N‐alkoxy group played important roles in this reaction. First, it removed the requirement for an extra preactivation step prior to nucleophilic addition to activate inert amide carbonyl groups. Second, the N‐alkoxy group formed a five‐membered chelated complex after the firstnucleophilic addition, resulting in suppression of an extra addition of the firstnucleophile. While diisobutylaluminum hydride (DIBAL‐H)
Anti-Markovnikov Addition of Both Primary and Secondary Amines to Terminal Alkynes Catalyzed by the TpRh(C<sub>2</sub>H<sub>4</sub>)<sub>2</sub>/PPh<sub>3</sub> System
Terminal alkynes react with secondaryamines in the presence of TpRh(C2H4)2/PPh3 (Tp = trispyrazolylborate) to give anti-Markovnikov E-enamines. Both Tp and PPh3 ligands are essential for the reaction. The reaction tolerates functional groups, such as ester, nitrile, and siloxy groups, on the terminal alkynes. Primaryamines also add to terminal alkynes in anti-Markovnikov fashion, yielding the corresponding
catalytic system is applicable to the N-alkylation of both primary and secondary amines, and only harmless water is produced as co-product. A wide variety of secondary and tertiary amines can be synthesized with high atom economy under mild and less-toxic conditions. One-pot sequential N-alkylation leading to tertiary amines bearing three different substituents is also described.
High-Throughput Screening of Reductive Amination Reactions Using Desorption Electrospray Ionization Mass Spectrometry
作者:David L. Logsdon、Yangjie Li、Tiago Jose Paschoal Sobreira、Christina R. Ferreira、David H. Thompson、R. Graham Cooks
DOI:10.1021/acs.oprd.0c00230
日期:2020.9.18
screening system that is capable of screening thousands of organicreactions in a single day. This system combines a liquid handling robot with desorption electrospray ionization (DESI) mass spectrometry (MS) for a rapid reaction mixture preparation, accelerated synthesis, and automated MS analysis. A total of 3840 unique reductive amination reactions were screened to demonstrate the throughputs that are
the N‐alkylation of ammonia (or its surrogates) and amines with “primary” alcohols. On the other hand, the N‐alkylation of ammonia surrogates (i.e., urea and NH4HCO3) with “secondary” alcoholsselectively produced the corresponding symmetrically substituted “secondary” amines, even in the presence of excess amounts of alcohols, which is likely due to the steric hindrance of the secondary alcohols and/or
易于制备的厌氧条件下,可以有效地促进氨(或其替代物,如尿素,NH 4 HCO 3和(NH 4)2 CO 3)和胺与醇(包括伯醇和仲醇)的N-烷基化反应。廉价的负载型氢氧化钌催化剂Ru(OH)x / TiO 2。氨(或其替代物)和胺与“伯”醇的N烷基化反应可以合成各种类型的对称和不对称取代的“叔”胺。另一方面,氨代用品(即尿素和NH 4)的N烷基化HCO 3)与“仲”醇选择性地产生相应的对称取代的“仲”胺,即使在存在过量的醇的情况下,这很可能是由于所产生的仲醇和/或仲胺的空间位阻所致。在有氧条件下,腈可以直接由醇和代理氨合成。观察到的当前N烷基化反应的催化本质上是非均相的,并且回收的催化剂可以重复使用而不会显着降低催化性能。当前的催化转化将通过连续N次进行烷基化反应,其中醇充当烷基化试剂。根据氘标记实验,建议在N烷基化反应期间形成二氢化钌。