Tandem Cycloaddition Chemistry of 2-Azoniaheterodienes

说明书(由申请人提供)：本申请的基本目的是开发和应用两个2-偶氮杂二烯的串联[4+2]/[3+2]环加成反应，即硝基烯和N-乙烯基硝酮。该计划分为两个主要部分，虽然具体目标不同，但在制备天然和非天然杂环化合物的新反应化学的共同主题上是统一的。 与硝基烯烃有关的方法学目标分为两部分。第一个将涉及已建立的硝基烯的环加成化学的扩展，通过：(1)亲二烯变化(1-和2-烷氧基二烯)，(2)使用手性Lewis酸催化[4+2]过程和(3)研究经[3+2]环加成后加入更大环的改性偶极化合物。方法学研究的第二部分是Intra/Intra[4+2]/[3+2]串联环加成反应的探索和发展。这一新的转换家族将允许从简单的非环前体快速和选择性地构建复杂的多环环体系。一项主要的活动将是评估这一类中选定的排列的范围、生存能力和定型控制元素。 串联硝基烯烃环加成反应的合成目标包括一些生物碱家族的天然化合物。选择了斯堪地丁(一种小球藻生物碱)、UCS1025A/B(一种罕见的吡咯里西丁生物碱)和瑞香内酯(一种瑞香碱)，以突出不同串联工艺的战略力量。耐人寻味的新一类1-氮杂吩烷也将准备评估中心碳的扭曲。 提案的第二个主要部分是N-乙烯基硝酮的环加成化学的发明、开发和探索，N-乙烯基硝酮是一类新的2-偶氮杂二烯。这些杂化杂二烯/偶极化合物为合成哌啶类化合物和嵌入哌啶的多环化合物提供了巨大的潜力。将讨论制备、结构、稳定性、反应性(在[4+2]和[3+2]流形中)的基本特征，并特别注意与分子内连接组分的串联环加成反应中的机会。

DESCRIPTION (provided by applicant): The basic objectives of this application are the development and application of the tandem [4+2]/[3+2] cycloaddition reactions of two 2-azoniaheterodienes, the nitroalkene and N-vinylnitrone groups. The program is divided into two major sections with different specific aims but unified in the common theme of new reaction chemistry for the preparation of natural and non-natural heterocyclic compounds. The methodological objective relating to nitroalkenes is subdivided into two parts. The first will involve the expansion of the established cycloaddition chemistry of nitroalkenes to access different size rings through: (1) dienophile variation (1- and 2-alkoxydienes), (2) the use of chiral Lewis acid catalysis the [4+2] process and (3) and investigation of modified dipolarophiles to incorporate larger rings after [3+2] cycloaddition. The second part of the methodological study is the exploration and development of the intra/intra [4+2]/[3+2] tandem cycloadditions. This new family of transformations will allow for the rapid and selective construction of complex polycyclic ring systems from simple acyclic precursors. A major activity will be the assessment of scope, viability and stereocontrol elements in selected permutations of this class. Synthetic targets for the tandem nitroalkene cycloaddition include natural compounds in a number of alkaloid families. Scandine (a melodinus alkaloid) UCS1025A/B (a rare pyrrolizidine alkaloid) and daphnilactone (a daphniphyllum alkaloid) are chosen to highlight the strategic power of different tandem processes. The intriguing new class of 1-azafenestranes will also be prepared to assess the distortion of the central carbon. The second major section of the proposal is the invention, development and exploration of the cycloaddition chemistry of N-vinylnitrones, a new family of 2-azoniaheterodienes. These hybrid heterodiene/dipoles offer great potential for the general synthesis of piperidines and piperidine-embedded polycyclic compounds. The basic features of preparation, structure, stability, reactivity (in both [4+2] and [3+2] manifolds) will be addressed with particular attention to opportunities in tandem cycloadditions with intramolecularly tethered components.