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The crystal structure of the title compound, C15H20N2orDippIm, is reported. At 106 (2) K, the molecule has monoclinicP21/c symmetry with four molecules in the unit cell. The imidazole ring is rotated 80.7 (1)° relative to the phenyl ring. Intermolecular stabilization primarily results from close contacts between the N atom at the 3-position on the imidazole ring and the C—H bond at the 4-position on the neighboringDippIm, with aryl–aryl distances outside of the accepted distance of 5 Å for π-stacking.
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Purinyl N -directed aroylation of 6-arylpurine ribo- and 2′-deoxyribonucleosides, and mechanistic insights
The purinyl nitrogen atom is an effective metalation director, which in the presence of Pd(OAc)2,t-BuOOH, and aryl aldehydes, leads to acylation of the aryl ring at the C6 position of the purine.
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- Award ID(s):
- 1953574
- PAR ID:
- 10538650
- Publisher / Repository:
- The Royal Society of Chemistry (UK)
- Date Published:
- Journal Name:
- Organic & Biomolecular Chemistry
- Volume:
- 22
- Issue:
- 33
- ISSN:
- 1477-0520
- Page Range / eLocation ID:
- 6718 to 6726
- Subject(s) / Keyword(s):
- Palladium, nucleoside, aldehyde, aroyl, C-H bond activation, radical
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Palladium‐catalyzed aryl amination and Heck arylation reactions are complementary transformations, generally requiring a suitable catalyst combination and a base. With substrates containing both an amino group and a vinyl moiety, control of C─N versus C─C reactivity can lead to regiodivergent functionalizations. With this focus, reactions of silyl‐protected 8‐vinyl 2'‐deoxyadenosine and adenosine with aryl bromides and iodides have been studied. Pd(OAc)2, Pd2(dba)3, and preformed dichloro[1,1′‐bis(di‐t‐butylphosphino)ferrocene]palladium (II) (Pd‐118) were evaluated as metal sources. Ligands tested were Xantphos, DPEphos, BIPHEP, and DPPF, with Cs2CO3and K3PO4as bases. In toluene as solvent, the Pd(OAc)2/Xantphos/Cs2CO3combination was uniquely capable of predominantN6arylation. Aryl bromides and iodides gave comparable product yields. Replacement of Cs2CO3with K3PO4redirected arylation from the nitrogen atom to the vinyl carbon atom, and all other catalyst, ligand, and base combinations gave Cvinylarylation as well. Simply switching from Pd(OAc)2to Pd2(dba)3resulted in loss of theN6‐selectivity and Cvinylarylation was favored. Based upon these results, using two structurally similar catalytic systems sequential CvinylandN6arylations of the nucleosides were accomplished. Some of the products were converted to other novel nucleoside analogues. Because some compounds were fluorescent, their photophysical properties were assessed experimentally and computationally.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1039/D4OB00689E
