Lecture 01, 2

• What does stereochemistry concern itself with?

  The three-dimensional arrangement of atoms
• Why is molecular flexibility important in stereochemistry?

  It affects the spatial arrangement of atoms
• What are stereoisomers?

  Compounds with the same connectivity but different arrangements
• How do drugs interact with biological systems?

  By interacting with targets like receptors or enzymes
• What are the types of isomers mentioned?

  • Constitutional Isomers: Different connectivity
  • Stereoisomers: Same connectivity
  • Conformational Isomerism: Same connectivity, molecular flexibility
  • Optical Isomerism: Chirality
  • Geometrical Isomerism: Enantiomers and Diastereoisomers
• What is the Lock and Key mechanism in drug action?

  It describes how drugs mimic or block substrates
• What happens when thalidomide is converted from (R)–Thalidomide?

  It converts to (S)-Thalidomide
• What does confirmation refer to in stereochemistry?

  Changes in structure due to rotation about sigma bonds
• What does configuration refer to in stereochemistry?

  Three-dimensional arrangement requiring bond breaking
• What is conformation in stereochemistry?

  Relative positioning of atoms over time
• How does conformation change over time?

  It changes due to free rotation around bonds
• What factors govern the shape of small molecules?

  Bond lengths, angles, and rotations
• What determines the bond length of a single covalent bond?

  Atomic RadiusA + Atomic RadiusB
• How do bond angles minimise steric clash?

  By forming optimal angles between groups
• What is the ideal bond angle for sp3 hybridised carbon?

  109.5 degrees
• Why can't bond rotation occur along double or triple bonds?

  Restrictions imposed by π bonds
• What are conformations in open chain compounds?

  Different arrangements formed by sigma bond rotation
• What do Newman Projections assess?

  The effect of bond rotations
• What is the difference between staggered and eclipsed conformations?

  Staggered is more stable than eclipsed
• What is the dihedral angle in conformations?

  The angle between substituents
• Why are cycloalkanes with 5-7 atoms most stable?

  They minimise angle and torsional strain

  
• What is the bond angle in cyclopropane?

  60 degrees
• How does cyclohexane eliminate angle strain?

  By adopting a chair conformation

  
• What is the overall strain of cyclohexane?

  Zero
• What happens to substituents during cyclohexane ring flipping?

  Axial becomes equatorial and vice versa

  
• Why is the boat conformation less stable than the chair conformation?

  It has torsional strain and steric clashes
• What is the significance of staggered conformation in cyclohexane?

  It minimises steric clashes between protons
• What are the types of stereoisomers discussed?

  • Geometric Isomers
  • Diastereomers
  • Enantiomers
• How does the C=C double bond affect geometric isomers?

  It prevents rotation, fixing substituent positions
• What does the Cahn-Ingold-Prelog convention help determine?

  The E or Z configuration of isomers
• What does E stand for in E/Z nomenclature?

  Entgegan, meaning across
• What does Z stand for in E/Z nomenclature?

  Zusammen, meaning together
• How are priority rules determined for atoms in the Sequence Rules?

  By their atomic number
• How are isotopes prioritised in the Sequence Rules?

  By their mass
• What happens when two identical atoms are bonded?

  Priority is determined by the next atoms
• How are multiple bonded groups treated in unsaturated systems?

  As single bonds for priority determination
• What is an example of a disubstituted cyclohexane?

  1,3 dimethylcyclohexane
• What distinguishes the cis isomer of 1,3 dimethylcyclohexane?

  Both methyl groups are axial or equatorial

  
• What distinguishes the trans isomer of 1,3 dimethylcyclohexane?

  One methyl group is axial and one equatorial