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Posts posted by Horza2002

  1. The final step can be done, but you need to add some other reagents in there. What is the inital product when an amine reacts with a carbonyl?


    Additionally, there is a possible alteration of your method that will get you from the 2-amino toluene (number 2) all the way to your benzyl alcohol (number 5) in a single step. Think about the position you are trying to oxidise and what reagents are out there to do this transformation (HINT: its a p-block element based reagent)

  2. This reaction will be very difficult to do. The problem arises because the initally formed monoalkylated product is more nucleophilic that the start material (due to the alkly chain electron donating properties). What you are probably ending up with is the quaternary nitrogen salts resulting from another subsitution of the alkly iodide.


    If I were you, I would stop trying to do this and try a reductive amination (using the corrossonding aldehyde and sodium cyanoborohydride) and the monoprotected piperazine. That way you will only get the product you want without any over alkyation reactions.

  3. ...it is not a nitrating agent at all. For one thing, there is no nitro group in it! Sulphuric acid is used to protonate nitric acid which then decomposes to NO2+ which is the actual nitrating species. And I really wouldn't call is the "best". Ever tried nitrating anything with this method? You end up with a mixture of all possible regioisomers that are often next to impossible to seperate.

  4. Hi there,


    I think there is an inherant problem with this reaction. When undergraduates are taught about making amines, the first thing you are told is that you can't make them from alkyating a NH2...the monoalkylated nitrogen is more reactive than the unalkylated nitrogen due to the electron donating properties of the alkly chain. I would expected that you would eventually end up the the tetraalkylated amine instead of your desired monoalkayted.


    Additionally, if you add to strong a base to this reaction, you will deprotonate the Boc N-H (it is rather acidic due to the electron withdrawing properties of the adjacent carbonyl). If that happens, then you are going to end up alkyating the wrong nitrogen atom.


    You could potentially make the dianion (deprotonate the Boc nitrogen and the NH2) with two equivalents of BuLi and then try adding one equiv of the iodide, but I expect you will get cylisation and a mixture of products.


    The main issue with this reaction is the diiodide...is it essential that you do this? If not, then I would suggest adding a few more steps into the scheme and introduce the second iodide after you have alkylated the hydrazine

  5. Yes it will work because I have done this in our lab. We have done it on a number of enzymes and a number of natural product analogues to aid in their purification. As in the link, a click reaction is usually used to introduce the biotin linker to the substrate/enzyme of interest as it is very easy to do.


    There are several limitations to this procedure though. Binding of the biotinaylted substrate is not always easy. We found that the larger the substrate you try to trap, the harder it is to bind. In addition to this, you need to use alot of biotin to elute your trapped substrate from the strepavidine column. Commerical biotin is really really expensive at the moment and so doing this on a large scale is not really practical. It is possible to overproduce biotin from microorganism and purify it, but this is a very lengthy and time consuming process.

  6. We have cellophane discs in our lab which we use to grow Streptomyces bacteria on so they don't grow into the agar. This allows all small molecules to pass through them, but not bacteria cells. Any good?

  7. I think thats a mistake. A to D is fine, and OsO4 is a well known reagent for the formation of cis-1,2-diols...and D and E are isomers of each other so thats fine (do you know what type of isomers they are of each other?). However, you don't get the diketone product, you only get the diol.

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