Following is the structural formula of the principal sex pheromone of the Douglas fir tussock moth (Orgyia pseudotsugata), a severe defoliant of the fir trees of western North America. (Z)-6-Heneicosene-11-one Several syntheses of this compound have been reported, one of which is shown: HO Br Br (Z)-6-Heneicosene-11-one alkyl bromide 1 hemiacetal 1 alkyl bromide 2 This synthesis involves the following steps: 1. Alkyl bromide 2 reacts with triphenylphosphine and butyllithium to form ylide 1; 2. Hemiacetal 1 is in equilibrium with aldehyde 2; 3. Aldehyde 2 reacts with ylide 1 to form oxaphosphetane 3; 4. Oxaphosphetane 3 expels triphenylphosphine oxide to form alkene 4 (the alkene is primarily formed in the desired Z configuration); 5. Alkene 4 is oxidized with PCC to form aldehyde 5; 6. Alkyl bromide 1 reacts with magnesium and ether to form Grignard reagent 6; 7. Grignard reagent 6 adds to aldehyde 5 to form tetrahedral intermediate 7; 8. Tetrahedral intermediate 7 reacts with dilute aqueous acid to form alcohol 8; 9. Alcohol 8 is oxidized with chromic acid to yield (Z)-6-Heneicosene-11-one. Diagram these steps on a separate sheet of paper, and then draw the structure of tetrahedral intermediate 7.

Following is the structural formula of the principal sex pheromone of the Douglas fir tussock moth (Orgyia pseudotsugata), a severe defoliant of the fir trees of western North America. (Z)-6-Heneicosene-11-one Several syntheses of this compound have been reported, one of which is shown: HO Br Br (Z)-6-Heneicosene-11-one alkyl bromide 1 hemiacetal 1 alkyl bromide 2 This synthesis involves the following steps: 1. Alkyl bromide 2 reacts with triphenylphosphine and butyllithium to form ylide 1; 2. Hemiacetal 1 is in equilibrium with aldehyde 2; 3. Aldehyde 2 reacts with ylide 1 to form oxaphosphetane 3; 4. Oxaphosphetane 3 expels triphenylphosphine oxide to form alkene 4 (the alkene is primarily formed in the desired Z configuration); 5. Alkene 4 is oxidized with PCC to form aldehyde 5; 6. Alkyl bromide 1 reacts with magnesium and ether to form Grignard reagent 6; 7. Grignard reagent 6 adds to aldehyde 5 to form tetrahedral intermediate 7; 8. Tetrahedral intermediate 7 reacts with dilute aqueous acid to form alcohol 8; 9. Alcohol 8 is oxidized with chromic acid to yield (Z)-6-Heneicosene-11-one. Diagram these steps on a separate sheet of paper, and then draw the structure of tetrahedral intermediate 7.

Organic Chemistry

8th Edition

ISBN:9781305580350

Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Chapter18: Functional Derivatives Of Carboxylic Acids

Section: Chapter Questions

Problem 18.38P: A step in a synthesis of PGE1 (prostaglandin E1, alprostadil) is the reaction of a trisubstituted...

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