Synthetic Routes to Allenic Acids and Esters and Their Stereospecific Conversion to Butenolides
作者:James A. Marshall、Mark A. Wolf、Eli M. Wallace
DOI:10.1021/jo9618740
日期:1997.1.1
19 and 23 with inversion of configuration through treatment with Pd(Ph(3)P)(4), CO, and the appropriate alcohol in THF. These reactions proceeded with ca. 10% or less of racemization. The allenic esters 23 yielded the iodobutenolides 24 by reaction with IBr. Hydrogenolysis to the butenolide 25 was achieved with Pd(PPh(3))(4) and Bu(3)SnH. Alternatively, the allenic acids 27 could be prepared directly
已详细研究了烯丙酸和酯的合成及其向丁烯内酯的转化。外消旋的丁烯内酯10可通过用BCl(3)处理并将酯酸9暴露于催化的AgNO(3)在丙酮中的酯8高效地制备。通过锂化和随后用CO(2)羧化将对映体富集的烯丙基锡烷(S)-17转化为酸18,得到外消旋产物。通过用Pd(Ph(3)P)(4),CO和适当的醇在THF中处理,富含对映体的炔丙基甲磺酸酯16和22提供了烯丙基酯19和23,其构型转化。这些反应进行了约。外消旋化的10%或更少。烯丙酸酯23通过与IBr反应产生碘代丁烯内酯24。用Pd(PPh(3))(4)和Bu(3)SnH实现对丁烯内酯25的氢解反应。备选地,可以从甲磺酸盐22与Pd(PPh(3))(4)和CO在THF水溶液中直接制备烯丙酸27。如前所述,通过催化AgNO(3)实现了对丁烯内酯25的环化。