosultams with various functional groups were prepared by simple and convenient two-step procedures. N-t-Bu-benzenesulfonamides were lithiated and reacted with substituted aromatic aldehydes to form the corresponding carbinols, which were converted to the cyclic compounds via a sequence of consecutive processes mediated by TMSCl-NaI-MeCN reagent and catalytic amount of iodine. Iodine played a crucial role in the eliminating the reductive side reaction in the cyclization processes.
Efficient visible-light photocatalytic aerobic oxidation of cyclic sulfamides to imines
A highly efficient photocatalyticaerobicoxidation of cyclic sulfamides to synthesize cyclic N-sulfonyl imines with Ir(ppy)2(dtbpy)PF6 as photocatalyst is reported. These environmentally friendly transformations exihibit good to excellent isolated yields and good generality with respect to both five-membered and six-membered cyclic sulfamides.