Diverse Applications of Nitrones for the Synthesis of Heterocyclic Compounds
Diverse Applications of Nitrones for the Synthesis of Heterocyclic Compounds
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DOI：
10.1002/ajoc.201500211
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发表时间：
2016-02
影响因子：
2.7
通讯作者：
Laura L. Anderson
中科院分区：
文献类型：
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作者：
Laura L. Anderson
虽然硝酮最为人所知的是它们的[3+2]-偶极环加成反应性和在异恶唑啉和异恶唑烷的制备中的用途，但硝酮是多用途试剂，其经历各种转化以合成各种杂环化合物。用硝酮试剂合成杂环的范围包括：1）硝酮与重氮乙酸乙烯酯、过渡金属配位的环异构化中间体、三亚甲基甲烷和环丙烷二酯的逐步[3+3]-环加成反应，生成二氢和四氢-1，2-恶嗪; 2）炔系硝酮的内部氧化还原环化反应，以提供获得氮杂双环辛烷、异吲哚、氨基茚满酮和异喹诺酮的途径; 3）原位生成的N-丙二烯基硝酮的电环化以形成吡啶和氮杂环丁烷-N-氧化物，以及硝酮的金属催化的环化和重排以形成氮杂卓-N-氧化物、螺环异恶唑啉和α，β-环氧亚胺;以及4）硝酮的[3+2]-环加成反应的使用以触发级联反应以形成四氢氧氮杂卓、二氢咔唑和苯并吲嗪。本焦点综述旨在突出硝酮在杂环化合物合成中的各种应用，以强调这些活性中间体的广泛用途，并激发其作为重要的硝酮的进一步发展，超越传统的[3+2]-偶极环加成反应的范围。
Although best known for their [3+2]-dipolar cycloaddition reactivity and use in the preparation of isoxazolines and isoxazolidines, nitrones are versatile reagents that undergo a variety of transformations for the synthesis of a diverse array of heterocyclic compounds. The breadth of heterocycle synthesis using nitrone reagents includes: 1) stepwise [3+3]-cycloaddition reactions of nitrones with vinyl diazoacetates, transition-metal-coordinated cycloisomerization intermediates, trimethylene methanes, and cyclopropane diesters to form dihydro- and tetrahydro-1,2-oxazines; 2) internal redox cyclization reactions of alkyne-tethered nitrones to provide access to azabicyclooctanes, isoindoles, aminoindanones, and isoquinolones; 3) electrocyclizations of in situ generated N-allenylnitrones to form pyridines and azetidine-N-oxides, as well as metal-catalyzed cyclizations and rearrangements of nitrones to form azepine-N-oxides, spirocyclic isoxazolines, and α,β-epoxyimines; and 4) the use of [3+2]-cycloaddition reactions of nitrones to trigger cascade reactions for the formation of tetrahydrooxazepines, dihydrocarbazoles, and benzoindolizines. This Focus Review aims to highlight these diverse applications of nitrones for the synthesis of heterocycles to emphasize the broad utility of these reactive intermediates and to inspire their further development as important synthons beyond the scope of traditional [3+2]-dipolar cycloaddition reactions.