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Barbara Zajc
Title Investigator
Faculty Rank Professor
Degree PhD
Institution City College, CUNY
Department Chemistry
Clusters Cancer
HIV/AIDS
Infectious and Immunological Diseases
Address
The City College of New York
Department of Chemistry
160 Convent Avenue
City New York
State NY
Postal Code 10031
Telephone 212-650-8926
Fax 212-650-6107
Email
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Awards and Honors icon

1991 National Institutes of Health Fogarty Fellowship
2012 The City University of New York Recognition as Outstanding Mentor

Narrative icon

  Background

Prof. Zajc obtained the PhD degree from the University of Ljubljana, Slovenia, and did postdoctoral work as a Fogarty Fellow at the National Institutes of Health, Bethesda. She moved from University of Ljubljana, where she was a tenured faculty member, to The City College of New York, where she is currently Professor of Chemistry with tenure.

Research

Our research is in the area of organofluorine chemistry, with the focus on development of novel regiospecific fluorination methods, and the use of fluorine as a probe in studies related to metabolism and biological activity of environmental pollutants. The importance for this area of research is exemplified in the fact that over 150 commercial pharmaceuticals contain fluorine atom.

In the area of methods development, novel fluorinated building blocks are synthesized and their reactivities are studied. These building blocks are then used for polyfunctionalization, via a modular synthesis approach. Specifically, we are developing a series of fluorinated Julia-Kocienski reagents, where fluorine atom is introduced via metalation-electrophilic fluorination. To gain a deeper understanding of the chemical methodology, reactivities of these reagents are studied in olefination reactions, and also compared with unfluorinated analogs. The overall goal of our work is the development of a “chemical fluoroolefination toolbox” for the synthesis of diverse functionalized fluorinated alkenes. We are also involved with the development of biologically important compounds, such as potential anti-tumor and antiviral agents, via our fluorination chemistry approaches.

In the studies related to the influence of environmental pollutants on human health, we are utilizing fluorine atom to modulate biological activity. In this area, our research involves synthesis of fluorinated analogs of environmental pollutants, their putative metabolites and DNA conjugates, for structure activity studies. This often entails the development of stereoselective methodologies, evaluation of chirality in products, and multistep syntheses.

NIH Awarded Grants icon

  Research projects funded by the National Institutes of Health (NIH), the Centers for Disease Control (CDC), the Food and Drug Administration (FDA), and the Department of Veterans Affairs (VA)

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1.
2010Fluorine as a Probe in Polycyclic Aromatic Hydrocarbon Carcinogenesis Studies5S06GM008168-30
2.
2009Fluorine as a Probe in Polycyclic Aromatic Hydrocarbon Carcinogenesis Studies5S06GM008168-29
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2008Fluorine as a Probe in Polycyclic Aromatic Hydrocarbon Carcinogenesis Studies5S06GM008168-28
4.
2007Fluorine as a Probe in Polycyclic Aromatic Hydrocarbon Carcinogenesis Studies2S06GM008168-27

Publications icon

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1. Lakshman MK, Tine FA, Khandaker TA, Basava V, Agyemang NB, Benavidez MSA, Gaši M, Guerrera L, Zajc B. KHF2, a mild and selective desilylating agent for phenol t-butyldimethylsilyl (TBDMS) ethers. Synlett. 2017 Mar; 28(3):381-385.
2. Banerjee S, Sinha S, Pradhan P, Caruso A, Liebowitz D, Parrish D, Rossi M, Zajc B. Regiospecifically Fluorinated Polycyclic Aromatic Hydrocarbons via Julia-Kocienski Olefination and Oxidative Photocyclization. Effect of Fluorine Atom Substitution on Molecular Shape. J Org Chem. 2016 05 20; 81(10):3983-93.
3. Kumar R, Singh G, Todaro LJ, Yang L, Zajc B. E- or Z-Selective synthesis of 4-fluorovinyl-1,2,3-triazoles with fluorinated second-generation Julia-Kocienski reagents. Org Biomol Chem. 2015 Feb 07; 13(5):1536-49.
4. Chowdhury M, Mandal SK, Banerjee S, Zajc B. Synthesis of regiospecifically fluorinated conjugated dienamides. Molecules. 2014 Apr 10; 19(4):4418-32.
5. Ayeni DO, Mandal SK, Zajc B. Julia-Kocienski Approach to Trifluoromethyl-Substituted Alkenes1. Tetrahedron Lett. 2013 Nov 06; 54(45):6008-6011.
6. Singh G, Kumar R, Swett J, Zajc B. Modular synthesis of N-vinyl benzotriazoles. Org Lett. 2013 Aug 16; 15(16):4086-9.
7. Kumar R, Zajc B. Stereoselective synthesis of conjugated fluoro enynes. J Org Chem. 2012 Oct 05; 77(19):8417-27.
8. Mandal SK, Ghosh AK, Kumar R, Zajc B. Expedient synthesis of a-substituted fluoroethenes. Org Biomol Chem. 2012 Apr 28; 10(16):3164-7.
9. Kumar R, Pradhan P, Zajc B. Facile synthesis of 4-vinyl- and 4-fluorovinyl-1,2,3-triazoles via bifunctional "click-olefination" reagents. Chem Commun (Camb). 2011 Apr 07; 47(13):3891-3.
10. Zajc B, Kumar R. Synthesis of Fluoroolefins via Julia-Kocienski Olefination. Synthesis (Stuttg). 2010; 2010(11):1822-1836.
11. Ghosh AK, Zajc B. Fluorinated 1-phenyl-1H-tetrazol-5-yl sulfone derivatives as general reagents for fluoroalkylidene synthesis. J Org Chem. 2009 Nov 20; 74(22):8531-40.
12. Ghosh AK, Banerjee S, Sinha S, Kang SB, Zajc B. Alpha-fluorovinyl Weinreb amides and alpha-fluoroenones from a common fluorinated building block. J Org Chem. 2009 May 15; 74(10):3689-97.
13. del Solar M, Ghosh AK, Zajc B. Fluoro-Julia olefination as a mild, high-yielding route to alpha-fluoro acrylonitriles. J Org Chem. 2008 Nov 07; 73(21):8206-11.
14. He M, Ghosh AK, Zajc B. Julia Olefination as a General Route to Phenyl (alpha-Fluoro)vinyl Sulfones. Synlett. 2008 Apr 01; 2008(7):999-1004.
15. Ghosh AK, Lagisetty P, Zajc B. Direct synthesis of 8-fluoro purine nucleosides via metalation-fluorination. J Org Chem. 2007 Oct 26; 72(22):8222-6.
16. Bae S, Mah H, Chaturvedi S, Jeknic TM, Baird WM, Katz AK, Carrell HL, Glusker JP, Okazaki T, Laali KK, Zajc B, Lakshman MK. Synthetic, crystallographic, computational, and biological studies of 1,4-difluorobenzo[c]phenanthrene and its metabolites. J Org Chem. 2007 Sep 28; 72(20):7625-33.
17. Lakshman MK, Keeler JC, Ngassa FN, Hilmer JH, Pradhan P, Zajc B, Thomasson KA. Highly diastereoselective synthesis of nucleoside adducts from the carcinogenic benzo[a]pyrene diol epoxide and a computational analysis. J Am Chem Soc. 2007 Jan 10; 129(1):68-76.
18. Zajc B, Kake S. Exceptionally mild, high-yield synthesis of alpha-fluoro acrylates. Org Lett. 2006 Sep 28; 8(20):4457-60.
19. Ghosh AK, Zajc B. High-yield synthesis of fluorinated benzothiazolyl sulfones: general synthons for fluoro-julia olefinations. Org Lett. 2006 Apr 13; 8(8):1553-6.
20. Okazaki T, Laali KK, Zajc B, Lakshman MK, Kumar S, Baird WM, Dashwood WM. Stable ion study of benzo[a]pyrene (BaP) derivatives: 7,8-dihydro-BaP, 9,10-dihydro-BaP and its 6-halo derivatives, 1- and 3-methoxy-9,10-dihydro-BaP-7(8H)-one, as well as the proximate carcinogen BaP 7,8-dihydrodiol and its dibenzoate, combined with a comparative DNA binding study of regioisomeric (1-, 4-, 2-) pyrenylcarbinols. Org Biomol Chem. 2003 May 07; 1(9):1509-16.
21. Zajc B, Grahek R, Kocijan A, Lakshman MK, Kosmrlj J, Lah J. Evaluation of the enantiomeric resolution of 7,8-dihydroxy-7,8-dihydrobenzo[a]-pyrene and its 6-fluoro and 6-bromo derivatives on polysaccharide-derived stationary phases. J Org Chem. 2003 Apr 18; 68(8):3291-4.
22. Kramata P, Zajc B, Sayer JM, Jerina DM, Wei CS. A single site-specific trans-opened 7,8,9,10-tetrahydrobenzo[a]pyrene 7,8-diol 9,10-epoxide N2-deoxyguanosine adduct induces mutations at multiple sites in DNA. J Biol Chem. 2003 Apr 25; 278(17):14940-8.
23. Simhadri S, Kramata P, Zajc B, Sayer JM, Jerina DM, Hinkle DC, Wei CS. Benzo[a]pyrene diol epoxide-deoxyguanosine adducts are accurately bypassed by yeast DNA polymerase zeta in vitro. Mutat Res. 2002 Oct 31; 508(1-2):137-45.
24. Zajc B. Synthesis of (+/-)-trans-7,8-Dihydrodiol of 6-Fluoro-benzo[a]pyrene via Hydroxyl-Directed Regioselective Functionalization of Substituted Pyrene. J Org Chem. 1999 Mar 19; 64(6):1902-1907.
25. Custer L, Zajc B, Sayer JM, Cullinane C, Phillips DR, Cheh AM, Jerina DM, Bohr VA, Mazur SJ. Stereospecific differences in repair by human cell extracts of synthesized oligonucleotides containing trans-opened 7,8,9, 10-tetrahydrobenzo[a]pyrene 7,8-diol 9,10-epoxide N2-dG adduct stereoisomers located within the human K-ras codon 12 sequence. Biochemistry. 1999 Jan 12; 38(2):569-81.
26. Lipinski LJ, Ross HL, Zajc B, Sayer JM, Jerina DM, Dipple A. Effect of single benzo[a]pyrene diol epoxide-deoxyguanosine adducts on the action of DNA polymerases in vitro. Int J Oncol. 1998 Aug; 13(2):269-73.
27. Page JE, Zajc B, Oh-hara T, Lakshman MK, Sayer JM, Jerina DM, Dipple A. Sequence context profoundly influences the mutagenic potency of trans-opened benzo[a]pyrene 7,8-diol 9,10-epoxide-purine nucleoside adducts in site-specific mutation studies. Biochemistry. 1998 Jun 23; 37(25):9127-37.
28. LeBreton PR, Huang CR, Fernando H, Zajc B, Lakshman MK, Sayer JM, Jerina DM. Multiple fluorescence lifetimes for oligonucleotides containing single, site-specific modifications at guanine and adenine corresponding to trans addition of exocyclic amino groups to (+)-(7R,8S,9S,10R)- and (+)-(7S,8R,9R,10S) -7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene. Chem Res Toxicol. 1995 Apr-May; 8(3):338-48.

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Keywords
Fluorine
Hydrocarbons, Fluorinated
Triazoles
Halogenation
Alkenes
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