Professor and Chair
Ph.D. Columbia University (1980)
Office: Remsen 109B
Phone: (718) 997-4144
FAX: (718) 997-5531
Current and former
Research Interests: Organic/Organometallic; uses of novel
chemistry in organometallic catalysis, antisense oligonucleotide
and enantioselective catalysis.
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triaryl or trialkyl phosphorus ligands in organometallic compounds are
relatively electron-rich. We have begun investigating novel
N-sulfonyl moieties, the first two of which
we have named
TosL and diTosL(5,
We have shown these ligands to be comparable to fluorinated phosphines
in electron-withdrawing ability. Compound 1 is a chiral
and is easy to prepare in enantiomerically pure form from the amino
12). We are
the many opportunities for steric and electronic tuning of analogues of
The figure below is a movie of the X-ray structure of 1
rotating about the center of the heterocycle ring, and it allows the
to be visualized.
hydroformylation generally gives better results when relatively
phosphines are used. While monodentate TosL gives
regioselectivity and reactivity compared to PPh3 for the
of 1-hexene, use of chelating diTosL is clearly superior
(10). We are presently examining the scope of
reaction in the presence of a variety of N-sulfonyl
Phosphorothioates are useful antisense oligonucleotides with enhanced
to nucleases. Current syntheses give mixtures of configuration at
We are examining chemistry related to that used for 1 above to
chiral phosphorothioates; some initial preliminary results are shown.
years ago we discovered the tungsten nitrosyl Lewis acid
2, in which
the so-called "noncoordinating" anion SbF6¯
is bound via a fluorine atom to tungsten (4). We
X-ray crystal structures of related analogues and 31P and 19F
NMR spectra detailing the anion coordination at low temperature, and at
higher temperatures anion "spinning" via dissociation to tight ion
and finally dissociation to free ions (3, 4).
Compound 2 is an efficient Diels-Alder catalyst, activating
such as acrolein and methyl vinyl ketone by Lewis acid coordination of
tungsten to the carbonyl oxygen as seen in the X-ray structure of 3
(1, 2). Compound 4a
is a chiral catalyst that we have prepared (2),
with a molecule of acrolein coordinated to the metal. Attack by a diene
on the front face of acrolein (away from the phenyl ring as shown for 5
below) will give a chiral product. While 4a is racemic,
reaction gives a 55:45 mixture of coordinated diastereomeric
adducts of acrolein and isoprene, suggesting that a pure enantiomer of
4a would give a 10% e.e. Using the bulkier
group was expected to improve the selectivity, and the diphenyl/di-t-butyl
analog 4b is an excellent catalyst. The enantiomerically
incorporates a chiral-at-phosphorus chelating ligand
with phenyl and t-butyl groups, and catalyzes the reaction of
and isoprene to give the Diels-Alder adduct with 36% e.e. However,
conformational or electronic differences from 4b result in
low yields using 5, so this means of introducing
Group resources: Major equipment includes a
double station glove box equipped with a -35 °C freezer and a mini
antechamber for fast pumping, vacuum lines, Mattson FTIR, Macintosh
and a departmental Bruker 400 MHz NMR equipped with a
QNP probe, VT device, and 60-sample sample-changer.
on undergraduate research - in the Queens College
science journal Nucleus
(14) Hersh, W. H.; Fong, R. H. "Crossover Studies of
Methyl Migration from
Oxygen to Iron in the Iron-Manganese Methoxycarbyne Complex
Cp(CO)Fe(m-COCH3)(m-CO)Mn(CO)MeCp, Organometallics 2005, 24, 4179-4189.
(13) Hersh, W. H.; Klein, L.; Todaro, L. J. "Stereoselective Synthesis
of P-Chiral Phosphorus Compounds from N-tert-Butoxycarbonyl Amino
Acids," J. Org. Chem. 2004, 69, 7355-7358.
(12) Hersh, W.
Xu, P.; Simpson, C. K.; Grob, J.; Bickford, B.; Hamdani, M. S.; Wood,
Rheingold, A. L. "Synthesis and Structural Characterization of
Amino Acid Derived Chiral Phosphorus Compounds," J. Org. Chem. 2004,
(11) Magee, M. P.; Li,
O.; Hersh, W. H. "Synthesis of Electron-Withdrawing Butane- and
Phosphines and Use in Rhodium-Catalyzed Hydroformylation," Dalton
Transactions, 2003, 387-394.
(10) Magee, M. P.; Luo, W.; Hersh,
H. "Electron-Withdrawing Phosphine Compounds in Hydroformylation
1. Syntheses and Reactions Using Mono and Bis(p-toluenesulfonylamino)
(9) Kane, S.; Hersh, W. H. "Periplanar
Coplanar?," J. Chem. Educ. 2000, 77, 1366.
(8) Hersh, W.
Xu, P.; Simpson, C. K.; ,Wood, T.; Rheingold, A. L. "A Chiral
Synthesis and X-Ray Crystal Structure of a
a Trivalent Electron-Withdrawing Amino Acid-Derived Phosphorus
and Synthesis of Its W(CO)5
Adduct," Inorg. Chem. 1998, 37, 384-385.
(7) Hersh, W.
"False AA'X Spin-Spin Coupling Systems in
NMR: Examples Involving Phosphorus and a 20-Year-Old Mystery in
Decoupling," J. Chem. Educ. 1997,
(6) Luo, W.; Fong, R. H.; Hersh,
H. "Synthesis and Oxygen to Iron Methyl Migration Reaction of the
Heterodinuclear Methoxycarbyne Complex Cp(CO)Fe(m-COCH3)(m-CO)Cr(CO)(h6-C6H6),"
1997, 16, 4192-4199.
(5) Hersh, W.
Xu, P.;Wang, B.; Yom, J. W.; Simpson, C. K. "Synthesis of Tungsten
and Nitrosyl Complexes of Monodentate and Chelating Aryl-N-sulfonylphosphoramides,
the First Members of a New Class of Electron-Withdrawing Phosphine
Comparative IR and
and 31P NMR
of Related Phosphorus Complexes," Inorg. Chem.1996, 35,
V.; Hersh, W. H. "Coordination of "Noncoordinating" Anions: Synthesis,
Characterization, and X-ray Crystal Structures of Fluorine-Bridged [SbF6]¯,
Adducts of [R3P(CO)3(NO)W]+.
An Unconventional Order of Anion Donor Strength," Inorg. Chem.
(3) Honeychuck, R. V.; Hersh, W.
"Observation of Anion Spinning in the Dynamic 31P NMR
of Fluorine-Bridged SbF6¯,
Adducts of R3P(CO)3(NO)W+.
Implications for Barriers to Ionization and the Formation of Ion Pairs
and Free Ions in Methylene Chloride and Hexane Solution," J. Am.
Soc. 1989, 111, 6056-6070.
V.; Puckett, C. L.; Honeychuck, R. V.; Hersh, W. H. "Catalysis of
Reactions by Low Oxidation State Transition Metal Lewis Acids: Fact and
Fiction," J. Am. Chem. Soc. 1989,
R. V.; Bonnesen, P. V.; Farahi, J.; Hersh, W. H. "Catalysis of Diene
and Diels-Alder Reactions by an Octahedral Tungsten Nitrosyl Lewis
X-ray Crystal Structure of the
Org. Chem. 1987, 52, 5293-5296.
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Joshua Mukhlall (Ph.D.)
Eric Chan (Ph.D.)
Sara Burgdorf (undergrad)
Menachem Moskowitz (undergrad)
Last modified April 29, 2007