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Ibuprofen R form non-active side effects S form active anti-inflammatory

R.B. Woodward (1917-1979) 1st modern synthetic organic chemist Probably greatest organic chemist 1965 Nobel Prize in Chemistry “outstanding achievements in the art of organic synthesis Also made VERY important observations in the development of the Woodward-Hoffman rules of ring closure 1st step in the application of quantum mechanics to organic molecules 1981 Nobel Prize in Chemistry (Roald Hoffmann)

R.B. Woodward (Early Career)

R.B. Woodward (Later Career)

R.B. Woodward

K.C. Nicolaou Penn (1977-1989) Scripps Research Institute and UC-San Diego (1989-present) Modern day R.B. Woodward

K.C. Nicolaou Taxol Isolated in 1967 from bark of Pacific yew tree Lung, ovarian, breast, head and neck cancer 11 stereocenters => 211 = 2048 stereoisomers 2 rings & 1 bicyclic ring

K.C. Nicolaou Brevotoxin B Neurotoxin that binds to voltage-gated sodium channels in nerve cells Naturally found in Karenia brevis which are marine organisms typically found in fish 23 stereocenters => 223 = 8,400,000 stereoisomers 11 trans-fused rings 83 steps, 12 years 91% yield for each step but 0.043% total yield

K.C. Nicolaou Maitotoxin Neurotoxin that binds to calcium channels Naturally produced by Gambierdiscus toxicus which are marine organisms typically found in fish 94 stereocenters => 294 = 1.98 x 1028 stereoisomers 31 trans-fused rings

Atomic Orbitals n l ml Orbital Name 1 1s 2 2s -1 2p +1 3 3s 3p -2 3d n 1s 2 2s -1 2p +1 3 3s 3p -2 3d n l Orbital Name 1 1s 2 2s 2p 3 3s 3p 3d

Linus Pauling (1901-1994) Probably greatest chemist of the 20th century Only person too win 2 unshared Nobel Prizes and only person to win 2 unrelated Nobel Prizes 1954 – Chemistry 1962 - Peace “The Nature of the Chemical Bond” Protein Structure Antibody Structure and Process Molecular cause of Sickle-cell anemia Electronegativity Resonance Vitamin C and the Common Cold

The Periodic Table and Electronegativity

Common Bonding Situations Hydrogen 1 bond Carbon 4 bonds (neutral and 8 electrons) The most common bonding situations that we will encounter for organic compounds are summarized here. Remember, satisfying the octet rule is most important in determining stability; minimizing formal charges is next. Hydrogen prefers one bond. Carbon prefers two bonds. We will also encounter some less stable carbon species. These are not compounds that can be put in a bottle, but they will appear as reactive intermediates in some chemical reactions. Reactive Carbon Species

3 bonds and one unshared pair of electrons Nitrogen 3 bonds and one unshared pair of electrons Other relatively stable species Nitrogen prefers three bonds.

2 bonds and 2 unshared electron pairs Oxygen 2 bonds and 2 unshared electron pairs Other relatively stable species Oxygen prefers two bonds. hydronium ion

1 bond and 3 unshared electron pairs Halogens 1 bond and 3 unshared electron pairs also 4 unshared pairs and negative charge The halogens prefer one bond.

Table 2-6a, p. 51

Table 2-6b, p. 51

These are sigma (s) MOs: symmetrical about the internuclear axis Here are the two overlapping 1s AOs of the two hydrogen atoms. In the simplest model, we picture these as either adding or subtracting. If they add, the waves reinforce between the nuclei, resulting in a lower energy, bonding MO. If they subtract, the waves cancel in the region between the nuclei to give a higher energy, antibonding MO. The place where the AOs cancel is called a node. More nodes means higher energy. σ MOs are symmetrical about the internuclear axis. Rotation about that axis causes no change in amount of overlap. These are sigma (s) MOs: symmetrical about the internuclear axis