trans counterpart, the cis-configured scaffold derived from the Castagnoli–Cushman reaction (CCR) is scarce and has not been explored in bioactive compound design. We found that conducting this reaction in DMF (in contrast to conventional toluene or xylene) led to a significantly higher proportion of cis-configured lactams in the diastereomeric product mixture. This allowed us, for the first time, to obtain
与它的反式对应物不同,源自Castagnoli-Cushman反应(CCR)的顺式构型支架十分稀少,尚未在生物活性化合物设计中进行探索。我们发现,在DMF中进行该反应(与常规的甲苯或二甲苯相反)导致非对映体产物混合物中的顺式构型内酰胺的比例明显更高。这使我们第一次获得并充分表征了大量铅样CCR内酰胺的两种立体异构体。已经设计了基于1 H NMR的立体化学分配的简单规则,并将其与为纯顺式和反式获得的单晶X射线结构相关-配置的内酰胺。
1,1′-Carbonyldiimidazole as a cyclodehydrating agent for the Castagnoli–Cushman reaction of dicarboxylic acids and imines
作者:Evgeny G. Chupakhin、Olga Yu. Bakulina、Dmitry V. Dar’in、Mikhail Krasavin
DOI:10.1016/j.mencom.2019.05.016
日期:2019.5
A novel protocol for the Castagnoli-Cushman reaction of dicarboxylic acids and imines comprises the use of 1,1'-carbonyldiimidazole as the cyclodehydrating agent to in situ produce the intermediate anhydrides. In contrast to previously developed procedure involving the use of acetic anhydride, the current protocol allows one to utilize substrates prone to acylation or acid-promoted transformations, which significantly broadens the reaction scope of lactams to be obtained.
Highly Diastereoselective Synthesis of β-Carboxy-γ-lactams and Their Ethyl Esters via Sc(OTf)<sub>3</sub>-Catalyzed Imino Mukaiyama-Aldol Type Reaction of 2,5-Bis(trimethylsilyloxy)furan with Imines
Functionalized γ-lactams are found to be crucial intermediates in the synthesis of biologically important natural products. We herein described a highly diastereoselective synthesis of β-carboxy-γ-lactams and their ethyl ester derivatives, in high yields with high diastereomeric ratio, via the Mukaiyama-aldol type reaction of 2,5-bis(trimethysilyloxy)furan with imines, employing Sc(OTf)3 as a catalyst.