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Chem112BPractice5 - N H CO 2 Me O MeO 2 C H N MeO 2 C Me O...

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Chem 112B Spring 2007 Practice Problems (05/05/07) Problem 1 Determine the oxidation state of the metal in each transition metal complex shown and tabulate the total electron count for each complex. In addition, state which of the five elementary mechanistic steps (i.e., oxidative addition, β -elimination etc…) is illustrated by each equation. Fe CH 3 CO OC CO CO Li CO Fe CO OC CO CO O CH 3 Li Elementary Step Electron Count Rh Cl PPh 3 Ph 3 P Ph 3 P O H Electron Count Rh PPh 3 Ph 3 P Ph 3 P H Cl O C 6 H 5 Problem 2 Based on our discussions on diazonium salts, propose a plausible mechanism for the following reaction. What is A and what gas would you predict is produced? O OH NH 2 HNO 2 A Gas O O Problem 3 The Mannich reaction is a powerful reaction for the formation of alkaloids. Propose a mechanism that accounts for the formation of porantherine, A , from B . The last sequence involves a reduction and elimination. Notice that B is symmetrical! N Porantherine (A) NH 2 O B O O
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Problem 4 Provide an arrow pushing mechanism to account for the following transformation.
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Unformatted text preview: N H CO 2 Me O MeO 2 C H N MeO 2 C Me O H 1. NaBH 4 2. Ms 2 O 3. LiBr Ms 2 O = S O S O O O O Me Me N H CO 2 Me O MeO 2 C H N MeO 2 C Me Br Problem 5 Many tumors in breast cancer are estrogen-dependent. Drugs that interfere with estrogen binding have antitumor activity and may even help prevent tumor occurrence. A widely used antiestrogen drug is tamoxifen. Given that tamoxifen is synthesized from A using an enamine intermediate synthesized from A and a Grignard reagent, propose a synthesis of tamoxifen. O O N O N tamoxifen A Problem 6 The Wolff-Kishner reaction and the Wharton fragmentation use hydrazine (H 2 NNH 2 ) to make a hydrazone and involve the loss of N 2 . Propose a mechanism for the following Wharton fragmentation reaction. O O OH 1. H 2 NNH 2 , Heat 2. Acidic Workup + N 2...
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