Iridium‐Catalyzed Enantioselective Transfer Hydrogenation of Ketones Controlled by Alcohol Hydrogen‐Bonding and
<i>sp</i>
<sup>3</sup>
‐C−H Noncovalent Interactions
Iridium‐catalyzed enantioselective transfer hydrogenation of ketones with formic acid was developed using a prolinol‐phosphine chiral ligand. Cooperative action of the iridium atom and the ligandthrough alcohol‐alkoxide interconversion is crucial to facilitate the transfer hydrogenation. Various ketones including alkyl aryl ketones, ketoesters, and an aryl heteroaryl ketone were competent substrates
Michael Addition of Stannyl Ketone Enolate to α,β-Unsaturated Esters Catalyzed by Tetrabutylammonium Bromide and an ab Initio Theoretical Study of the Reaction Course
作者:Makoto Yasuda、Kouji Chiba、Noriyuki Ohigashi、Yasuhiro Katoh、Akio Baba
DOI:10.1021/ja028853+
日期:2003.6.1
Michael addition of stannyl ketone enolates to alpha,beta-unsaturated esters was accomplished in the presence of a catalytic amount of tetrabutylammonium bromide (Bu(4)NBr). Other typical systems using lithium enolate or silyl enolate with catalysts (TiCl(4) or Bu(4)NF) failed to give the desired products. The bromide anion from Bu(4)NBr coordinates to the tin center in enolate to accelerate the conjugate
sequential C–C bond formation and cleavage of aromatic β-diketones with α,β-unsaturated esters is developed to obtain 1,5-ketoesters. The sequential reaction via Michael addition and retro-Claisen condensation proceeds smoothly under mild conditions in up to 98% isolated yield. The mechanism study disclosed that the cascade process involved C–C bond cleavage of aromatic β-diketone as a phenacyl donor under
开发了AK 2 CO 3催化的一锅法,涉及顺序形成C–C键并用α,β-不饱和酯裂解芳香族β-二酮,以获得1,5-酮酯。通过Michael加成反应和Retro-Claisen缩合反应的顺序反应可在温和条件下顺利进行,分离产率最高可达98%。机理研究表明,级联过程涉及在酒精碱性条件下芳族β-二酮作为苯甲酰基供体的C–C键裂解。
Photocatalyzed Triplet Sensitization of Oximes Using Visible Light Provides a Route to Nonclassical Beckmann Rearrangement Products
作者:Xiao Zhang、Tomislav Rovis
DOI:10.1021/jacs.1c10148
日期:2021.12.22
photoisomerization of oximes via visible-light-mediated energy transfer (EnT) catalysis. Facile access to (Z)-oximes provides opportunities to achieve regio- and chemoselectivity complementary to those of widely used transformations employing oxime starting materials. We show an enhanced one-pot protocol for photocatalyzed oxime isomerization and subsequent Beckmannrearrangement that enables novel reactivity with