Following are the final steps in one industrial synthesis of vitamin A acetate. H,SO, ÓH (1) (2) (3) Pseudoionone B-Ionone (racemic) OH Br Ph P, HBr (4) (5) (racemic) OCCH3 Vitamin A acetate (a) Propose a mechanism for the acid-catalyzed cyclization in Step 1. (b) Propose reagents to bring about Step 2. (c) Propose a mechanism for formation of the phosphonium salt in Step 4. (d) Propose reagents to bring about Step 3. (e) Show how Step 5 can be completed by a Wittig reaction.

Following are the final steps in one industrial synthesis of vitamin A acetate. H,SO, ÓH (1) (2) (3) Pseudoionone B-Ionone (racemic) OH Br Ph P, HBr (4) (5) (racemic) OCCH3 Vitamin A acetate (a) Propose a mechanism for the acid-catalyzed cyclization in Step 1. (b) Propose reagents to bring about Step 2. (c) Propose a mechanism for formation of the phosphonium salt in Step 4. (d) Propose reagents to bring about Step 3. (e) Show how Step 5 can be completed by a Wittig reaction.

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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Question

Following are the final steps in one industrial synthesis of vitamin A acetate.
H,SO,
ÓH
(1)
(2)
(3)
Pseudoionone
B-Ionone
(racemic)
OH
Br
Ph P, HBr
(4)
(5)
(racemic)
OCCH3
Vitamin A acetate
(a) Propose a mechanism for the acid-catalyzed cyclization in Step 1.
(b) Propose reagents to bring about Step 2.
(c) Propose a mechanism for formation of the phosphonium salt in Step 4.
(d) Propose reagents to bring about Step 3.
(e) Show how Step 5 can be completed by a Wittig reaction.

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