tert-Butyl (RS)-3-methoxy- and (RS)-3-tert-butyldiphenylsilyloxy-cyclopent-1-ene-carboxylates display excellent levels of enantiorecognition in mutual kinetic resolutions with both lithium (RS)-N-benzyl-N-(α-methylbenzyl)amide and lithium (RS)-N-3,4-dimethoxybenzyl-N-(α-methylbenzyl)amide. A 50 : 50 pseudoenantiomeric mixture of lithium (S)-N-benzyl-N-(α-methylbenzyl)amide and lithium (R)-N-3,4-dimethoxybenzyl-N-(α-methylbenzyl)amide allows for the efficient parallel kinetic resolution of the tert-butyl (RS)-3-oxy-substituted cyclopent-1-ene-carboxylates, affording differentially protected 3-oxy-substituted cispentacin derivatives in high yield and >98% de. Subsequent N-deprotection and hydrolysis provides access to 3-oxy-substituted cispentacin derivatives in good yield, and in >98% de and >98% ee, while stereoselective epimerisation and subsequent deprotection affords the corresponding transpentacin analogues in good yield, and in >98% de and >98% ee.
(RS)-3-甲氧基-和(RS)-3-叔丁基二苯基
硅氧基-
环戊烯-1-
羧酸叔丁酯在与(RS)-N-苄基-N-(α-甲基苄基)酰胺
锂和(RS)-N-3,4-二甲氧基苄基-N-(α-甲基苄基)酰胺
锂的相互动力学解析中显示出极佳的对映体识别
水平。A 50 :(S)-N-苄基-N-(α-甲基苄基)酰胺
锂和(R)-N-3,4-二甲氧基苄基-N-(α-甲基苄基)酰胺
锂的 50 : 50 假对映异构体混合物可以高效地平行动力学解析叔丁基 (RS)-3- 氧代环戊-1-烯-
羧酸酯,得到不同保护的 3-氧代西喷他辛衍
生物,产率高、de>98%。随后进行 N-脱保护和
水解,可获得 3-氧代双
香豆素衍
生物,收率高,de 和 ee 分别大于 98% 和 98%,而立体选择性外二聚化和随后的脱保护则可获得相应的换位
香豆素类似物,收率高,de 和 ee 分别大于 98% 和 98%。