Lewis Acid‐Catalyzed Intramolecular [3+2] Cross‐Cycloaddition of Aziridine 2,2‐Diesters with Conjugated Dienes for Construction of Aza‐[n.2.1] Skeletons

Abstract

A novel Lewis acid-catalyzed [3+2] intramolecular cross-cycloaddition (IMCC) between aziridine 2,2-diesters and conjugated dienes has been developed. This is the first regiospecific IMCC of intramolecular 1,3-dipolar cycloadditions of azomethine ylides with carbon=carbon double bonds, and supplies a general and efficient strategy for construction of structurally complex and diverse aza-[n.2.1] skeletons. The [3+2]IMCC could be carried out under mild conditions and in gram scale. More importantly, 3-alkyl-substituted aziridines were also successful. The excellent structural diversity, the facile operation and the versatile post-modifications will support the applications of the [3+2]IMCC in natural products synthesis and drugs discovery.

Synthetic Approaches to Non-Tropane, Bridged, Azapolycyclic Ring Systems Containing Seven-Membered Carbocycles

“…50 Similarly, appropri-ately substituted aziridines can serve as precursors to azomethine ylides, which can then participate in [3+2] cycloadditions. Wang 51 showed that tosylaziridine 166 (Scheme 32), in which the dipolarophile is part of a conjugated diene, underwent a regioselective intramolecular cycloaddition to give the bridged 7-azabicyclo[4.2.1]nonane system 167 (as opposed to the fused system) upon exposure to a substoichiometric amount of SnCl 4 .…”

Methods and Strategies for the Synthesis of Peduncularine

“…第二种方式为分子内 Mannich 反应(C) [55] 形成 C(4)-C(5)键. 第三种方式为同 时形成 C(3)-C(4)及 C(1)-C(8)键, 例如新颖的氮丙 啶 -共 轭 二 烯 化 合 物 分 子 内 [3 ＋ 2] 交 叉 环 加 成 反 应 (D) [56] . 第四种方式为 C(5)-N 键的形成, 由于处于桥环 连接处, 并且涉及碳杂原子键的形成, 合成策略较多.…”

Polyhalogenated 2‐Azabicyclo[2.2.1]heptanes from Polyhaloaldimines and Cyclopentadiene via Cycloaddition and Wagner‐Meerwein Rearrangement

“…In continuation of our ongoing research into the reactivity of substituted azabicycloheptenes, in the present work we studied the bromination and chlorination of 2‐(arylsulfonylaza)‐3‐(polychloromethyl)bicyclo[ 2.2.1 ]hept‐5‐enes 9 , 10 a – c synthesized by the reaction of highly electrophilic polychloroaldimines 7 , 8 a – c with cyclopentadiene (Table 1). Our endeavors were motivated by the fact that further substitution or elimination of halogen atoms involving the expected halogenation products open new avenues for the synthesis of functionalized azanorbornanes, azanorbornenes and their derivatives, the analogs of which are valuable reagents and promising biologically active substances [41–44] . For the first time, the features of bromination of 2‐azanorbornenes were demonstrated by Raasch [45] .…”

“…Our endeavors were motivated by the fact that further substitution or elimination of halogen atoms involving the expected halogenation products open new avenues for the synthesis of functionalized azanorbornanes, azanorbornenes and their derivatives, the analogs of which are valuable reagents and promising biologically active substances. [41][42][43][44] For the first time, the features of bromination of 2-azanorbornenes were demonstrated by Raasch. [45] In this pioneering work, 2-(arylsulfonylaza)bicyclo[2.2.1]hept-5-enes were represented by only two examples -cycloadducts derived from tosylchloralimine and tosylimine of glyoxylic acid.…”