Stereoselective alkenylation of aldehydes with phosphorus carbanions: Preparation of E- and Z-2-alkoxy- and 2-aryloxy-2-alkenoates
Stereoselective alkenylation of aldehydes with phosphorus carbanions: Preparation of E- and Z-2-alkoxy- and 2-aryloxy-2-alkenoates
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DOI：
10.1016/s0040-4020(97)10149-1
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发表时间：
1997-12-15
期刊：
影响因子：
2.1
通讯作者：
Nadler, G
中科院分区：
文献类型：
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作者：
Seneci, P;Leger, I;Nadler, G
合成了18个磷基烷基化试剂1a-6c，并与正丁醛7a和苯甲醛7f缩合。它们与醛7b-e，g-n缩合生成2-甲氧基-2-烯酸酯8a-n和2-苯氧基-2-烯酸酯9a-n。讨论了不同实验条件(碱、碱、温度)下烷基化试剂的不同选择性，醛对几何产物(富电子取代基或贫取代基空间位阻)的影响，以及每类醛最大E和Z选择性反应条件的选择，即在THF中与DBU反应时，三苯基膦盐La具有较好的Z选择性，而在THF中与KN(SiMe3)(2)在-78度时，三氟乙基膦盐5b、6b和6c对E-选择性较好。(C)1997年爱思唯尔科学有限公司。
Eighteen phosphorus-based alkerrylation reagents 1a-6c were synthesized and condensed with n-butyraldehyde 7a and benzaldehyde 7f. They were condensed with the aldehydes 7b-e,g-n to produce 2-methoxy-2-alkenoates 8a-n and 2-phenoxy-2-alkenoates 9a-n. A discussion on different selectivities for the alkerrylation reagents under different experimental conditions (base, soh em, temperature), the influence of the aldehydes on the geometrical outcome (electron rich or poor substituents steric hindrance) and the selection of the most E-and Z-selective reaction conditions for each class of aldehydes are reported Namely, triphenyl phosphonium salt la at RT in THF with DBU was better for Z-selectivity while trifluoroethylphosphonates 5b, 6b and 6c at -78 degrees in THF with KN(SiMe3)(2) were better for E-selectivity. (C) 1997 Elsevier Science Ltd.