121817-71-8Relevant articles and documents
Tetracoordinate borates as catalysts for reductive formylation of amines with carbon dioxide
Du, Chen-Xia,Huang, Zijun,Jiang, Xiaolin,Li, Yuehui,Makha, Mohamed,Wang, Fang,Zhao, Dongmei
supporting information, p. 5317 - 5324 (2020/09/17)
We report sodium trihydroxyaryl borates as the first robust tetracoordinate organoboron catalysts for reductive functionalization of CO2. These catalysts, easily synthesized from condensing boronic acids with metal hydroxides, activate main group element-hydrogen (E-H) bonds efficiently. In contrast to BX3 type boranes, boronic acids and metal-BAr4 salts, under transition metal-free conditions, sodium trihydroxyaryl borates exhibit high reactivity of reductive N-formylation toward a variety of amines (106 examples), including those with functional groups such as ester, olefin, hydroxyl, cyano, nitro, halogen, MeS-, ether groups, etc. The over-performance to catalyze formylation of challenging pyridyl amines affords a promising alternative method to the use of traditional formylation reagents. Mechanistic investigation supports electrostatic interactions as the key for Si/B-H activation, enabling alkali metal borates as versatile catalysts for hydroborylation, hydrosilylation, and reductive formylation/methylation of CO2.
Photochemical and thermal isomerization processes of a chiral auxiliary based donor-acceptor substituted chiroptical molecular switch: Convergent synthesis, improved resolution and switching properties
Van Delden, Richard A.,Hurenkamp, Johannes H.,Feringa, Ben L.
, p. 2845 - 2853 (2007/10/03)
A new type of chiroptical molecular switch is presented where irradiation employing different wavelengths of light induces a reversible helix inversion of a sterically overcrowded alkene bearing a second chiral entity in the form of a stereogenic center present in a pyrrolidine unit. The additional stereogenic center in the chiral auxiliary group has a distinct influence on the switching selectivity of this system and greatly facilitates the resolution of the different diastereoisomers, which is a considerable improvement compared with previously reported systems. In addition, the pyrrolidine stereogenic center causes small energetic differences between the various states of the switch system resulting in a small but significant directional preference in the helix inversion steps.
Asymmetric Diels-Alder Reactions with Sulfines Derived from Proline
Broek, Leon A. G. M. van den,Porskamp, Pascal A. T. W.,Haltiwanger, R. Curtis,Zwanenburg, Binne
, p. 1691 - 1695 (2007/10/02)
The Synthesis of a variety of sulfines 8 derived from S-proline, utilizing the reaction of α-silyl carbanions with sulfur dioxide, is described.Reaction of the thus prepared sulfines 8 with 2,3-dimethyl-1,3-butadiene gave dihydrothiopyran S-oxides 9.During these cycloaddition reactions asymmetric inductions up to 40percent were observed.From one pure diastereomeric form of cycloadduct 9d an X-ray analysis was carried out in order to provide insight in the steric course of the cycloaddition reaction.
