Regio- and stereoselective nickel-catalyzed homoallylation of aldehydes with 1,3-dienes
Regio- and stereoselective nickel-catalyzed homoallylation of aldehydes with 1,3-dienes
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DOI：
10.1021/ja0608904
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发表时间：
2006-07-05
影响因子：
15
通讯作者：
Tamaru, Yoshinao
中科院分区：
文献类型：
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作者：
Kimura, Masanari;Ezoe, Akihiro;Tamaru, Yoshinao
Ni（acac）（2）催化醛与1，3-二烯在三乙基硼烷存在下的均烯丙基化反应。三乙基硼烷用作还原剂，将甲醛氢化物递送到1，3-二烯的C2位置，从而产生甲醛高烯丙基阴离子物质并使醛的新型高烯丙基化成为可能。该反应在室温下在不存在任何膦或氮配体的情况下顺利进行，并且对于醛和1，3-二烯的各种组合具有高度的区域选择性和立体选择性：例如，在一个实施例中，将异戊二烯和苯甲醛联合收割机以90%的产率以15：1的比例混合得到反式-和顺式-1-苯基-3-甲基-4-戊烯-1-醇（2.2）。在此条件下，空间拥挤的脂肪醛和酮的产率较低。在这种情况下，二乙基锌用作三乙基硼烷的替代物，并以良好的产率以类似的高区域选择性和立体选择性产生预期的产物。1，3-环己二烯是24种二烯中的一个例外，它选择性地进行烯丙基化（而不是均烯丙基化）。
Ni(acac)(2) catalyzes homoallylation of aldehydes with 1,3-dienes in the presence of triethylborane. Triethylborane serves as a reducing agent delivering a formal hydride to the C2 position of 1,3-dienes, thus generating a formal homoallyl anion species and enabling the novel homoallylation of aldehydes. The reaction proceeds smoothly at room temperature in the absence of any phosphane or nitrogen ligands and is highly regioselective and stereoselective for a wide variety combination of aldehydes and 1,3-dienes: e. g., isoprene and benzaldehyde combine to give a mixture of anti- and syn-1-phenyl-3-methyl-4-penten-1-ol (2.2) in a ratio of 15:1 in 90% yield. Under the conditions, sterically congested aliphatic aldehydes and ketones show low yields. In such cases, diethylzinc serves as a substitute for triethylborane and yields the expected products in good yields with similarly high regio- and stereoselectivity. 1,3-Cyclohexadiene is one exception among 24 kinds of dienes examined and undergoes allylation (not homoallylation) selectively.