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Course
Module: Organic Reaction Mechanisms |
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Introduction to mechanism in organic and biological chemistry;
reactive
intermediates (1 L) |
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Carbocations, structure and mechanism, generation and rearrangements.
NMR
of carbocations in superacids. Stability of carbocations - resonance,
aromaticity, substituent and steric effects. Rearrangements,
neighbouring
group participation; cyclopropyl, aryl, acetoxy groups. Principles
and
concepts in mechanistic studies :- primary kinetic isotope effects,
linear
free energy relationships, resonance and inductive effects, steric
effects,
secondary kinetic isotope effects, hyperconjugation, stereoelectronic
effects, aromatic character, ring strain, non-bonded interactions,
transannular effects, thermodynamic stability. (4L) |
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Carbenes and nitrenes, generation, reactions and rearrangements.
Thermal
rearrangements of carbenes. Singlet and triplet species. (2L) |
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Free radicals; generation and reactions. Free radical chain reactions.
Organotin and Barton methods of generating radicals for organic
synthetic
reactions. Free radical cyclizations and fragmentations. Domino
cyclizations and fragmentations. Radical clocks - cyclopentyl
and
cyclopropylcarbinyl systems. Enediynes to diradicals, natural
enediynes,
synthetic analogues as potential drugs (4L) |
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Selected enzymatic reactions. Cytochrome P450 systems. Aromatase
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aromatization of ring A of steroids. Cyclooxygenase - arachidonic
acid to
prostanoids and leukotrienes. b-Lactam biosynthesis - mechanistic
studies
with isopenicillin N-synthase. Radicals in biology (4L) |
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