76304-54-6Relevant academic research and scientific papers
Metal-Free Directed C?H Borylation of Pyrroles
Wang, Zheng-Jun,Chen, Xiangyang,Wu, Lei,Wong, Jonathan J.,Liang, Yong,Zhao, Yue,Houk, Kendall N.,Shi, Zhuangzhi
supporting information, p. 8500 - 8504 (2021/03/16)
Robust strategies to enable the rapid construction of complex organoboronates in selective, practical, low-cost, and environmentally friendly modes remain conspicuously underdeveloped. Here, we develop a general strategy for the site-selective C?H borylation of pyrroles by using only BBr3 directed by pivaloyl groups, avoiding the use of any metal. The site-selectivity is generally dominated by chelation and electronic effects, thus forming diverse C2-borylated pyrroles against the steric effect. The formed products can readily engage in downstream transformations, enabling a step-economic process to access drugs such as Lipitor. DFT calculations (wB97X-D) demonstrate the preferred positional selectivity of this reaction.
Expanded scope of synthetic bacteriochlorins via improved acid catalysis conditions and diverse dihydrodipyrrin-acetals
Krayer, Michael,Ptaszek, Marcin,Kim, Han-Je,Meneely, Kelly R.,Fan, Dazhong,Secor, Kristen,Lindsey, Jonathan S.
experimental part, p. 1016 - 1039 (2010/04/04)
(Chemical Equation Presented) Bacteriochlorins are attractive candidates for a wide variety of photochemical studies owing to their strong absorption in the near-infrared spectral region. The prior acid-catalysis conditions [BF 3 · O(Et)2 in CH3CN at room temperature] for self-condensation of a dihydrodipyrrin-acetal (bearing a geminal dimethyl group in the pyrroline ring) typically afforded a mixture of three macrocycles: the expected 5-methoxybacteriochlorin (MeOBC-type), a 5-unsubstituted bacteriochlorin (HBC-type), and a free base B,D-tetradehydrocorrin (TDC-type). Here, a broad survey of >20 acids identified four promising acid catalysis conditions of which TMSOTf/2,6-di-tert-butylpyridine in CH2Cl 2 at room temperature was most attractive owing to formation of the 5-methoxybacteriochlorin as the sole macrocycle regardless of the pyrrolic substituents in the dihydrodipyrrin-acetal (electron-withdrawing, electron-donating, or no substituent). Eleven new dihydrodipyrrin-acetals were prepared following standard routes. Application of the new acid catalysis conditions has afforded diverse bacteriochlorins (e.g., bearing alkyl/ester, aryl/ester, diester, and no substituents) in a few days from commercially available starting materials. Consideration of the synthetic steps and yields for formation of the dihydrodipyrrin-acetal and bacteriochlorin underpins evaluation of synthetic plans for early installation of bacteriochlorin substituents via the dihydrodipyrrin-acetal versus late installation via derivatization of β-bromobacteriochlorins. Treatment of the 5-methoxybacteriochlorins with NBS gave regioselective 15-bromination when no pyrrolic substituents were present or when each pyrrole contained two substituents; on the other hand, the presence of a β-ethoxycarbonyl group caused loss of regioselectivity. The 15 new bacteriochlorins prepared herein exhibit a long-wavelength absorption band in the range 707-759 nm, providing tunable access to the near-infrared region. Taken together, this study expands the scope of available bacteriochlorins for fundamental studies and diverse applications. 2010 American Chemical Society.
De novo synthesis of bacteriochlorins
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Page/Page column 25; 28, (2008/06/13)
A method of making a bacteriochlorin is carried out by condensing a pair of compounds of Formula II to produce the bacteriochlorin, wherein R is an acetal or aldehyde group. The condensing may be carried out in an organic solvent, preferably in the presence of an acid. The bacteriochlorins are useful for a variety of purposes such as active agents in photodynamic therapy, luminescent compounds in flow cytometry, solar cells, light harvesting arrays, and molecular memory devices.
De novo synthesis of stable tetrahydroporphyrinic macrocycles: Bacteriochlorins and a tetradehydrocorrin
Kim, Han-Je,Lindsey, Jonathan S.
, p. 5475 - 5486 (2008/04/18)
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 α, 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 B12. 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) β-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 (λQy = 737 nm, εQy = 130 000 M-1 cm-1) and emission (λem = 744 nm, Φf = 0.14). In summary, this simple entry to stable bacteriochlorins and tetradehydrocorrins should facilitate a wide variety of applications.
Synthesis of 3-Arylpyrroles and 3-Pyrrolylacetylenes by Palladium-Catalyzed Coupling Reactions
Alvarez, Alejandro,Guzman, Angel,Ruiz, Alicia,Velarde, Esperanza,Muchowski, Joseph M.
, p. 1653 - 1656 (2007/10/02)
Efficacious methods for the synthesis of 3-arylpyrroles or 3-pyrrolylacetylenes are described based on the palladium-catalyzed coupling of appropriate 1-(triisopropylsilyl)-3-substituted pyrroles with aryl halides or monosubstituted acetylenes and subsequ
Rhodium-Catalysed Reactions of Propargylamines with CO/H2. Formation of Pyrroles and Butenolides
Campi, Eva M.,Fallon, Gary D.,Jackson, W. Roy,Nilsson, Ylva
, p. 1167 - 1178 (2007/10/02)
Rhodium-catalysed reactions of (arylpropargyl)amines with CO/H2 give β-arylpyrroles in good yields.Reactions of (alkylpropargyl)amines gave alkylpyrroles together with butenolides which are formed in an unusual reaction that probably involves double carbonylation, reduction of one carbonyl function and removal of the amine function by hydrogenolysis.The single-crystal X-ray structure of 5-methyl-N,3-diphenylpyrrole-2-carboxamide is recorded.
A HYDROFORMYLATION ROUTE TO Β-SUBSTITUTED PYRROLES
Campi, Eva M.,Jackson, W. Roy,Nilsson, Ylva
, p. 1093 - 1094 (2007/10/02)
Rhodium catalysed hydroformylation of readily available β-alkynylamines gives 3-substituted or 2,4-disubstituted pyrroles in good yields.
