Solid-Phase Synthesis of Monocyclic β-Lactam Derivatives
摘要:
Liquid-phase studies concerning the solid-phase synthesis of monocyclic beta-lactams via the esterenolate imine condensation route have been conducted utilizing triazene esters 1 and 2 as model compounds. Esters were attached to benzylamine resin 6 by a triazene linker employing the respective diazonium salts. Immobilized ester-enolates 8 and 10 were reacted with various imines and imine precursors to give polymer-bound beta-lactams 14 and 17 in different substitution patterns. Traceless cleavage from the triazene linker yields the desired beta-lactams 16 and 19.
Evolution of the Total Syntheses of Ustiloxin Natural Products and Their Analogues
作者:Pixu Li、Cory D. Evans、Yongzhong Wu、Bin Cao、Ernest Hamel、Madeleine M. Joullié
DOI:10.1021/ja710363p
日期:2008.2.1
synthetically challenging chiral tertiary alkyl-aryl ether linkage. The first total synthesis of ustiloxin D was achieved in 31 linear steps using an S(N)Ar reaction. An NOE study of this synthetic product showed that ustiloxin D existed as a single atropisomer. Subsequently, highly concise and convergent syntheses of ustiloxins D and F were developed by utilizing a newly discovered ethynyl aziridine ring-opening
Ustiloxins AF 是抗有丝分裂杂环肽,含有 13 元环状核心结构,具有合成上具有挑战性的手性叔烷基芳基醚键。使用 S(N)Ar 反应,通过 31 个线性步骤实现了 ustiloxin D 的首次全合成。该合成产品的 NOE 研究表明乌司洛辛 D 作为单一阻转异构体存在。随后,利用新发现的乙炔基氮丙啶开环反应,以 15 个步骤的最长线性序列开发了乌斯蒂洛辛 D 和 F 的高度简洁和收敛的合成方法。该方法进一步优化以实现更好的大环内酰胺化策略。通过第二代制备了乌斯蒂洛辛D、F和8个类似物(14-MeO-乌斯蒂洛辛D、4个C-6位氨基酸残基不同的类似物、以及3个(9R,10S)-表乌斯蒂洛辛类似物)路线。对这些化合物作为微管蛋白聚合抑制剂的评估表明,C-6 位的变化在一定程度上是可以容忍的。相反,C-9 甲氨基的 S 构型和游离酚羟基对于抑制微管蛋白聚合至关重要。
Indirect electrochemical α-methoxylation of -acyl and -carboalkoxy α-amino acid esters and application as cationic glycine equivalents
Indirect electrochemical methoxylation of -acyl and -carboalkoxy α-aminoacidesters in α-position to nitrogen is possible, if chloride is used as mediator. The course of the reaction depends upon the protecting group as well as upon the amino acid side-chain. Increased electron withdrawing effects of the protecting group are accelerating the reaction. On the other hand aliphatic side-chains are diminishing
作者:Jialin Xie、Yuanqiong Huang、Hongjian Song、Yuxiu Liu、Qingmin Wang
DOI:10.1021/acs.orglett.7b02767
日期:2017.11.17
An atom-economical method for accessing tetrasubstituted 4,5-biscarbonylimidazoles by reaction between glycine derivatives and 5-alkoxyoxazoles is reported. The method, which involves a copper-catalyzedaerobic oxidative [2 + 3] cyclization/aromatization cascade process, starts from readily available and inexpensive materials, uses molecular oxygen as a co-oxidant, and has a broad substrate scope.
Iron-Catalyzed Efficient Synthesis of Amides from Aldehydes and Amine Hydrochloride Salts
作者:Subhash Chandra Ghosh、Joyce S. Y. Ngiam、Christina L. L. Chai、Abdul M. Seayad、Tuan Thanh Dang、Anqi Chen
DOI:10.1002/adsc.201200020
日期:2012.5.21
A practical and efficient method for the synthesis of amides has been developed by iron‐catalysed oxidative amidation of aldehydes with aminehydrochloridesalts. A wide range of amides have been obtained in good to excellent yields under mild conditions. The application of this novel amide formation reaction to the synthesis of pharmaceutical compounds has been successfully demonstrated.
Palladium-catalyzed aerobic oxidative aminocarbonylation and alkoxycarbonylation reactions with aryl hydrazines as coupling partners have been developed. The oxidative carbonylation of aryl hydrazines proceeded smoothly at atmospheric pressure CO, employing molecular oxygen as the terminal oxidant. The only byproducts were nitrogen gas and water for both reactions. Notably, no double carbonylation