Friedel-Crafts Arylation of α-Hydroxy Ketones: Synthesis of 1,2,2,2-Tetraarylethanones
作者:Anil Kumar、Tej V. Singh、Sajesh P. Thomas、Paloth Venugopalan
DOI:10.1002/ejoc.201403438
日期:2015.2
Friedel-Crafts arylation of a-hydroxy ketones such as 2-hydroxy- 1,2,2-triarylethanones has been achieved with a variety of arenes and heteroarenes in the presence of Lewis or Bronsted acids. Both sterically hindered and unhindered 1,2,2,2-tetrarylethanones are formed in good to excellent yields by using a stoichiometric amount of triflic acid. The intermediacy of an a-keto carbenium ion has been proposed
proposals of α-carbonyl cation intermediates have been driven by chemical intuition and indirect evidence. Recently, wide interest in α-carbonyl cation chemistry has opened new gates to prepare α-functionalized carbonyl compounds. Though these intrinsically unstable carbocations are formed under forcing conditions (e.g., in a strong acid medium), their fleeting existence prohibits direct observation
Transition-Metal-Free and Selective Deconstructive Carbonyl Olefination of α-Hydroxy Ketones: A Complementary Approach to Knoevenagel Reaction
作者:Anil Kumar、Sandeep Sandeep、Vaneet Saini、Chayawan Chayawan、Ganga R. Chaudhary、Paloth Venugopalan
DOI:10.1055/a-2114-7802
日期:2023.10
While the carbonylolefination has been extensively studied and well documented, use of α-hydroxy ketones as precursors for the carbonylolefination is not reported, till date. Herein, a transition-metal-free and selective Knoevenagel-type deconstructive carbonylolefination of α-hydroxy ketones using arylacetonitriles under mild reaction conditions is presented. The reaction affords valuable scaffolds
Indium(III) bromide catalyzed direct azidation of α-hydroxyketones using TMSN3
作者:Anil Kumar、Ramesh K. Sharma、Tej V. Singh、Paloth Venugopalan
DOI:10.1016/j.tet.2013.10.055
日期:2013.12
The direct catalytic azidation of 2-hydroxy-1,2,2-triarylethanones occurs at room temperature using 2 mol % of InBr3 as Lewis acid and TMSN3 as soluble azide source. 2-Azido-1,2,2-triarylethanones have been isolated in excellent yields. The role of aryl group and stereoelectronic factors indicate that the mechanism may involve the formation of a stable carbenium ion towards azidation. (C) 2013 Elsevier Ltd. All rights reserved.