Chemistry CHEM S-20ab Lecture Notes - Lecture 14: Conjugated System, Benzyl Group, Bayerischer Rundfunk
Chemistry E-2a: Lecture 10 December 18, 2008
14
Sample Synthesis Problem (from old exam)
• You should be able to find at least three completely different synthetic routes for the
following problem!
Show all reagents and intermediates for the multi-step synthesis below. You may use any organic or
inorganic reagents in your synthesis, but you must begin with the indicated starting material. You do not need
to show any mechanisms. The correct answer will require fewer than 5 steps.
HC CH
H
O
Starting Material:
Desired Product
Chemistry S-20ab
Week 3
18
More than One Alkene In a Molecule
• Molecules with 2 C=C bonds are dienes. Draw the structures of the following dienes:
1,4-cyclohexadiene
1,3-cyclohexadiene
1,3-butadiene
1,2-butadiene
• Molecules with 3 C=C bonds are trienes. Draw the structure of 1,3,5-cyclooctatriene.
Reading: Chapter 15 (introduction)
Document Summary
You should be able to find at least three completely different synthetic routes for the following problem! Show all reagents and intermediates for the multi-step synthesis below. You may use any organic or inorganic reagents in your synthesis, but you must begin with the indicated starting material. You do not need to show any mechanisms. The correct answer will require fewer than 5 steps. When two c=c bonds share a single carbon atom, they are called cumulated double bonds. The simplest compound that contains cumulated double bonds is allene, c3h4. Draw the structure of allene and determine the geometry and hybridization of each atom. This molecule can not be prepared as a stable compound. When two double bonds are on adjacent carbons they are said to be conjugated. Conformational analysis of rotation around the single bond in 1,3-butadiene shows that it has two stable conformations, both of which are (nearly) planar.