Cyclization vs. Elimination Reactions of 5-Aryl-5-hydroxy 1,3-Diones: One-Pot Synthesis of 2-Aryl-2,3-dihydro-4H-pyran-4-ones
作者:Rasheed Ahmad Khera、Rasheed Ahmad、Ihsan Ullah、Obaid-Ur-Rahman Abid、Olumide Fatunsin、Muhammad Sher、Alexander Villinger、Peter Langer
DOI:10.1002/hlca.201000015
日期:——
step by cyclocondensation of 1,3‐diketone dianions with aldehydes. The use of HCl (10%) for the aqueous workup proved to be very important to avoid eliminationreactions of the 5‐aryl‐5‐hydroxy 1,3‐diones formed as intermediates. The TiCl4‐mediated cyclization of a 2‐aryl‐2,3‐dihydro‐4H‐pyran‐4‐one with 1,3‐silyloxybuta‐1,3‐diene resulted in cleavage of the pyranone moiety and formation of a highly functionalized
One-pot synthesis of 6-aryl-2,3-dihydro-4H-pyran-4-ones by cyclocondensation of 1,3-diketone dianions with aldehydes
作者:Rasheed Ahmad、Rasheed Ahmad Khera、Alexander Villinger、Peter Langer
DOI:10.1016/j.tetlet.2009.03.189
日期:2009.6
6-Aryl-2,3-dihydro-4H-pyran-4-ones were prepared in one step by cyclocondensation of 1,3-diketone dianions with aldehydes. The use of hydrochloric acid (10%) for the aqueous work-up proved to be very important. (C) 2009 Elsevier Ltd. All rights reserved.
Brønsted Acid Promoted Cyclization of Cross-Conjugated Enynones into Dihydropyran-4-ones
作者:Steve Saulnier、Stanislav V. Lozovskiy、Alexander A. Golovanov、Alexander Yu. Ivanov、Aleksander V. Vasilyev
DOI:10.1002/ejoc.201700423
日期:2017.7.7
In triflic acid or sulfuric acid, diaryl-substituted cross-conjugated enynones undergo addition of the acid to the carbon–carbon triple bond to afford the corresponding vinyl triflates or sulfates. The vinyl triflates are stable under aqueous workup, whereas the vinyl sulfates are hydrolyzed to α,β-unsaturated 1,3-diketones (existing as conjugated enol forms). Extended reaction times lead to cyclization