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