Sterically Hindered Porphyrins

Abstract

The neutron-proton capture reaction has been measured at E, = 25.6 MeV. From the data the total and the differential cross section at 0" were determined. The results are compared with photodisintegration data and theoretical calculations and found to be in agreement with both.

Pyrroles as terminators in cationic cyclizations. The preparation of 5,6,7,8-tetrahydroindolizidines and 6,7,8,9-tetrahydro-5H-pyrrolo[1,2-a]azepines

“…According to the general procedure for the tosylation of pyrrole diols, 0.29 g (1.74 mmol) of 34 (R4 = R5 = H) and 0.393 g (2.06 mmol) of p-toluenesulfonyl chloride were combined in pyridine (7 mL) to provide crude 34 (R4 = p-Ts, R5 = H) as a viscous yellow oil. Flash chromatography on a column of silica gel yielded 0.462 g, 83%, of 34 (R4 = p-Ts, R6 = H) as a yellow viscous liquid: XH NMR (250 MHz, C6D6) 7.75 (d, J = 8 Hz, 2), 6.72 (d, J = 8 Hz, 2), 6.43 (t, J = 2 Hz, 2), 6.30 (t, J = 2 Hz, 2), 4.02 (br s, 1), 3.81 (m, 2), 3.54 (m, 1), 3.31 (t, J = 7 Hz, 2), 1.84 (s, 3), 1.60 (m, 1), 1.40 (m, 1), 1.02 (m, 2); IR (neat) 3100, 3050, 2930, 2885,1500,1280,1090,1070, 730 cm"1; EI-MS (70 eV), m/z (relative intensity) 152 ( + 1, 20.4), 151 (M+, 64.9), 134 (38.4), 120 (44.1), 106 (12.6), 93 (19.0), 81 (48.9), 80 (base), 68 (32.5), 53 (14.3).…”

“…The meso-tetraphenylporphyrins offer attractive features in this context and have been used in a wide variety of model studies. 1,2 Tetraphenylporphyrin was first synthesized 50 years ago by Rothemund, who caused benzaldehyde and pyrrole in pyridine to react in a sealed bomb at 150 °C for 24 h. 3 The yields were low and the conditions so severe that few substituted benzaldehydes could be converted to the corresponding porphyrin. The Rothemund conditions were obviously based on the premise that the porphyrin is aromatic, aromatic compounds are stable, and therefore merely cracking the initially formed adducts of benzaldehyde and pyrrole at high temperatures should give the porphyrin.…”

Structural Dynamics and Relaxation Processes with Participation of Excited Singlet and Triplet States in Sterically Hindered Porphyrins and Their Chemical Dimers

“…[14,[19][20][21][26][27][28][29] Analysis of numerous X-ray structural data, [30][31][32][33] results of spectral-kinetic investigations, [34][35][36][37][38][39][40][41] and quantum-chemical calculations [42][43][44][45][46][47][48][49][50][51][52][53][54] indicate that simultaneous introduction of bulky peripheral substituents in β-and meso-positions of molecules of tetrapyrrole compounds leads to spatial distortions of the macrocycle, considerably changing its geometry and electronic structure as well as the dynamics of relaxation processes. To date, there are a lot of additional publications being devoted to the study of sterically hindered tetrapyrrole macrocycles by methods of electronic, [55][56][57][58][59][60][61][62][63][64][65] vibrational, [66][67]…”

Phenyl Substituted Porphyrins. Part 5. Acylation of Aminophenylporphyrins

“…The common acylation agents include various carboxylic acid derivatives: chloroanhydrides, [2][3][4][5][6][7][8][9][10][11][12][13] anhydrides, [14][15][16][17][18][19] and carboxylic acids themselves as well. [20][21][22][23][24][25][26] In the latter case the common solvents are methylene chloride, [24,26] THF [22,23,25] and chloroform.…”