Hyland Michael A, Hewage Nisansala, Panther Kimberly, Nimthong-Roldán Arunpatcha, Zeller Matthias, Samaraweera Milinda, Gascon José A, Brückner Christian
Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3060, United States.
Department of Chemistry, Youngstown State University , One University Plaza, Youngstown, Ohio 44555-3663, United States.
J Org Chem. 2016 May 6;81(9):3603-18. doi: 10.1021/acs.joc.6b00273. Epub 2016 Apr 26.
Syntheses and optical properties of mono- and bis-chromene-annulated bacteriochlorins are described. Known monochromene-annulated meso-(pentafluorophenyl)chlorin is susceptible to a regioselective OsO4-mediated dihydroxylation, generating two monochromene-annulated trihydroxybacteriochlorin stereoisomers: either the newly introduced vic-cis-diol functionality is on the same side as the vic-cis-diol moiety the chromene-annulation was based on or on the opposite side. Treatment of the two isomers with heat or base generates different sets of bis-chromene-annulated bacteriochlorin stereo- and regioisomers. Detailed 1D and 2D (1)H and (19)F NMR spectroscopic investigations allowed the characterization of the isomers that formed. The regioselectivity of the second annulation reaction was rationalized computationally on steric grounds. The bacteriochlorin-type optical spectra of the mono- and bis-chromene-annulated bacteriochlorins are modulated as a result of the annulation, with each isomer possessing a unique spectrum, attributed to the effects the regiochemically distinct annulations have on the conformation of the chromophore. The formation of a bis-chromene-annulated chlorin from the bacteriochlorins is also described, including its X-ray crystal structure, revealing some details of the metrics of the chromene-annulated moiety. The vic-diol functionality of monochromene-annulated trihydroxybacteriochlorins is also susceptible to oxidation and ring-expansion reactions, generating chromene-annulated pyrrole-modified chlorins incorporating oxazolone and morpholine moieties. The work expands the body of work on the synthesis and optical fine-tuning of meso-aryl-substituted bacteriochlorins.
本文描述了单苯并色烯和双苯并色烯稠合细菌叶绿素的合成及其光学性质。已知的单苯并色烯稠合的中位（五氟苯基）二氢卟吩易受区域选择性OsO₄介导的二羟基化作用，生成两种单苯并色烯稠合的三羟基细菌叶绿素立体异构体：新引入的邻位顺式二醇官能团与苯并色烯稠合所基于的邻位顺式二醇部分在同一侧或在相反侧。用热或碱处理这两种异构体可生成不同组的双苯并色烯稠合细菌叶绿素立体异构体和区域异构体。详细的一维和二维¹H和¹⁹F NMR光谱研究使得能够对形成的异构体进行表征。基于空间原因通过计算对第二次稠合反应的区域选择性进行了合理化解释。单苯并色烯和双苯并色烯稠合细菌叶绿素的细菌叶绿素型光谱由于稠合作用而受到调制，每种异构体都具有独特的光谱，这归因于区域化学上不同的稠合对发色团构象的影响。还描述了由细菌叶绿素形成双苯并色烯稠合二氢卟吩，包括其X射线晶体结构，揭示了苯并色烯稠合部分的一些结构细节。单苯并色烯稠合的三羟基细菌叶绿素的邻位二醇官能团也易受氧化和扩环反应的影响，生成含有恶唑酮和吗啉部分的苯并色烯稠合吡咯修饰的二氢卟吩。这项工作扩展了关于中位芳基取代细菌叶绿素的合成和光学微调的研究范围。
