Organics Pub Date : 2024-07-05 DOI: 10.3390/org5030010

G. Breton, Jazmine V. Ridlehoover

{"title":"Spontaneous Formation of Strained Anti-Bredt Bridgehead Alkenes upon Computational GeometryOptimization of Bicyclic β-Halo Carbanions","authors":"G. Breton, Jazmine V. Ridlehoover","doi":"10.3390/org5030010","DOIUrl":"https://doi.org/10.3390/org5030010","url":null,"abstract":"Bridgehead alkenes are polycyclic molecules bearing at least one C=C bond that includes a bridgehead carbon atom. For small bicyclic systems, these bonds are highly strained due to geometric constraints placed on the sp2 hybridized carbon atoms. These small, strained molecules have been termed “anti-Bredt” alkenes. β-halo carbanions have served as convenient precursors to bridgehead alkenes in experimental studies. We observed that upon attempted computational geometric optimizations (ωB97X-D/aug-cc-pVDZ) of the precursors, spontaneous elimination of the halide occurs along with formation of the anti-Bredt alkene in many cases. Such computational eliminations were shown to faithfully mimic experimentally obtained results. Computational elimination was not observed for [1.1.1] or [2.1.1] frameworks, in agreement with predictions that these bridgehead alkenes are too strained to be formed. However, computational elimination from the [2.2.1] framework was observed to form 1-norbornene, a compound suggested in experimental work to be a reactive intermediate. Similarly, [3.1.1] frameworks and higher led to eliminations upon computational geometric optimization, in agreement with experimental findings. Natural bond order (NBO) calculations of the starting geometries proved to be excellent predictors as to whether elimination would take place. Those precursor compounds exhibiting delocalization energies in the order of 10 kcal/mol between the lone-pair electrons of the carbon atom and σ*C-Br were generally found to undergo elimination. Thus, computational optimization of β-halo substituted bicyclic precursor anions can be used to predict whether strained anti-Bredt alkenes are likely to be formed, thereby saving valuable time and costs in the experimental lab.","PeriodicalId":509081,"journal":{"name":"Organics","volume":"156 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141674196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Chiral Nonaromatic Nitrogen-Heterocycles by Asymmetric Intramolecular Haloamination and Haloamidation 通过不对称分子内卤化和卤酰胺化反应制备手性非芳香族氮杂环

Organics Pub Date : 2024-07-02 DOI: 10.3390/org5030009

M. Orena, S. Rinaldi

引用次数: 0

Synthesis of Novel Trisubstituted Olefin-Type Probe Molecules Containing N-Heterocycles and Their Application in Detection of Malononitrile 含 N-杂环的新型三取代烯烃类探针分子的合成及其在检测丙二腈中的应用

Organics Pub Date : 2024-04-02 DOI: 10.3390/org5020004

Zhao-Hua Chen, Shijin Yu, Wen-Jin Xu, Miao-Xin Li, Yong Zeng, Si-Wei Deng, Jian-Yun Lin, Zhao-Yang Wang

{"title":"Synthesis of Novel Trisubstituted Olefin-Type Probe Molecules Containing N-Heterocycles and Their Application in Detection of Malononitrile","authors":"Zhao-Hua Chen, Shijin Yu, Wen-Jin Xu, Miao-Xin Li, Yong Zeng, Si-Wei Deng, Jian-Yun Lin, Zhao-Yang Wang","doi":"10.3390/org5020004","DOIUrl":"https://doi.org/10.3390/org5020004","url":null,"abstract":"Recently, the construction of the trisubstituted olefin-type probe molecules has elicited the attention of many researchers. However, the synthesis of the trisubstituted olefin-type probes containing two N-heterocycles simultaneously has been rarely reported. In this study, starting from the inexpensive mucobromic acid 1 and N-heterocyclic compound 2, we first utilized a simple one-step reaction to synthesize a series of trisubstituted olefin-type compounds 3 simultaneously bearing with the structure of two N-heterocyclic rings in the absence of transition metal catalysts with a yield of 62–86%. The optimal reaction conditions were systematically explored, and the structure of the obtained compounds 3 were well characterized with 1H NMR, 13C NMR, X-ray single-crystal and HR-MS. The preliminary observation showed that, in the presence of base, mucobromic acid 1 reacts as its ring-opening structure, and the successive nucleophilic substitution reaction and Michael addition reaction can generate the target product 3. Considering that the aldehyde group in the molecular structure of the trisubstituted olefin-type compounds 3 may react with malononitrile, we carried out some relevant investigations so as to realize the visual detection of malononitrile. Interestingly, among the products, compounds 3a–3c can be prepared in portable test strips through a simple process and used to achieve the naked-eye detection of malononitrile in environmental systems as designed.","PeriodicalId":509081,"journal":{"name":"Organics","volume":"94 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140751666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Synthesis and Butyllithium-Induced Cyclisation of 2-Benzyloxyphenylphosphonamidates Giving 2,3-Dihydrobenzo[d][1,3]oxaphospholes 生成 2,3-二氢苯并[d][1,3]氧磷烯的 2-苄氧基苯基膦酰胺酸盐的合成和丁锂诱导的环化反应

Organics Pub Date : 2024-02-01 DOI: 10.3390/org5010002

R. A. Aitken, Khadija Ait Moulay, David B. Cordes, Ryan A. Inwood, Fraser G. Jamieson, Alexander J. B. Nelson, Aidan P. McKay

引用次数: 0

How an Internal Supramolecular Interaction Determines the Stereochemistry of a Metal Center 超分子内部相互作用如何决定金属中心的立体化学性质

Organics Pub Date : 2024-01-04 DOI: 10.3390/org5010001

Maxime Steinmetz, C. Gourlaouen, David Sémeril

引用次数: 0

Synthesis of 2-Substituted Benzimidazole Derivatives as a Platform for the Development of UV Filters and Radical Scavengers in Sunscreens 合成 2-取代的苯并咪唑衍生物，作为开发防晒霜中紫外线过滤剂和自由基清除剂的平台

Organics Pub Date : 2023-11-28 DOI: 10.3390/org4040036

K. Anichina, Nikolai I. Georgiev

引用次数: 0

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