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Alkynes Reaction Acidity Synthesis.  Complex of Acetylene  Bonds.

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Presentation on theme: "Alkynes Reaction Acidity Synthesis.  Complex of Acetylene  Bonds."— Presentation transcript:

1 Alkynes Reaction Acidity Synthesis

2  Complex of Acetylene  Bonds

3 Hydrocarbon Comparison

4 Alkyne Nomenclature

5 Enes with Ynes

6 Endiyne Antitumor Agents

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11 Catalytic Hydrogenation

12 Lindlar’s Catalyst

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

14 Dissolved Lithium in NH 3 trans Alkenes

15 Addition of HX

16 Br 2 Addition

17 Oxymercuration Hydration Markovnikov

18 Enol – Keto Tautomerization Intermolecular

19 Oxymercuration Mechanism

20 Hydroboration Hydration Anti-Markovnikov

21 Hydroboration Mechanism

22 Draw the Products

23

24 Ozonolysis

25 Acidity of Terminal Alkynes

26 Acetylide Formation

27 Alkylation of Acetylide Ions Homologations using S N 2 rxn

28 Multi-step Syntheses

29 Retrosynthetic Analysis Begin with the Product

30 Fill in the Reagents

31 How Many Steps?

32 5 Steps

33 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.

34 Schematic of the Problem

35 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.

36 Propose Structures for A, B, and C

37 Nucleophilic addition to Carbonyl Compounds

38 Synthesis Problem

39 Retrosynthetic Analysis from acetylene


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