Alkynes Reaction Acidity Synthesis

 Complex of Acetylene  Bonds

Hydrocarbon Comparison

Alkyne Nomenclature

Enes with Ynes

Endiyne Antitumor Agents

Catalytic Hydrogenation

Lindlar’s Catalyst

H 2 on a Poisoned Catalyst Prevents Over-Reduction cis Alkenes

Dissolved Lithium in NH 3 trans Alkenes

Addition of HX

Br 2 Addition

Oxymercuration Hydration Markovnikov

Enol – Keto Tautomerization Intermolecular

Oxymercuration Mechanism

Hydroboration Hydration Anti-Markovnikov

Hydroboration Mechanism

Draw the Products

Ozonolysis

Acidity of Terminal Alkynes

Acetylide Formation

Alkylation of Acetylide Ions Homologations using S N 2 rxn

Multi-step Syntheses

Retrosynthetic Analysis Begin with the Product

Fill in the Reagents

How Many Steps?

5 Steps

An unknown compound (A) has a formula of C 11 H 1 4. Treatment of A with H 2 /Pd-carbon gives B (C 11 H 20 ). Treatment of A with H 2 on a Lindlar catalyst gives C (C 11 H 16 ). Ozonolysis of C followed by workup with Zn, HOAc affords formaldehyde and the tricarbonyl compound shown below.

Schematic of the Problem

An initial approach to this problem is to determine the number of degrees of unsaturation in each of the molecules A, B, and C. When A (C 11 H 14, 5 o unsat.) is hydrogrenated, B (C 11 H 20, 2 o unsat.) is formed. That means that 3  bonds reacted (3 mol. equivalents) to form B. When A is treated with H 2 over a Lindlar (poisoned) catalyst, 1 mol equiv. of H 2 reacts. Since this reaction is specific for the reduction of alkynes to alkenes, 2 of the 3  bonds in A are in the form of a triple bond. The remaining  bond must be an alkene. We have accounted for three of the five degrees of unsaturation in A, therefore the other two must be rings since they do not react with H 2.

Propose Structures for A, B, and C

Nucleophilic addition to Carbonyl Compounds

Synthesis Problem

Retrosynthetic Analysis from acetylene