Lewis base catalysis proved to be more efficient, and the highest asymmetric induction for allylation of ortho-fluorobenzaldehyde reached 82 % ee, which is comparable to other used catalytic conditions. In cases of ortho-vinylbenzaldehyde, the Keck allylation provided the product in 88 % ee. An enantioenriched homoallylicalcohol was used as the starting material for the synthesis of a sertraline
我们报告了在路易斯碱(N,N-二氧化物)、路易斯酸(凯克烯丙基化)和布朗斯台德酸催化下邻位取代苯甲醛烯丙基化的系统研究。邻-卤代苯甲醛被用作醛底物,并特别关注邻-乙烯基和炔基苯甲醛,它们可能作为有趣的合成子用于制备更复杂的手性化合物。在催化条件下实现了类似的对映选择性。在邻卤苯甲醛的情况下,路易斯碱催化被证明更有效,邻氟苯甲醛烯丙基化的最高不对称诱导达到 82% ee,与其他使用的催化条件相当。在邻乙烯基苯甲醛的情况下,Keck 烯丙基化提供 88% ee 的产物。
Stereoselective Synthesis of Cyclic Guanidines by Directed Diamination of Unactivated Alkenes
作者:Artur K. Mailyan、Kyle Young、Joanna L. Chen、Bradley T. Reid、Armen Zakarian
DOI:10.1021/acs.orglett.6b02778
日期:2016.11.4
method for a directed stereoselective guanidinylation of alkenes is described. The guanidine unit can be delivered as an intact fragment by a hydroxy or carboxy group, usually with a high level of stereocontrol. After the guanidine delivery, the directinggroup can be cleaved under exceptionally mild conditions, typically by alcoholysis in the presence of acetic acid. Broad functionalgroup tolerance
Palladium-catalyzed anti-Markovnikov oxidative acetalization of activated olefins with iron(<scp>iii</scp>) sulphate as the reoxidant
作者:Rodney A. Fernandes、Sandhya S. Yadav、Praveen Kumar
DOI:10.1039/d1ob02227j
日期:——
efficient palladium-catalyzed anti-Markovnikov oxidative acetalization of activated terminal olefins with iron(III) sulfate as the reoxidant. This methodology requires mild reaction conditions and shows high regioselectivity toward anti-Markovnikov products and compatibility with a wide range of functional groups. Iron(III) sulphate was the sole reoxidant used in this method. Various olefins like vinylarenes
本文公开了以硫酸铁( III )为再氧化剂的活性末端烯烃的高效钯催化抗马尔科夫尼科夫氧化缩醛化反应。该方法需要温和的反应条件,并显示出对抗马尔科夫尼科夫产物的高区域选择性以及与多种官能团的相容性。硫酸铁( III ) 是该方法中使用的唯一再氧化剂。各种烯烃,如乙烯基芳烃、芳基烯丙基醚、丙烯酸芳基或苄基丙烯酸酯和高烯丙醇都反应良好,提供抗马尔科夫尼科夫缩醛,其中一些代表正交官能化的 1,3-和 1,4-二氧化化合物。
Manganese-Mediated Carbon−Carbon Bond Formation in Aqueous Media: Chemoselective Allylation and Pinacol Coupling of Aryl Aldehydes
of manganese as a mediator for allylations and pinacol couplings in aqueousmedia was investigated. The combination of manganese and copper is found to be a highly effective mediator for the allylation of aryl aldehydes in water. Such a combination is found to be more reactive than other previously reported metals in aqueousmedia. No reaction was observed with either manganese or copper alone as the
Magnesium-Mediated Carbon−Carbon Bond Formation in Aqueous Media: Barbier−Grignard Allylation and Pinacol Coupling of Aldehydes
作者:Wen-Chun Zhang、Chao-Jun Li
DOI:10.1021/jo982497p
日期:1999.4.1
alkylation of aldehydes with alkyl halides was studied in aqueousmedia. The reaction of aromatic aldehydes with allyl halides is highly effective with either THF or water as the reaction solvent but poor in a mixture of THF/water. It was found that the magnesium-mediated allylation of aldehydes with allyl bromide and iodide proceeds effectively in aqueous 0.1 N HCl or 0.1 N NH(4)Cl. Aromatic aldehydes reacted
在含水介质中研究了镁介导的Barbier-Grignard型醛与烷基卤化物的烷基化反应。用THF或水作为反应溶剂,芳族醛与烯丙基卤的反应非常有效,但是在THF /水的混合物中效果较差。已经发现,镁与烯丙基溴和碘的醛介导的烯丙基化在0.1 N HCl或0.1 N NH(4)Cl水溶液中有效进行。芳族醛在脂肪族醛的存在下发生化学选择性反应。当脂族和芳族醛官能团同时存在于同一分子中时,也观察到排他选择性。在不存在烯丙基卤的情况下,醛和酮与镁在0.1 N NH(4)Cl水溶液中反应形成高产率的相应频哪醇偶联产物。频哪醇反应的有效性受到羰基周围空间环境的强烈影响。脂肪醛和简单的烷基卤化物在用于烷基化或频哪醇偶联反应的反应条件下呈惰性。