Rhodium-Katalysierte Isomerisierungen von 2-Methylidenglutarsäureestern zu Methylglutaconsäureestern
作者:Claus D. Weis、Tammo Winkler
DOI:10.1002/hlca.19740570343
日期:1974.4.27
The Rhodium(III)-catalyzed thermal isomerization of 2-methylidenglutaric acid esters affords predominantly mixtures of cis/trans-2-methylglutaconic acid esters (2, 3) which upon slow distillation isomerize completely into the cis-esters (2). Saponification of 2 yields trans-2-methylglutaconic acid (5). Attempts to prepare the acid chloride of 5 produces 6-chloro-5-methylpyrone-2 (9) or 6-chloro-3-methylpyrone-2
铑(III)催化的2-甲基亚甲基戊二酸酯的热异构化主要提供了顺式/反式-2-甲基戊二酸酯的混合物(2,3),在缓慢蒸馏后会完全异构化成顺式酯(2)。2的皂化产生反式-2-甲基谷氨酸(5)。尝试制备5的酰氯会生成6-氯-5-甲基吡喃酮2(9)或6-氯-3-甲基吡喃酮2(10),它们与苯胺反应生成反式-4-甲基谷氨酸的N-取代衍生物酰胺(11)。根据它们的酯烯醇结构中的1,5-氢转移来讨论各个酯的热异构化。