1,6- and 1,7-Regioisomers of Asymmetric and Symmetric Perylene Bisimides

 1,6- and 1,7-Regioisomers of Asymmetric and Symmetric Perylene Bisimides

Molecules 2014, 19(1), 327-341; doi:10.3390/molecules19010327

  http://www.mdpi.com/1420-3049/19/1/327/htm

 


 






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N,N-Dimethyl-5-nitropyridin-2-amine

N,N-Dimethyl-5-nitropyridin-2-amine³⁰ (3d)

Yellow solid; mp 155-157 °C; ¹H NMR (DMSO-d₆, 400 MHz) δ 9.02 (d, 1H, J 2.8 Hz), 8.26 (dd, 1H, J 9.2; 2.8 Hz), 6.80 (d, 1H, J 9.2 Hz), 3.25 (s, 6H); IR (KBr) ν_max/cm^-1: 2924, 2854, 1597, 1335, 1295, 1118, 810; MS (CI method): 168 (M+1, 100%).

30. Heindel, N. D.; Kannewell, P. D.; Chem. Commun. 1969, 38. 

Journal of the Brazilian Chemical Society

Print version ISSN 0103-5053

J. Braz. Chem. Soc. vol.21 no.8 São Paulo  2010

http://dx.doi.org/10.1590/S0103-50532010000800005

see

http://www.scielo.br/scielo.php?pid=S0103-50532010000800005&script=sci_arttext

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2-(3-BROMOPHENYL)-6-(TRIFLUOROMETHYL)PYRAZOLO[1,5-a]PYRIDINE

2-(3-BROMOPHENYL)-6-(TRIFLUOROMETHYL)PYRAZOLO[1,5-a]PYRIDINE

The pyrazolo[1,5-a]pyridine (4) exhibits the following characteristics:

mp 59-60 °C;

IR (film) cm^-1 1647, 1460, 1334, 1321, 1157, 1112, 1076, 1052;

TLC: R_f = 0.38 (silica gel, 4:1 hexanes:ethyl acetate);

¹H NMR pdf (400 MHz, DMSO-d₆)

δ: 7.24 (s, 1 H), 7.35 (d, 1 H, J = 9.2 Hz), 7.39 (t, 1 H, J = 8.0 Hz), 7.54 (d, 1 H, J = 8.0 Hz), 7.81 (d, 1 H, J = 9.2 Hz), 7.95 (d, 1 H, J = 8.0 Hz), 8.12 (m, 1 H), 9.26 (s, 1 H);

¹³C NMR pdf (100 MHz, DMSO-d₆)

δ: 96.3, 115.3 (q), 119.7, 122.7, 122.7, 125.4, 125.6, 128.5 (q), 129.1, 131.4, 132.1, 134.7, 142.1, 153.6;

¹⁹F NMR pdf (376 MHz, DMSO-d₆) δ: -59.73;

LRMS (ESI) m/z (%): 341 (100), 342 (25), 343 (83), 344 (17);

HRMS (FAB) m/z M⁺ calcd for C₁₄H₈BrF₃N₂: 339.9823 found: 339.9827.

Anal. Calc for C₁₄H₈BrF₃N₂: C, 49.29; H, 2.36; N, 8.21. Found: C, 49.26; H, 2.33; N, 8.11.

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NMR Spectroscopic Investigations of Mixed Aggregates Underlying Highly Enantioselective 1,2-Additions of Lithium Cyclopropylacetylide to Quinazolinones

Organolithium reagents can also perform enantioselective nucleophilic addition to carbonyl and its derivatives, often in the presence of chiral ligands. This reactivity is widely applied in the industrial syntheses of pharmaceutical compounds. An example is the Merck and Dupont synthesis of Efavirenz, a potent HIV reverse transcriptase inhibitor. Lithium acetylide is added to a prochiral ketone to yield a chiral alcohol product. The structure of the active reaction intermediate was determined by NMR spectroscopy studies in the solution state and X-ray crystallography of the solid state to be a cubic 2:2 tetramer.

Collum, D.B. et al. (2001). "NMR Spectroscopic Investigations of Mixed Aggregates Underlying Highly Enantioselective 1,2-Additions of Lithium Cyclopropylacetylide to Quinazolinones". J. Am. Chem. Soc. 123: 9135–9143. doi:10.1021/ja0105616.

The solution structures of mixed aggregates derived from lithium alkoxides and lithium acetylides were investigated as part of a program to develop practical syntheses of quinazolinone-based nonnucleoside reverse transcriptase inhibitors. Low-temperature ⁶Li, ¹³C, and ¹⁵N NMR spectroscopies reveal that mixtures of lithium cyclopropylacetylide (RCCLi), a (+)-carene-derived amino alkoxide (R*OLi), and lithium hexamethyldisilazide (LiHMDS) in THF/pentane afford a (RCCLi)₃(R*OLi) mixed tetramer, a C₂-symmetric and asymmetric (RCCLi)₂(R*OLi)₂ mixed tetramer, and a C₃-symmetric (RCCLi)(R*OLi)₃ mixed tetramer. Analogous mixtures of RCCLi/R*OLi in Et₂O and Me₂NEt also provide 3:1, 2:2, and 1:3 mixed tetramers. The stereochemistry of aggregation is highly sensitive to the medium. The C₂-symmetric (RCCLi)₂(R*OLi)₂ mixed tetramer is formed in Et₂O, whereas the asymmetric isomer is formed in Me₂NEt. LiHMDS in THF is shown to be an efficient proton scavenger without forming LiHMDS−RCCLi or LiHMDS−R*OLi mixed aggregates. LiHMDS−RCCLi mixtures form mixed aggregates in Me₂NEt.

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2D NMR contour plot of a dehydroannulene

2D NMR contour plot of a dehydroannulene
 

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The Power of MestReNova Data Processing and Analysis Applied to 60 MHz 1H NMR Real Time Reaction Monitoring

........
 see............http://process-nmr.com/WordPress/?cat=7

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Solution structures by NMR of a novel antifungal drug: Petriellin A

Petriellin A is a novel cyclic depsipeptide antifungal compound consisting of nine L-configured residues, one D-phenyllactic acid (PhLac) and three unknown chiral centres: two N-methyl-threonines (MeThr1 & MeThr2) and one N-methyl-isoleucine (MeIle). NMR experiments including 2D ROESY, NOESY along with structural and energy calculations predicted that the unknown chiral centres were all L-configured, which was later verified chemically. Simulated annealing, dynamics calculations and minimisation processes showed Petriellin A to have a folded “C-shaped” structure.

Org. Biomol. Chem., 2006,4, 3802-3807

DOI: 10.1039/B608434F   http://pubs.rsc.org/en/content/articlelanding/2006/ob/b608434f#!divAbstract