Guest viewing limit reached
  • You have reached the maximum number of guest views allowed
  • Please register below to remove this limitation

17a hydroxy-pregna-1 4-diene-3 20-dione

Patrick Arnold said:
that may acheive side chain clevage to give the latter compound. i am not sure
Click to expand...
What side chain?

I know it's apparently a stronger oxidant than KMnO4, I just don't think it exhibits SET behavior. You'd probably have MUCH better luck using Nicolaou's IBX protocol... IDK, say, 4eq IBX in DMSO, 2d at 80*C inside the vessel ought to do the trick ;)
 
the pregnane side chain.

it usually requires previous reduction of the 20-keto group though

we have done this before. we were trying to make 4-dhea starting from 17a-hydroxyprogesterone at one time. lead tetraacetete worked better, but the amount of lead left in the final product was troubling
 
Beejis60 said:
What side chain?

I know it's apparently a stronger oxidant than KMnO4, I just don't think it exhibits SET behavior. You'd probably have MUCH better luck using Nicolaou's IBX protocol... IDK, say, 4eq IBX in DMSO, 2d at 80*C inside the vessel ought to do the trick ;)
Click to expand...


IBX unfortunately tends to cause dehydrogenation reactions. u would end up with a considerable amount of 4,6
 
Patrick Arnold said:
the pregnane side chain.

it usually requires previous reduction of the 20-keto group though

we have done this before. we were trying to make 4-dhea starting from 17a-hydroxyprogesterone at one time. lead tetraacetete worked better, but the amount of lead left in the final product was troubling
Click to expand...

Wasn't he talking about from androstenedione? Amihigh?

Patrick Arnold said:
IBX unfortunately tends to cause dehydrogenation reactions. u would end up with a considerable amount of 4,6
Click to expand...

Not with androstenedione as an SM... or even androstanedione ;) JACS, 2002, 124(10), 2245. I've memorized all the Nicolaou/Baran IBX papers. This one is a particularly tricky reaction, but doable.

Patrick Arnold said:
u should try to find a copy of carl djreassi's "steroid reactions" beejis
Click to expand...

three american dollars plus shipping? I'll take two.
 
Beejis60 said:
Not with androstenedione as an SM... or even androstanedione ;) JACS, 2002, 124(10), 2245. I've memorized all the Nicolaou/Baran IBX papers. This one is a particularly tricky reaction, but doable.


.
Click to expand...

U do recall that IBX in dmso was the method we used to make 1-ad (first step)

It was a very nice reaction. It would give small amounts of 4-dione and 1,4-dione as side products though.

It was much easier than the way we first made the product, which involved a bromination step followed by a debromination step
 
Patrick Arnold said:
U do recall that IBX in dmso was the method we used to make 1-ad (first step)

It was a very nice reaction. It would give small amounts of 4-dione and 1,4-dione as side products though.

It was much easier than the way we first made the product, which involved a bromination step followed by a debromination step
Click to expand...

At longer temps and a twat hair of water to initiate the 'enol' IBX form, conversion of androstanedione and androstenedione proceeds nicely to boldione. I guess I missed whatever you were talking about. Don't think I've ever seen anyone use bismuthate for oxidative cleavage though. Phil Baran blows out the 17-side chain of prednisone (similar steroidal structure to OHP) with NaIO4 quite nicely in his synthesis of Cortistatin A.
 
Beejis60 said:
At longer temps and a twat hair of water to initiate the 'enol' IBX form, conversion of androstanedione and androstenedione proceeds nicely to boldione. I guess I missed whatever you were talking about. Don't think I've ever seen anyone use bismuthate for oxidative cleavage though. Phil Baran blows out the 17-side chain of prednisone (similar steroidal structure to OHP) with NaIO4 quite nicely in his synthesis of Cortistatin A.
Click to expand...

there is a whole section on conversion of 20-ketosteroids to 17-ketosteroids in the djerassi book i mentioned.

we used jones reagent in acetone to make the adrenosterone from hydrocortisone. If cortisone were commercially available we could have used a milder oxidizing reagent
 
Interesting that Jones Ox cleaves that side chain. Probably a bit cheaper than IBX but probably not as 'innocuous' as NaIO4. Can't imagine a ton of con. H2SO4 and CrO3 being cheap, safe, and "green". The workup of Jones Ox is beautiful though.
Ordered that book at a solid $3.35. Gonna be my 2nd favorite book behind Dehydrobenzene and Cycloalkynes by Hoffmann.
 
You must log in or register to reply here.
Back
Top