Highly stereoselective and efficient synthesis of ω-heterofunctional di- and trienoic esters for Horner–Wadsworth–Emmons reaction via alkyne hydrozirconation and Pd-catalyzed alkenylation
作者:Guangwei Wang、Zhihong Huang、Ei-ichi Negishi
DOI:10.1016/j.tetlet.2009.02.023
日期:2009.7
(E)-BrCHCHCO2Et and (E)-BrCHC(Me)CO2Et using PEPPSI-IPr (7) as a catalyst provides a highly efficient and selective (⩾98% all-E) route to ω-hydroxy di- and trienoic acid esters (1a–6a). The corresponding phosphonate esters (1c–4c) of ⩾98% isomeric purity can be obtained via conventional bromination–phosphonation in >80% yields. As expected, their carbonyl olefination is ca. 85–90% E-selective with alkyl aldehydes
用i Bu 2 AlH原位OH金属化并用HOCH 2 CCH,(E)-HOCH 2 CHCHCCH和HOCH 2 CCCH 3的HZrCp 2 Cl加氢锆化,然后用Pd催化的(E)-BrCHCHCO 2 Et偶联的烯基-烯基和(PE)-BrCHC(Me)CO 2 Et(使用PEPPSI-IPr(7)作为催化剂)提供了高效且选择性的(⩾98%all- E)途径制备ω-羟基二和三烯酸酯(1a – 6a)。相应的膦酸酯(1c –可以通过常规的溴化-膦酰化反应以> 80%的收率获得%98%的异构体纯度4c)。如所预期的,它们的羰基烯化为约。在所使用的条件下,烷基醛对E的选择性为85–90%,而PhCHO和某些α,β-不饱和醛对电子的选择性为⩾98%。