Recently one of my relatives have fallen ill and was prescribed with some colchicine. Looking at the structure of the molecule, and with nothing much to do, I decided to put my retrosynthetic skills to the test. Here is a picture of my thought process: enter image description here

Is there a better way to design a synthesis for this compound using the disconnection method.

From 11b, a Birch reduction is carried out to give the qunione 10b. A rearrangement of the ketone with methanediazonium gives 9b. A dihydroxylation with a peroxy acid and subsequent addition of water gives 8b. A double dehydration reaction with sulfuric acid, coupled with the protection of the ketone with propan-1,3-diol gives the seven-membered quinone 7b. A Heck reaction (or Ullmann reaction) with 7a with a palladium catalyst yields 6. (The protection group is thereafter labelled "PG") Friedel-Crafts acylation with ethanoyl chloride yields 5 (although on second thoughts, I should have done the acylation from 7a from the start). A Michael addition is then carried out with $\ce{BuLi}$ to lithiate the ketone to give the terminal imine 4. Since this terminal imine is unstable, a mild reducing agent converts the imine to the amine 3. The ketone is then removed by addition of dithiol and subsequently reduced by Raney nickel to form 2. Finally, a simple condensation reaction between the amine and acetic anhydride, followed by deprotection of the ketone using an acid, yields the final product colchicine, 1.


closed as too broad by ringo, Todd Minehardt, Klaus-Dieter Warzecha, bon, NotEvans. Feb 1 '17 at 8:54

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ While this is an interesting question I have to agree that it is too broad. Maybe focus on a specific aspect of the synthesis or head over to the chat to discuss your question in more detail. $\endgroup$ – bon Feb 1 '17 at 8:26

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