User:Benjah-bmm27/degree/2/APD

Introduction

"Stereochemistry and Conformation", Professor Anthony Davis

Stereochemistry

• Stereochemistry

Chirality

• Optical rotation
  • Levorotation and dextrorotation
  • Specific rotation
  • Polarimetry and polarimeters
• Cahn–Ingold–Prelog priority rules
• Chirality (chemistry)
  • Axial chirality
    • Atropisomers: "stereoisomers resulting from hindered rotation about single bonds where the steric strain barrier to rotation is high enough to allow for the isolation of the conformers". Example: substituted biphenyls.
      Angew. Chem. Int. Ed. (2005) 44, 5384–5427,
      Tetrahedron Lett. (1990) 31, 5409–5412
  • Planar chirality — synonymous with axial chirality?
• Stereocenter
• Absolute configuration
• Enantiomer
  • Racemic mixture
• Diastereomer
• Meso compound

Conformation

• Molecular configuration
• Conformational isomerism
• Alkane stereochemistry
• Decalins

Cyclooalkanes

• Baeyer strain
• Pitzer strain
• Cycloalkanes
• Cyclopropanes - planar by definition
• Cyclobutanes - puckered to avoid eclipsing interactions
• Cyclopentanes - envelope conformation
• Cyclohexane conformation - chair form, boat form, twist boat, twist chair
• Cyclooctanes have many low-energy conformations, but the stablest one is the boat-chair (Jmol)
• Anomeric effect: anomers are epimers of cyclic saccharides that differ only in their configuration at the anomeric carbon (= the hemiacetal or hemiketal carbon)

Stereoelectronic effects and reactions

• Steric effects
• Stereoelectronic effects
• Bürgi-Dunitz angle
• Stereoselectivity vs. stereospecificity
• re and si faces
• Chiral auxiliary
• Chiral derivatizing agents:
  • Mosher's acid
  • Pirkle's alcohol
  • a chiral amino alcohol (use with diethylzinc on enantiotopic carbonyls)