Amide Bond Formation Using HATU

April 1st, 2007

 

The carboxylic acid (500 mg, 1.59 mmol) was dissolved in 15 mL of dry DMF with stirring. O-(7-Azabenzotriazole-1-yl)-N,N,N,N’-tetramethyluronium hexafluorophosphate (HATU, 665 mg, 1.75 mmol) was added as a solid and the resulting clear solution was stirred for 10 min at room temperature. N-Boc-ethylenediamine (0.5 mL, 3.2 mmol) was injected and the resulting yellow solution was stirred for 20 min before 0.8 mL (4.6 mmol) of diisopropylethylamine (DIEA) was added by syringe. The mixture was stirred for 16 h at room temperature, at which point 150 mL of a saturated solution of NaCl was added. The mixture was cooled to 4 °C and the white precipitate was isolated by vacuum filtration over sintered glass and washed with 100 mL of deionized water. Yield 695 mg (1.5 mmol, 96%). White powder. 1H NMR (400 MHz, DMSO-d6): 8.44 (t, J = 6.0, 1H), 7.83 (t, J = 4.9, 1H), 7.74 (d, J = 8.0, 2H), 7.38 (d, J = 8.0, 2H), 7.30 (s, 2H), 6.79 (t, J = 5.3, 1H), 4.28 (d, J = 5.9, 2H), 3.02 (m, 2H), 2.93 (m, 2H), 2.12 (t, J = 6.6, 2H), 2.03 (t, J = 6.6, 2H), 1.46 (m, 4H), 1.35 (s, 9H). 13C NMR(101 MHz, DMSO-d6): 172.84, 172.79, 156.29, 144.55, 143.22, 128.12, 126.35, 78.31, 42.32, 40.78, 39.33, 35.84, 35.78, 28.92, 25.62 (the signals from the two central adipoyl methylene carbons appear to be accidentally equivalent). High Resolution ESI-MS: 457.2118. Calculated for C20H33N4O6S+ [M+H+]: 457.2115.

Notes: Ordinarily, I hesitate to use HATU because it is so freaking expensive. That said, the stuff is magical. I tried this reaction a number of times with EDC HCl and got miserable yields. The first shot with HATU gave 96%—my best yield ever for amide formation.

If you would like a citation for this procedure, here is the paper where we published it. (Check out page S8 of the Supporting Information file in Krishnamurty, et al. J. Am. Chem. Soc., 2007, 129, 1312-1320.)

Previous Comments

  1. milkshake Says:
    April 1st, 2007 at 4:21 am HATU is a pretty darn good coupling reagent but you have to watch out with free amino groups and even with some hydroxys – it likes to guanylate them unless it has enough carboxylic acid around.The reason why HATU is so expensive is that Carpino patented his stuff and then sold the patents to some company (I think it is a part of Celera empire now) and the company has monopoly so it likes to price the product as high as the market will bear. The same problems as with TFFH. TFFH is easy to make but I don’t know if I would like to mess with synthesizing hydroxyazabenztriazole (the rest of the preparation is relatively easy).
  2. Wolfie Says:
    April 1st, 2007 at 11:22 pm As you know, Paul, EDC alone is bad because it produces so many side reactions. Taking a large excess of EDC versus your reactant and an even larger excess of NHS (several complicated reasons involved in that) gives almost quantitative conversion of your carboxylic acid to the NHS ester. Now, if you take an excess of your amine that is once again large enough, you get 100 % of your carboxylic acid back as an amide, guaranteed (unless your workup is not perfect, but how could it be).But why should any chemist want to take an excess of anything ? Given that we perfect chemists should constantly try to optimize ourselves, we want to have the following reaction conditions:reactant 1 / reactant 2 / reagent = 1 : 1 : 1, temperature = 25 degrees, reaction time = 5 minutes, yield = 101%take an excess all the time, and your neighbour will be fine

    the greatest poet of all

  3. Paul Says:
    April 1st, 2007 at 11:30 pm Yeah, I tried a number of variations with EDC, including adding N-hydroxy compounds and tertiary amines. NHS didn’t do much for my yield. I don’t know why.
  4. milkshake Says:
    April 1st, 2007 at 11:33 pm wolfie, you are talking out of your ass, as usual. Hydroxyazabenztriazole esters are incomparably faster-coupling than activated esters made from HOSu or HOBt. I have made isolated, purified activated esters from all three, many times.
  5. Wolfie Says:
    April 1st, 2007 at 11:44 pm standards are not good enough for you, you need perfect reactions, such as HATUbut I see your excesses were quite acceptable (1.59 : 1.75 : 3.2), so I don’t know either why the NHS did not do it. Did the sulfone perhaps oxidise anything ?
  6. Wolfie Says:
    April 1st, 2007 at 11:47 pm Milkshake, as you know, at least in theory, faster coupling (= kinetics) does not equal higher final yield (= thermodynamic equilibrium)the right excess of the right stuff always leads to the right goal
  7. Paul Says:
    April 1st, 2007 at 11:55 pm There was a lot of starting material left over. My main concern was not the yield as much as the purification. I only needed something on the order of hundreds of milligrams of the product, but I didn’t want to have to run a column because these compounds streaked all over the place. The worst part of the EDC reaction giving a low yield (aside from the embarrassment of reporting an awful yield with a seemingly easy reaction) was that I’d have to find a way to get rid of all the other crap. After the initial “standard” EDC defeat, I set up four or five vials using different reagents, then picked the one that worked best. I really wasn’t in the mood to reinvent the wheel.
  8. Wolfie Says:
    April 2nd, 2007 at 12:01 am Does HATU also work in aqueous medium ? If yes, how long are the activated carboxylic acids stable at an acceptable pH, say 5 – 8, so I can rinse away all the excess reagents before coupling of my amino-functionalized peptide ?very serious, of course I could look it all up in google
  9. mederic Says:
    April 2nd, 2007 at 1:27 am The price of HATU/HOAt is extortionate, I used to get by with bog standard HBTU/HOBt/Hunigs for my couplings.HATU was reserved for only the most important reactions, even nearly working as well as DPPA for some macrocyclisations.Top reagent.
  10. Kyle Finchsigmate Says:
    April 2nd, 2007 at 5:09 pm HATU vs. PyBOP. Who would win in a coupling fight?
  11. European Chemist Says:
    April 2nd, 2007 at 6:16 pm I say, wouldn’t this justify us writing a review about peptide coupling reagents, from the blogger/practitioner’s point of view?
    I for one must say that if I had to run such a reaction, I’d probably either spend 1 week just trying to figure how many reagents are available (and failing to retrieve more than 60% of the total) or jump into the first one that is available in the lab stock. Which of these would be the best??…..
  12. mederic Says:
    April 2nd, 2007 at 6:33 pm #10,HATU vs PyBrOP, surely?I thought BrOP beat BOP.:-)
  13. Phlogiston Says:
    April 3rd, 2007 at 2:19 pm HATU is by far the fastest coupling agent. The patent is almost over on it in the U.S., so the price will drop as it is dirt cheap overseas (ask around China). It is also quite water tolerant, e.g. your solvent can be very wet during coupling.
  14. Wolfie Says:
    April 3rd, 2007 at 9:40 pm Quite water tolerant is of course no valid answer. I wanted to know : are the activated carboxylic acids stable for at least some hours at a pH between 5 and 8 ? I guess, they are not, since you say it’s so fast, so I will stay with my NHS/EDC.
  15. Phlogiston Says:
    April 4th, 2007 at 11:24 am ^Try it and find out. HATU rocks
  16. Wolfie Says:
    April 5th, 2007 at 7:20 pm Thinking still comes before trying in Chemistry. If all you guys say it’s fast, it’s probably too fast for me.I should go to the library and do a good literature search, but why do we need this when we have google (or a blog).
  17. ChemBark » Blog Archive » Chemical Search Traffic Says:
    May 7th, 2007 at 4:50 am […] That said, I have tried to make an effort to incorporate more type-I material here. Back on April Fools’ Day, I posted three synthetic procedures as a homage to the great Org Prep Daily: amide coupling using HATU, methyl ester hydrolysis using LiOH, and a porphyrin preparation based on the work of J.S. Lindsey. That day saw some of the heaviest traffic in the history of ChemBark, and in the subsequent month, this site has gotten a significant number of hits (well over 100) based on searches directly related to these reactions. In fact, ChemBark comes up on the first page of results when you google “HATU”, “amide bond formation”, “methyl ester deprotection”, or “porphyrin synthesis”. […]
  18. Flopp Says:
    July 17th, 2007 at 5:11 pm Does anyone have any experience with HATU vs. TBTU?
  19. Milkshake Says:
    July 17th, 2007 at 5:22 pm HATU is more powerful and more expensive. It is used in cases where other stuff fails. You can use HBTU, TBTU, BOP etc just as well if you can live with longer reaction times. Please note that with uronium based reagents (HATU, TBTU, HBTU) one should preactivate the acid with the reagent and 2-3 equivs of iPrNEt for about 30 min – before throwing in the R2NH coupling partner. Also, dimethyl acetamine is one of the best solvents for coupling but dimethylamine-free (non-fishy, oily-smeling) DMF is fine so is DCM, chloroform or MeCN as a solvent if your material dissolves in it.
  20. Flopp Says:
    July 24th, 2007 at 8:21 pm WolfieIt looks like TSTU and TNTU as well as DPTF. See Tetrahedron 2004, 2447-2467.
  21. FemaleChemist Says:
    September 18th, 2007 at 2:13 pm I just read your interesting conversation about HATU. I currently used HBTU to couple some carboxylic acids to oligos, the conditions are: xs HBTU, xs DIEA, DMF, 1 hour. It works very well but I’d like to reduce the coupling time. I believe that HBTU will do that? Can I keep the same conditions (DMF, DIEA)? I assume so…
  22. Andres Says:
    October 4th, 2007 at 1:38 am Hi Paul,When you have troubles with EDC alone, the next step is to try EDC/HOBt method “cooH 1eq, RNH2 1.2eq, EDC 1.5eq, HOBt 1.5eq, DIPEA 3eq, in DCM at rt for 3-12hours” which is a stronger activating method. If it does not work then you may try HBTU coupling.good luck

4 Responses to “Amide Bond Formation Using HATU”

  1. tushar Says:

    any experience of hatu copluing with substituted amino thiazoles i am getting very low yields.

  2. Paul Bracher Says:

    It’s amazing that this post is one of the most blog’s most popular in terms of page views. (Being on the first page of hits for a Google search of “HATU” is probably the only reason why.)

    For those interested in having a citation, I added a link to the paper at the end of the post. The HATU coupling procedure is on page S8 of the Supplementary Info file.

    My contributions to this project were purely in the synthesis of some of the compounds studied, and I am proud that my hatred of columns led to the attempt of running everything in DMF then crashing out the product by adding water. It’s nice when things work.

  3. hans_peptide Says:

    You do mean boc ethyl amine ? I don’t see a diamine ! Dr. Hans Peptide

  4. CFS Says:

    Hey guys, out of curiosity/naiveness why does aeveryone perorm this reactions at room temerature for long time. Could they be perform at higher temperature and shorter times?


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