De novo synthesis of stable tetrahydroporphyrinic macrocycles: Bacteriochlorins and a tetradehydrocorrin
De novo synthesis of stable tetrahydroporphyrinic macrocycles: Bacteriochlorins and a tetradehydrocorrin
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DOI：
10.1021/jo050467y
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发表时间：
2005-07-08
影响因子：
3.6
通讯作者：
Lindsey, JS
中科院分区：
文献类型：
--
作者：
Kim, HJ;Lindsey, JS
细菌叶绿素（四氢卟啉）是有吸引力的各种光化学应用，由于其在近红外光谱区的强吸收，如细菌光合色素细菌叶绿素a的例子，但往往是不稳定的脱氢，以得到二氢卟酚。四氢可啉（缩环四氢卟啉）在类似于维生素B-12的催化研究中具有吸引力。这种四氢卟啉大环化合物的八步合成从对甲苯甲醛开始，并进行到带有偕二甲基和对甲苯基取代基的二氢二吡咯缩醛（1）。1在含BF_3（.）OEt 2在室温下得到两种游离碱菌绿素和游离碱B，D-四脱氢咕啉的容易分离的混合物。每个菌绿素含有两个偕二甲基以锁定菌绿素氢化水平，在相对的（2，12）P-位置上的对甲苯基取代基，以及在5-（内消旋）位置上不存在（H-BC）或存在（MeO-BC）甲氧基。B，D-四脱氢可啉（TDC）位于可啉和可咯的氢化水平之间的等距离处，是对映体，并且含有两个偕二甲基基团、2，12-二-对甲苯基取代基和在吡咯啉-吡咯连接处的缩醛基团。检查1（2.5-50 mM）和BF 3（.）OEt 2（10-500 mM）显示了H-BC、MeO-BC和TDC中每一种的不同响应面，使得能够相对选择性地制备给定的大环。每种的最高分离收率分别为49%、30%和66%。大环化合物在光照和空气中常规处理时稳定。细菌绿素显示出特有的光谱特征;例如，H-BC显示出近红外吸收（λ（Qy）= 737 nm，λ（Qy）= 130 000 M-1 cm（-1））和发射（Arm = 744 nm，Φ（f）= 0.14）。总之，这种简单的稳定菌绿素和tetradehydrocorrins的入口应促进各种各样的应用。
Bacteriochlorins (tetrahydroporphyrins) are attractive for diverse photochemical applications owing to their strong absorption in the near-infrared spectral region, as exemplified by the bacterial photosynthetic pigment bacteriochlorophyll a, yet often are labile toward dehydrogenation to give the chlorin. Tetradehydrocorrins (ring-contracted tetrahydroporphyrins) are attractive for studies of catalysis analogous to that of vitamin B-12. An eight-step synthesis toward such tetrahydroporphyrinic macrocycles begins with p-tolualdehyde and proceeds to a dihydrodipyrrin-acetal (1) bearing a geminal dimethyl group and a p-tolyl substituent. Self-condensation of 1 in CH3CN containing BF3 (.) OEt2 at room temperature afforded a readily separable mixture of two free base bacteriochlorins and a free base B,D-tetradehydrocorrin. Each bacteriochlorin contains two geminal dimethyl groups to lock-in the bacteriochlorin hydrogenation level, p-tolyl substituents at opposing (2,12) P-positions, and the absence (H-BC) or presence (MeO-BC) of a methoxy group at the 5- (meso) position. The B,D-tetradehydrocorrin (TDC) lies equidistant between the hydrogenation levels of corrin and corrole, is enantiomeric, and contains two geminal dimethyl groups, 2,12-di-p-tolyl substituents, and an acetal group at the pyrroline-pyrrole junction. Examination of the effect of the concentrations of 1 (2.5-50 mM) and BF3 (.) OEt2 (10-500 mM) revealed a different response surface for each of H-BC, MeO-BC, and TDC, enabling relatively selective preparation of a given macrocycle. The highest isolated yield of each was 49, 30, and 66%, respectively. The macrocycles are stable to routine handling in light and air. The bacteriochlorins display characteristic spectral features; for example, H-BC exhibits near-IR absorption (lambda(Qy) = 737 nm, epsilon(Qy) = 130 000 M-1 cm(-1)) and emission (Arm = 744 nm, (Phi(f) = 0.14). In summary, this simple entry to stable bacteriochlorins and tetradehydrocorrins should facilitate a wide variety of applications.