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Huang Z, Zhan M, Zhang S, Luo Q, Zhang WX, Xi Z. Synthesis of dibromo- and tetrabromo-bipyrrolines and their corresponding 2,6-diazasemibullvalene derivatives. Org Chem Front 2017. [DOI: 10.1039/c7qo00287d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Treatment of Δ1-dipyrrolines with NBS afforded α,α′-dibromo-Δ1-bipyrrolines and α,α,α′,α′-tetrabromo-Δ1-bipyrrolines, which were efficiently transformed into 2,6-diazasemibullvalene derivatives via reduction with lithium.
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Affiliation(s)
- Zhe Huang
- Beijing National Laboratory for Molecular Sciences (BNLMS)
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education
- College of Chemistry
- Peking University
- Beijing 100871
| | - Ming Zhan
- Beijing National Laboratory for Molecular Sciences (BNLMS)
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education
- College of Chemistry
- Peking University
- Beijing 100871
| | - Shaoguang Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS)
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education
- College of Chemistry
- Peking University
- Beijing 100871
| | - Qian Luo
- Beijing National Laboratory for Molecular Sciences (BNLMS)
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education
- College of Chemistry
- Peking University
- Beijing 100871
| | - Wen-Xiong Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS)
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education
- College of Chemistry
- Peking University
- Beijing 100871
| | - Zhenfeng Xi
- Beijing National Laboratory for Molecular Sciences (BNLMS)
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education
- College of Chemistry
- Peking University
- Beijing 100871
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Zhang S, Zhang WX, Xi Z. Semibullvalene and diazasemibullvalene: recent advances in the synthesis, reaction chemistry, and synthetic applications. Acc Chem Res 2015; 48:1823-31. [PMID: 26061608 DOI: 10.1021/acs.accounts.5b00190] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Semibullvalene (SBV) and its aza analogue 2,6-diazasemibullvalene (NSBV) are theoretically interesting and experimentally challenging organic molecules because of four unique features: highly strained ring systems, intramolecular skeletal rearrangement, extremely rapid degenerate (aza-)Cope rearrangement, and the predicted existence of neutral homoaromatic delocalized structures. SBV has received much attention in the past 50 years. In contrast, after NSBV was predicted in 1971 and the first in situ synthesis was realized in 1982, no progress on NSBV chemistry was made until our results in 2012. We have been interested in the reaction chemistry of 1,4-dilithio-1,3-butadienes (dilithio reagents for short), especially for their applications in the synthesis of SBV and NSBV, because (i) the cyclodimerization of dilithio reagents could provide the potential eight-carbon skeleton of SBV from four-carbon butadiene units and (ii) the insertion reaction of dilithio reagents with C≡N bonds of two nitriles could provide a 6C + 2N skeleton that might be a good precursor for the synthesis of NSBV. Therefore, we initiated a journey into the synthesis and reaction chemistry of SBV and NSBV starting from dilithio reagents that has been ongoing since 2006. In this Account, we outline mainly our recent achievements in the synthesis, structural characterization, reaction chemistry, synthetic application, and theoretical/computational analysis of NSBV. Two efficient strategies for the synthesis of NSBV from dilithio reagents and nitriles via oxidant-induced C-N bond formation are described. Structural investigations of NSBV, including X-ray crystal structure analysis, determination of the activation barrier for the aza-Cope rearrangement, and theoretical analysis, show that the localized structure of NSBV is the predominant form and that the homoaromatic delocalized structure exists as a minor component in the equilibrium. We also discuss the reaction chemistry and synthetic applications of NSBV. Several novel reaction patterns have been explored, including thermolysis, C-N bond insertion, rearrangement-cycloaddition, oxidation, and nucleophilic ring-opening reactions. Diverse and interesting N-containing polycyclic skeletons can be constructed, such as nickelaazetidine, 1,5-diazatriquinacenes, and triazabrexadienes, which are not available by other means. Our results show that NSBV not only features a rapid aza-Cope rearrangement with a low activation barrier but also acts as unique synthetic reagent that is significantly different from aziridine. The strained rigid ring systems as a whole can be involved in the reactions. Our achievements highlight two significant advances: (i) the well-established efficient synthesis and isolation of NSBV has greatly accelerated the development of NSBV chemistry, and (ii) the previously unattainable molecules have become "normal" and routine starting materials for the synthesis of otherwise unavailable but interesting structures. We expect that our pursuits will inspire and help direct future chemical and physical research on NSBV.
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Affiliation(s)
- Shaoguang Zhang
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Wen-Xiong Zhang
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Zhenfeng Xi
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
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Zhan M, Zhang S, Huang Z, Xi Z. Synthesis of α,α,α′,α′-Tetrachloro-Δ1-bipyrrolines and 4,8-Dichloro-2,6-diazasemibuvallenes. Org Lett 2015; 17:1026-9. [DOI: 10.1021/acs.orglett.5b00136] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ming Zhan
- Beijing
National Laboratory for Molecular Sciences (BNLMS), Key Laboratory
of Bioorganic Chemistry and Molecular Engineering of Ministry of Education,
College of Chemistry, Peking University, Beijing 100871, China
| | - Shaoguang Zhang
- Beijing
National Laboratory for Molecular Sciences (BNLMS), Key Laboratory
of Bioorganic Chemistry and Molecular Engineering of Ministry of Education,
College of Chemistry, Peking University, Beijing 100871, China
| | - Zhe Huang
- Beijing
National Laboratory for Molecular Sciences (BNLMS), Key Laboratory
of Bioorganic Chemistry and Molecular Engineering of Ministry of Education,
College of Chemistry, Peking University, Beijing 100871, China
| | - Zhenfeng Xi
- Beijing
National Laboratory for Molecular Sciences (BNLMS), Key Laboratory
of Bioorganic Chemistry and Molecular Engineering of Ministry of Education,
College of Chemistry, Peking University, Beijing 100871, China
- State
Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, CAS, Shanghai 200032, China
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Zhang S, Zhan M, Wang Q, Wang C, Zhang WX, Xi Z. Synthesis of semibullvalene derivatives via Co2(CO)8-mediated cyclodimerization of 1,4-dilithio-1,3-butadienes. Org Chem Front 2014. [DOI: 10.1039/c3qo00019b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Zhang S, Wei J, Zhan M, Luo Q, Wang C, Zhang WX, Xi Z. 2,6-Diazasemibullvalenes: Synthesis, Structural Characterization, Reaction Chemistry, and Theoretical Analysis. J Am Chem Soc 2012; 134:11964-7. [DOI: 10.1021/ja305581f] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Shaoguang Zhang
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of the Ministry of Education, College of
Chemistry, Peking University, Beijing 100871,
China
| | - Junnian Wei
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of the Ministry of Education, College of
Chemistry, Peking University, Beijing 100871,
China
| | - Ming Zhan
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of the Ministry of Education, College of
Chemistry, Peking University, Beijing 100871,
China
| | - Qian Luo
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of the Ministry of Education, College of
Chemistry, Peking University, Beijing 100871,
China
| | - Chao Wang
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of the Ministry of Education, College of
Chemistry, Peking University, Beijing 100871,
China
| | - Wen-Xiong Zhang
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of the Ministry of Education, College of
Chemistry, Peking University, Beijing 100871,
China
| | - Zhenfeng Xi
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of the Ministry of Education, College of
Chemistry, Peking University, Beijing 100871,
China
- State Key Laboratory
of Organometallic
Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
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Bao X, Hrovat DA, Borden WT. Calculations of the Effects of Methyl Groups on the Energy Differences between Cyclooctatetraene and Bicyclo[4.2.0]octa-2,4,7-triene and between Their Iron Tricarbonyl Complexes. J Org Chem 2012; 77:956-65. [DOI: 10.1021/jo202157n] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiaoguang Bao
- Department of Chemistry and the Center for Advanced,
Scientific Computing and Modeling, University of North Texas, 1155 Union Circle, #305070, Denton, Texas 76203-5070,
United States
| | - David A. Hrovat
- Department of Chemistry and the Center for Advanced,
Scientific Computing and Modeling, University of North Texas, 1155 Union Circle, #305070, Denton, Texas 76203-5070,
United States
| | - Weston Thatcher Borden
- Department of Chemistry and the Center for Advanced,
Scientific Computing and Modeling, University of North Texas, 1155 Union Circle, #305070, Denton, Texas 76203-5070,
United States
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Seefelder M, Heubes M, Quast H, Edwards WD, Armantrout JR, Williams RV, Cramer CJ, Goren AC, Hrovat DA, Borden WT. Experimental and Theoretical Study of Stabilization of Delocalized Forms of Semibullvalenes and Barbaralanes by Dipolar and Polarizable Solvents. Observation of a Delocalized Structure that Is Lower in Free Energy than the Localized Form. J Org Chem 2005; 70:3437-49. [PMID: 15844976 DOI: 10.1021/jo0502089] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[reaction: see text] UV/vis spectra of thermochromic semibullvalenes 1 and barbaralanes 2, which undergo rapid degenerate Cope rearrangements, display temperature-dependent shoulders (1b, 1d, 1e) or absorption maxima (1c, 2c, 2f) at the low-energy side of their strong UV bands. These long-wavelength absorptions are ascribed to Franck-Condon transitions from delocalized structures 1(deloc) and 2(deloc). Gibbs free energy differences, DeltaG*, between delocalized and localized forms were calculated from the temperature dependence of the long-wavelength absorptions. Dipolar and polarizable solvents strongly affect and even may reverse the relative stabilities of the localized and delocalized forms of 1c, 2c, and 2f. For example, DeltaG*(2c) = 8 kJ mol(-)(1) in cyclohexane, 2 kJ mol(-)(1) in dimethylformamide, and -3 kJ mol(-)(1) in N,N'-dimethylpropylene urea (DMPU), so that (2c(deloc))(DMPU) becomes the global minimum. In contrast to the case for 2c, the intensities of the long-wavelength shoulders of the yellow semibullvalenes 1b, 1d, and 1e are only moderately influenced by solvents, and the rates of Cope rearrangements of the nonthermochromic, colorless barbaralanes 2a and 2b, determined by NMR methods, are almost solvent-invariant. In search of the solute properties that are decisive in determining the influence of solvent upon DeltaG*, electrical dipole and quadrupole moments and molecular polarizabilities have been calculated using the B3LYP/6-31G* method and solvation energies have been computed with the conductorlike polarized continuum model (CPCM). The results of these calculations indicate that the solvent effects are due to the greater polarity and polarizability of the delocalized structures relative to the localized structures.
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Affiliation(s)
- Maximilian Seefelder
- Institut für Organische Chemie der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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