Functitonal group interconversions

This is the conversion of one functional group into another. Retrosynthetic

  1. Unavailability of starting material

  2. Adjustment of functionality of a known reaction

    • Unwanted product product from excess reaction

  3. To maslk reactive functionality in a molecule

    • Protection groups are used so that you get your reagent to react with the group that you want it to react with that

    • =pph3 means Wittig salt

    • Bases are used to make carbanions as well

  4. To introduce asymmetry into molecules

Vocabulary

Disconnection: curved line to symbolize where the bond is being formed

FGI: arrow symbol

Retron: smallest part of the reaction, core moiety that is being formed

Synthon: imaginary intermediate fragment, can formed from heterolytic(one negative charge, one positive charge)

Reagent: real compound being used to carry out reaction

Synthetic equivalent: in between synthon and retron

Retrosynthesis: process of deconstructing

Chemoselectivty: “chemo” means reaction, reactivity on one specific functional group

Regioselectivity: “regio” means reagent, reactivity on. Markovnikovs: negative charge of reagent attacks carbon with lease number of hydrogens

Stereoselectivity: cis and trans produces different products or noo products

Enantioselectivity

SN1 reaction is done in 2 steps and sn2 is in 1 step

Sulfonates, alcohols, and alkyl halides are the 3 main sources to carry out FGI through nucleophilic attacks.

Tertiary sulfonates are not stable, why?

Sulfonate → Alkyl Halides

  • you need to know the reagents that convert sulfonates into alkyl halides. Should reactions that are not acid specific

Thionyl chloride = socl2

PPh3 is a lewis base

HBr is considered to be harsh conditions

Cl2 is a gas which hard to handle. so carbon tetrachloride or hexachloroacetone can be used instead

pyridine or triethylamine. When acids are used, bases are

hcl gas is mixed with water to put it in liquid form.

Carbon Nucleophiles are basically C(-)

  • CN-R is nitride not cyano group in organic chemistry

  • Replacement of Halide

  • Its very easy to replace cyanide with sulfonate

  • 18-C-6

  • polar aprotic are more polare solvents like dmso NOT water. aprotic means Hydrogens are released aprotic does not

  • PTC means phase transfer catalyst. eXAMPLE OF THIS IS TBAD Cl- and hexadecylbutyphosphonium, and crown ethers, and cryptanes. For crown ethers, they trap the reaction in the crown. Used when using organic solvents and salts because salt doesnt disolve in polar solvents. PTC’s and aprotic solvents are used at the same yime

  • The alkylation of an amine is hard to control

  • Understand that he may give you 2 of the same starting material just to show that there are 2 different outcomes.

  • To convert alcohols to azides they first have to convert to sulfonates then azides

  • LDA is a strong base

  • Azide converting agents: DPPA, DBU, NAN3, LIN3

  • Mitsonobu reaction: always involves alcohols and the reagent that is DIAD DEAD and a nucleophic agent

  • Sulfonamides are also acidic and are anions

Oxygen nucleophiles

  • Best oxygen nucleophiles are alkoxide ions and carboxylate ions, bothe with negative charges

  • Williamson Synthesis -

  • Carboxylates, peopleuse K, Cs, or Na

  • Configuration inversion:

  • Sulfonate esters can also be prepared using mitsonobu conditions

Phosphorus Nucleophiles

  • Uses Phosphines mainly

  • Phosphorus ylide is when there is a dipolar molecule with a formal negative charge atom. It is used to prepare olephines

  • Phosphites -

  • Phosphonates - using HWER reaction. produces a double bond and an activating leaving group attached as well

Sulfur Nucleophiles

  • Easy concept to understand

  • Weinreb Amide

  • Nitriles