Synthesis & Retrosynthesis in Organic Chemistry

Paper Code: 
CHY 321
Credits: 
4
Contact Hours: 
60.00
Max. Marks: 
100.00
Objective: 

Course Objectives :

The course aims to provide an in-depth knowledge of various photochemical reactions & their basic principles which enables students to learn a variety of photochemical reactions and their mechanisms. They will also understand the various organic transformation through disconnection approach.

Course Outcomes (Cos):

COURSE

Learning outcomes (at course level)

Learning and teaching strategies

Assessment Strategies

Paper Code

Paper Title

CHY 321

Synthesis & Retrosynthesis in Organic Chemistry

The students will be able to-

 

CO88- distinguish between thermal and photochemical energies and their effect on the course of chemical  reactions.

CO89- explain various pericyclic reactions i.e. Electrocyclic reactions, Cycloaddition reactions and Sigmatropic reactions.

CO90- comprehend the orbital interactions and orbital symmetry correlations of various pericyclic reactions.

CO91- use / predict retrosynthesis of organic molecules and develop an approach to devise synthetic methods.

Interactive lectures

 

Discussions

 

Tutorials

 

Problem solving

Written test

 

Quiz

 

Assignment

 

Tutorial

 

Group activity

 

Semester end examination

 
 

12.00
Unit I: 
Basics of Photochemistry and Photochemical Reactions of Carbonyl Compounds

Laws of photochemistry. Fate of excited molecules - Jablonskii diagram, intersystem crossing, energy transfer, photosensitization, quenching, quantum yield, Stern-Volmer equation. Photochemical reactions of ketones – alpha cleavage or Norrish type I cleavage, gamma hydrogen transfer or Norrish type II cleavage; photo reductions; Paterno-Buchi reactions; Photochemistry of α,β-unsaturated ketones, β,γ-unsaturated ketones, cyclohexadienones (cross conjugated and conjugated).

10.00
Unit II: 
Photochemistry of Alkenes and Aromatic Compounds

Photochemistry of alkenes: Intramolecular reactions of the olefinic bond – cis-trans  isomerisation (stilbene), cyclization reactions, rearrangement of 1,4 and 1,5-dienes, di-π methane rearrangement.

Photochemistry of aromatic compounds: Photochemical rearrangement, photostationary state, 1, 3, 5 – trimethyl benzene to 1, 2, 4-trimethyl benzene.

Miscellaneous Photochemical Reactions: Barton reaction, photo Fries rearrangement of ethers and anilides, singlet oxygen reactions (photo oxygenation).

10.00
Unit III: 
Pericyclic Reactions -I

General characteristics, classification, molecular orbital symmetry.

Electrocyclic reactions: theories of explanation (FMO, Woodword-Hoffmann and PMO approach), frontier orbitals, electrocyclisation and reterocyclisation of 1,3 butadiene, cyclobutadiene and, hexatriene derivatives, allylic cations (1,5 diphenylpentadienyl cation) and  allylic anions (1,5 diphenylpentadienyl anion), ring opening in bicycle [4.1.0] heptane derivatives, valence tautomerism.

10.00
Unit IV: 
Pericyclic Reactions–II

Cycloaddtion reactions: 2+2, 4+2 cycloaddition, 1, 3-dipolar cycloaddition and cheletropic reactions; stereoselectivity (endo, exo), stereospecific and regioselective hydrogen reactions, Lewis-acid catalysis in Diels’ Alder reaction.

Sigmatropic rearrangements: Suprafacial and antarafacial shifts of H, sigmatropic shifts involving carbon moieties, 3, 3- and 5, 5-sigmatropic rearrangements; Claisen, Cope and Aza-Cope rearrangements; Isomerization of divinyl cyclopropane; Fluxional tautomerism (bullvalene); Ene reaction.

18.00
Unit V: 
Disconnection Approach in Organic Synthesis

Synthons and synthetic equivalents, Types-d1, d2, d3 and d4 synthons, disconnection approach, functional group inter-conversions, the importance of the order of events in organic synthesis, one group C-X and two group C-X disconnections, chemoselectivity, reversal of polarity, cyclisation reactions, amine synthesis; principle of protection of alcohol, amine, carbonyl and carboxyl groups.

One and Two Group C-C Disconnections:

Alcohols and carbonyl compounds, regioselectivity, alkene synthesis, uses of alkynes and aliphatic nitro compounds in organic synthesis; Diels’ Alder reaction, 1,3-difunctionalised compounds, α,β-unsaturated carbonyl compounds, control in carbonyl condensations, 1,5-difunctionalised compounds, Michael addition and Robinson annelation.

 

References: 
  • CRC Handbook of Organic Photochemistry and Photobiology; Second Edition; W. Horspool and F. Lenci; CRC Press LLC, US, 2004.
  • Fundamentals of Photochemistry; Third Edition; K.K. Rohatagiand Mukherjee; New Age International Publishers Pvt. Ltd., New Delhi, 2007.
  • Molecular Reactions and Photochemistry; First Edition; C. H. Depuy and L. Orville  Chapman; Prentice-Hall of India Pvt. Ltd, New Delhi, 1988.
  • Reaction Mechanism in Organic Chemistry; Third Edition; S.M. Mukherjee and S.P. Singh; Macmillan, India Ltd., New Delhi, 2003.
  • Advanced Organic Chemistry Part A & B; Fifth Edition; F. A. Carey and R. J. Sundberg; Springer, US, 2007.
  • Designing Organic Synthesis: A Programmed Introduction to the SythonApproach; First Edition; S. Warren; John Wiley and Sons, Great Britain, 2010.
  • Organic Synthesis- Concepts, Methods and Starting Materials; J. Fuhrhop and G.Penzillin; Second Edition; Wiley-Vch,New York: 2003.
  • Modern Methods of Organic Synthesis; Fourth Edition; W. Carruthers; Cambridge Univ. Press, UK, 2005.
Academic Year: 
2020-2021
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