MXN Bonds Broken -Bonds Formed

PCC/Jones

• Bonds Broken: Sigma (O-H), Sigma (C-H)

• Bonds Formed: Pi (C-O)

Periodic Oxidation

• Bonds Broken: Sigma (O-H) x2, Sigma (C-C)

• Bonds Formed: Pi (C-O) x2

Pinnick Oxidation

• Bonds Broken: Sigma (C-O), Sigma (O-H), Sigma (C-H)

• Bonds Formed: Pi (C-O), Sigma (C-H), Sigma (O-H)

Ether Decomposition

• Bonds Broken: Sigma (C-O), Sigma (O-H), Sigma (C-H)

• Bonds Formed: Pi (C-O), Sigma (C-H)

mCPBA & Epoxide Creation

• Bonds Broken: Sigma (O-O), Sigma (O-H), Pi (C-C)

• Bonds Formed: Sigma (C1-O), Sigma (C2-O), Sigma (O-H)

Br2

• Net Change 

  • Broken: (C-C) pi, sigma (Br-Br)

  • Formed: (Br-C) sigma x2

E2 w/ non-bulky base

• Net Change 

  • Broken: sigma (C-LG), sigma (C-H)

  • Formed: pi (C-C)

E2 w/ Bulky Base

• Net Change 

  • Broken: Sigma (C-H), Sigma (C-LG)

  • Formed: pi (C-C)

E1

• Net Change

  • Broken: Sigma (O-H), Sigma (C-H)

  • Formed: Pi (C-C)

Hydride/Methyl Shift Trend

Hydride or methyl shift (Broken: H-C#, Formed: H-C(#+1))

PBr3

• Net Changes 

  • Broken: Sigma (P-Br), Sigma (C-O)

  • Formed: Sigma (C-Br), Sigma (O-P)

OMs or OTs Addition

• Net Change 

  • Broken: Sigma (O-H), Sigma (S-Cl)

  • Formed: Sigma (O-S)

Cuprate Reaction w/ Cu-LG Electrophile

• Net Change 

  • Bonds Broken: Sigma (Br-C), Sigma (R-Cu)

  • Bonds Formed: Sigma (Br-Cu), Sigma (C-R)

Silyl Ether Formation

• Net Change 

  • Bonds Broken: Sigma (O-H)

  • Bonds Formed: Sigma (Si-O), Sigma (N-H)

Silyl Ether Destruction

• Net Change 

  • Bonds Broken: Sigma (O-H), Sigma (O-Si)

  • Bonds Formed: Sigma (Si-F), Sigma (O-H)

LiAlH₄ & aq w/up Rxn w/ Ketones/Aldehydes

• Net Change

  • Bonds Broken: Pi (C-O)

  • Bonds Formed: Sigma (C-H)

Wittig Formation

• Net Change 

  • Bonds Broken: Sigma (C-LG), Sigma (C-H)

  • Bonds Formed: Sigma/Pi (C-Ph), Sigma (C-H)

Wittig Reaction

• Net Effect 

  • Bonds Broken: 

    • Sigma (C-O), Sigma (C-P)

  • Bonds Formed:

    • Pi (O-P), Sigma (O-P) Sigma (C-C) bond Pi (C-C) bond

Acid or Base Catalysis of Ketone/Aldehyde—> Gem-Diol

• Bonds Broken: Pi (C-O)

• Bonds Formed: Sigma (O-H), Sigma (HO-C)

Reversion of Gem-Diol Back to Ketone/Aldehyd

• Bonds Broken: Sigma (C-OH), Sigma (O-H)

• Bonds Formed: Pi (C-O)

Acid & Base Catalysis of Ketone/Aldehyde—>Hemi-Acetal

Bonds Broken: Pi (C-O), Sigma (O-H)

Bonds Formed: Sigma (C-OR)

Acid Catalysis of K/A—> Acetal

• Net Effect 

  • Bonds Broken: Pi (C-O)

  • Bonds Formed: Sigma (C-OR), Sigma (C-OR)

Dihydropyran Protection

Bonds Broken: Pi (C-C)

Bonds Formed: Sigma (C-H), Sigma (RO-C)

Dihydropyran Deprotection

Bonds Broken: Sigma (RO-C)

Bonds Formed: Sigma (HO-C)