Question

Question. The alkaloid coniine has been isolated from hemlock and purified. Its molecular formula is. Treatment of coniine with excess methyl iodide, followed by silver oxide and heating, gives the pure (S)-enantiomer of N,N-dimethyloct-7-ene-4-amine. Propose a complete structure for coniine, and show how this reaction gives the observed product.

Short answer

Alkaloid coniine is an antagonist of nicotinic acetylcholine receptor and is highly volatile and not recommended for consumption in mammals. Its extraction occurs from Hemlock plant and it has oily liquid appearance. In organic solvents, it is generally soluble and is optically active in nature.

Step-by-step solution

Step-1. The alkaloid coniine:

Alkaloid coniine is an antagonist of nicotinic acetylcholine receptor and is highly volatile and not recommended for consumption in mammals. Its extraction occurs from Hemlock plant and it has oily liquid appearance. In organic solvents, it is generally soluble and is optically active in nature.

Step-2. Reaction of coniine with excess methyl iodide followed by silver oxide and heating:

Coniine undergoes reaction with excess methyl iodide and forms quarternary ammonium salt which is unstable and further treatment silver oxide and heat, less substituted alkene or Hoffmann alkene is formed. Silver oxide acts as a base and abstracts the hydrogen which leads to the formation of less substituted alkene. There is no change in stereochemistry of the chiral center present in reactant as no reaction occurs at that chiral center.

Reaction of coniine with excess methyl iodide followed by silver oxide and heating