Stereoselective preparation of (E)-α-bromoacrylates from mixtures of brominated ando phosphonates
Stereoselective preparation of (E)-α-bromoacrylates from mixtures of brominated ando phosphonates
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DOI：
10.1055/s-2004-831166
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发表时间：
2004-09-06
影响因子：
2.6
通讯作者：
Brückner, R
中科院分区：
文献类型：
--
作者：
Olpp, T;Brückner, R
我们制备了69：31-11：89的膦酸酯6 b和7 b的混合物，其在散布的亚甲基上分别含有两个苯氧基取代基、一个CO2 Et基团和1或2个溴原子。将这些试剂与NaH的64：36混合物去质子化，并在0 ℃下加入各种醛，得到不饱和α-溴代酯。产率通常为70-99%，E-选择性（即酯和β-取代基顺式）为80：20-98：2。类似地，我们经由氯化膦酸酯49进行至不饱和α-氯代酯51，其中E：Z = 94：6（80%）。
We prepared 69:31-11:89 mixtures of phosphonates 6b and 7b containing two phenoxy substituents, a CO2 Et group, and 1 or 2 bromine atoms, respectively, at the interspersed methylene group. Deprotonating 64:36 mixtures of these reagents with NaH and adding a variety of aldehydes at 0 degreesC provided unsaturated alpha-bromoesters. Yields were typically 70-99% and E-selectivities (i.e. ester and beta-substituent cis) 80:20-98:2. Similarly, we proceeded via the chlorinated phosphonate 49 to the unsaturated alpha-chloroester 51 with E:Z = 94:6 (80%).