Comments on: Functional Group Tolerance/Protecting Group Strategy http://allthingsmetathesis.com/functional-group-toleranceprotecting-group-strategy/ Tue, 10 Apr 2012 12:58:05 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Ajay http://allthingsmetathesis.com/functional-group-toleranceprotecting-group-strategy/comment-page-1/#comment-2868 Ajay Tue, 18 Oct 2011 15:38:08 +0000 http://allthingsmetathesis.com/?p=1415#comment-2868 Are phenols tolerated in a cross-metathesis reaction or do they have to be protected? For example will 2-allylphenol react in a cross metathesis reaction efficiently? Any suggestions and or references would be great. Thanks. Are phenols tolerated in a cross-metathesis reaction or do they have to be protected? For example will 2-allylphenol react in a cross metathesis reaction efficiently? Any suggestions and or references would be great. Thanks.

]]> By: hubcapsignstop http://allthingsmetathesis.com/functional-group-toleranceprotecting-group-strategy/comment-page-1/#comment-141 hubcapsignstop Wed, 17 Feb 2010 06:20:29 +0000 http://allthingsmetathesis.com/?p=1415#comment-141 thanks alot, i may be trying bis- and tris-TFA salts. Just wondering; are there any relatively polar solvents/solvent mixtures that are compatible with Grubbs carbene that I am unaware of and used at least semi-regularly? (I have honestly never ventured outside of DCM/DCE/PhMe) Milkshake (nice blog): (I have personally not had any problem with amides), amines are typically nightmarish-though compatible with Schrock apparently) as for the Lewis acids: i have had mild success with LiCl. But my favorite is Ti(OiPr)4. Results varied widely based on my substrate, but catalyst activity was no longer the problem. I know the Ti acid has been used to disrupt stable chelates in the lit (4-pentenoate-derived dienes, etc) but it seems to work to occupy all sorts of electron-rich metathesis suppressors. other functional groups I have had trouble with using Grubbs carbene: N-allyl (sometimes gets ripped off-and isomerization suppressors idnt work for me) vinyl ethers (e-rich alkene; need Schrock) thanks alot,
i may be trying bis- and tris-TFA salts. Just wondering; are there any relatively polar solvents/solvent mixtures that are compatible with Grubbs carbene that I am unaware of and used at least semi-regularly? (I have honestly never ventured outside of DCM/DCE/PhMe)

Milkshake (nice blog):
(I have personally not had any problem with amides), amines are typically nightmarish-though compatible with Schrock apparently)
as for the Lewis acids:
i have had mild success with LiCl. But my favorite is Ti(OiPr)4. Results varied widely based on my substrate, but catalyst activity was no longer the problem. I know the Ti acid has been used to disrupt stable chelates in the lit (4-pentenoate-derived dienes, etc) but it seems to work to occupy all sorts of electron-rich metathesis suppressors.

other functional groups I have had trouble with using Grubbs carbene:
N-allyl (sometimes gets ripped off-and isomerization suppressors idnt work for me)
vinyl ethers (e-rich alkene; need Schrock)

]]> By: nickel http://allthingsmetathesis.com/functional-group-toleranceprotecting-group-strategy/comment-page-1/#comment-140 nickel Wed, 17 Feb 2010 02:03:10 +0000 http://allthingsmetathesis.com/?p=1415#comment-140 A thing like solubility is hard to generalize, but in my experience, HCl salts are soluble (or at least soluble enough) in DCM to allow for reaction. A thing like solubility is hard to generalize, but in my experience, HCl salts are soluble (or at least soluble enough) in DCM to allow for reaction.

]]> By: milkshake http://allthingsmetathesis.com/functional-group-toleranceprotecting-group-strategy/comment-page-1/#comment-139 milkshake Wed, 17 Feb 2010 01:52:02 +0000 http://allthingsmetathesis.com/?p=1415#comment-139 I suppose a TFA salt should be fairly soluble in DCM. Also you can do a greasy non-coordinating salt like hexafluorophosphate or tetrafluoroborate. Even damned camphorsulphonates are quite soluble in organics - depending on the amine. I suppose a TFA salt should be fairly soluble in DCM. Also you can do a greasy non-coordinating salt like hexafluorophosphate or tetrafluoroborate. Even damned camphorsulphonates are quite soluble in organics – depending on the amine.

]]> By: hubcapsignstop http://allthingsmetathesis.com/functional-group-toleranceprotecting-group-strategy/comment-page-1/#comment-138 hubcapsignstop Sun, 14 Feb 2010 00:01:07 +0000 http://allthingsmetathesis.com/?p=1415#comment-138 If doing metathesis on an amine salt, what would a good solvent compatible with a Grubbs carbene be? (presumably the salt is insoluble in DCM, etc...) If doing metathesis on an amine salt, what would a good solvent compatible with a Grubbs carbene be? (presumably the salt is insoluble in DCM, etc…)

]]> By: milkshake http://allthingsmetathesis.com/functional-group-toleranceprotecting-group-strategy/comment-page-1/#comment-137 milkshake Sat, 13 Feb 2010 01:43:10 +0000 http://allthingsmetathesis.com/?p=1415#comment-137 amides are pretty Lewis-basic on carbonyl (thats why DMF is such a great solvent). I remember that people who did metathesis on molecules with amide bonds complained about the deactivation - they needed to heat alot to get turnover and then they had catalyst decomposition problem under these conditions. I wonder if some suitable Lewis acid like BF3 etherate or perhaps a lithium salt added in stoechiometric quantity could take care of this problem. Do you know if some Lewis acids are compatible with Ru metathesis catalysts? amides are pretty Lewis-basic on carbonyl (thats why DMF is such a great solvent). I remember that people who did metathesis on molecules with amide bonds complained about the deactivation – they needed to heat alot to get turnover and then they had catalyst decomposition problem under these conditions. I wonder if some suitable Lewis acid like BF3 etherate or perhaps a lithium salt added in stoechiometric quantity could take care of this problem. Do you know if some Lewis acids are compatible with Ru metathesis catalysts?

]]>