Computational Study of
Substitution Effects in
Acetylenic Diels-Alder
Reactions
Emily Sotelo
Mentor Dr. Adam Moser
Overview
Background
Research Motivation
Methods: Quantum Chemistry
Calculations
Results
Implications for future work
Background
Research Motivation
Method
Calculations
Results
Future Work
The Diels-Alder
Reaction
 Discovered by chemists Otto Diels and Kurt Alder
in 1928-recognized with a Nobel Prize in
Chemistry in 1950
1. Ring Formation
Background
Research Motivation
Method
Calculations
Results
Future Work
Importance of
the Diels-Alder
Reaction
2. High Stereochemical Control
Background
Research Motivation
Method
Calculations
Results
Future Work
Reaction
Components
Energetically
favorable due to
formation of new σ
bonds
Diene only reacts in
s-cis conformation
Electron
withdrawing
groups activate the
dienophile
Concerted
mechanism
Kinetic control can
dominate
Background
Research Motivation
Method
Calculations
Results
Future Work
Reaction of
Interest
Background
Research Motivation
Method
Calculations
Results
Future Work
Reaction of
Interest
Background
Research Motivation
Method
Calculations
Results
Future Work
Literature
Review
 The Diels-Alder Reaction of Acetylene is slower
than that of Ethylene
 Higher activation energy due to distortion
energy
 Only performed in lab using catalysts & radicals
 Adding activating groups to both ends of the
triple bond increases the reactivity
 Seems to be this gap in the literature discussing the
very basic components of this very important
Background
Research Motivation reaction of acetylene and butadiene
Method
Calculations
Results
Future Work
My Research
 We have decided to study this computationally
because you can examine lot reaction properties
quickly
Background
Research Motivation
Method
Calculations
Results
Future Work
Quantum
Chemistry
Branch of computational chemistry which uses
mathematical approximations to solve the Schrödinger
equation
Method
 Describes what
approximation will be
used to solve the
equation
Basis Set
 Describes what
math is available to
solve this equation
Background
Research Motivation
Method
Calculations
Results
Future Work
Substituents
Background
Research Motivation
Method
Calculations
Results
Future Work
Calculations
 ΔH, ΔG, Δ‡H, and Δ‡G
 HOMO-LUMO Energies
Background
Research Motivation
Method
Calculations
Results
Future Work
Single
Substitution
EWG
Background
Research Motivation
Method
Calculations
Results
Future Work
HOMO-LUMO
Background
Research Motivation
Method
Calculations
Results
Future Work
Single
Substitution
EDG
Background
Research Motivation
Method
Calculations
Results
Future Work
Double
Substitution
Background
Research Motivation
Method
Calculations
Results
Future Work
Dihedral Scan
Background
Research Motivation
Method
Calculations
Results
Future Work
Dihedral Scan
Background
Research Motivation
Method
Calculations
Results
Future Work
Dihedral Scan
Background
Research Motivation
Method
Calculations
Results
Future Work
Dihedral Scan
Background
Research Motivation
Method
Calculations
Results
Future Work
Dihedral Scan
Background
Research Motivation
Method
Calculations
Results
Future Work
Dihedral Scan
Background
Research Motivation
Method
Calculations
Results
Future Work
Dihedral Scan
Background
Research Motivation
Method
Calculations
Results
Future Work
Summary
 Most effective substituent to lower
activation barrier
 Lowers LUMO energy
 This barrier is lowered further by
substituting both ends of the triple
bond
 Steric effects seem to be the
dominating force when locking the
conformation of the dienophile
Background
Research Motivation
Method
Calculations
Results
Future Work
 Continue to work with more substituents to
see if these trends continue
 Substitute both reactants to gain a better
understanding of not only
thermodynamics/kinetics but stereochemistry
 Continue to work with the dihedral scanning
 Use higher, more accurate levels of theory to
 See if trends continue
 Closer to experimental data
Next Steps
Acknowledgments
Dr. Adam Moser
Dr. Sean Mulcahy
Science Hall faculty
Loras College
Peers, Friends and
Family
 Cramer, C.J. (2002). Essentials of Computational Chemistry.
Hoboken, NJ: Wiley.
 Dai, M, Sarlah, D, Yu, M. Danishefsky, S, Jones, G, Houk, KN. 2006.
Highly Selective Dielss-Alder Reactions of Directly Connected Enyne
Dieneophiles. J Am Chem Soc 129, 645-657.
References
 Froese, RDJ, Coxon, JM, West, SC, Morokuma, K. 1997. Theoreical
Studies of DA reaction of Acetylenic Compounds. J. Org. Chem 63,
6991-6996.
 Nicolaou KC, Snyder SA, Montagnon T, Vassilikogiannakis G
(2002). The Diels-Alder Reaction in total synthesis. Angew Chem
Int Ed 41: 1668-1698.
 Rahm, A., Rheingold, A.L, Wulff, WD. 2000. Asymmetric Diels-Alder
Reactions with Chiral Acetylenic Carbene Complexes as Dienophiles.
Tetrahedrom 56, 4951-4965
 Smith, J. (2011). Organic Chemistry 3rd Edition. New York, NY:
McGraw-Hill.
EXTRA SLIDES
Thermodynamic
vs. Kinetic
Control
Δ‡G
Reaction Profile
&
T-State
Calculations
Method:
Hartree Fock
Basis Set:
6-31G(d)
 Equations which describe the
shape of the orbital
 Slater and Gaussian
Quantum
Chemistry
 Treats each electron
separately
 Assumes frozen nucleus
 The basis set is a split valance
meaning there are two types
of electrons, core and valence
electrons with the valence
electrons participating in the
reaction behavior of
molecule.
 Split valence basis sets uses
this knowledge to treat these
two types of electrons
differently.
HOMO-LUMO
Changing
Levels of
Theory