Premium
Selective Cyclodimerization and Cyclotrimerization of Acetals Bearing Electron‐Withdrawing Groups Catalyzed by Lewis Acids
Author(s) -
Maeda Sayuki,
Obora Yasushi,
Ishii Yasutaka
Publication year - 2009
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200900432
Subject(s) - chemistry , lewis acids and bases , selectivity , catalysis , yield (engineering) , medicinal chemistry , methylene , organic chemistry , materials science , metallurgy
Acetals like 3,3‐diethoxypropionate bearing electron‐withdrawing groups were found to undergo cyclodimerization and cyclotrimerization in the presence of Lewis acids to give coumalates and 1,3,5‐trisubstituted benzenes. The selectivity of these products depended on the Lewis acids employed. For instance, ethyl coumalate was obtained from ethyl 3,3‐diethoxypropionate in high selectivity under the influence of d‐block Lewis acids like FeCl 3 , whereas triethyl 1,3,5‐benzenetricarboxylate was obtained in preference to ethyl coumalate under the influence of lanthanoid Lewis acids like GdCl 3 . Various coumalates were synthesized by the FeCl 3 ‐catalyzed cross‐cyclodimerization of acetals with active methylene compounds. From 4,4‐dimethoxy‐2‐butanone, however, 1,3,5‐triacetylbenzene, which is difficult to prepare regioselectively by conventional methods, was formed in quantitative yield under the influence of AlCl 3 . This reaction would provide a very convenient route to 1,3,5‐triacetylbenzene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)