Hive Novel Discourse

	Main Index Search Register Login Who's Online FAQ Links
	Main Index Search Register Login Who's Online FAQ Links

	2 Online, 0 Active		You are not logged in

This is a historical archiveThe forum is read-only. Private information has been removed. It is not possible to login.

	Novel Discourse

All 9 posts Subject: Arylboronic acids for Suzuki Couplings Please login to post Down

Rhodium
(Chief Bee)
05-18-03 17:37
No 433965
User Picture       Arylboronic acids for Suzuki Couplings
(Rated as: excellent)

Arylboronic acids [Ar-B(OH)₂] are very useful precursors used in Pd-catalyzed Suzuki Couplings, where almost any organic halide can be coupled with an arylboronic acid, one example being that allyl bromide would give allylbenzenes.

General procedure for arylboronic acid synthesis¹

Magnesium turnings (30 mmol) were placed in a round-bottomed flask and then flame-dried under N₂. Aryl bromide (30 mmol) dissolved in THF (20 mL) was added with an addition funnel to the flask slowly. The reaction mixture was gently refluxed for 3 to 4 h. After cooling, the Grignard reagent was transferred to a solution of (CH₃O)₃B in THF (10 mL) at -78°C and stirred overnight while warming up to RT slowly. After acidification with 10% HCl (10 mL), the product was extracted into ether (3x100 mL) and dried (sodium sulfate). The solvent was then removed under reduced pressure, and the products was precipitated by hexane with further recrystallization from water.

p-Tolylboronic acid: white needles were obtained in 81% yield; mp 243-244°C (lit.² 242-243°C).

p-Methoxyphenylboronic acid: White needles were obtained in 72% yield; mp 197-198°C (lit.² 202-205°C).

Arylboronic Acid References:

[1]: Tetrahedron 51(11), 3129 (1995)
[2]: J. Am. Chem. Soc. 53, 711 (1931)

Suzuki Coupling

In this reaction is a bromo compound R-Br coupled to a boronic acid R'-B(OH)2 with Pd-catalyst. In the first step the bromo compound is added oxidative at Pd(0) and the bomide is metathetically substituted by an hydroxy ion. After trans-metallation and secession of tetrahydroxyborate the Pd(II) with both organic moieties is obtained. The Pd is reductively eliminated and the residues coupled to R-R'.

Suzuki Coupling References:

http://themerckindex.cambridgesoft.com/TheMerckIndex/NameReactions/ONR388.htm
http://www.chempensoftware.com/reactions/rxn566.htm
http://www.mdpi.net/ecsoc-5/e0029/e0029.htm
http://www.sigmaaldrich.com/img/assets/3460/al_arylboronic_acids.pdf

Aurelius
(Hive Addict)
05-20-03 00:30
No 434235
      Protected amines

why not just use the protected aminoalkylhalide to directly produce amphetamine or meth?

Barium
(Hive Addict)
05-20-03 09:49
No 434305
      Suzuki catalysts

These catalysts are recomended by the catalyst manufacturers;

trans-PdCl₂(CH₃CN)₂
Pd(PPh₃)₄
Bedford's acetate
Bedford's chloride
[Pd(OAc)₂]₃

Polymer supported Pd(PPh₃)₄ is used in the industry today because it has the advantages of a heterogenous catalysts (easy removal by filtration) combined with the properties of the homogenous catalyst (better utilisisation of the metal, elimination of in-pore diffusion, easy exotherm control).

Freaky

Rhodium
(Chief Bee)
05-20-03 20:48
No 434390
User Picture       Suzuki Phenethylamines

why not just use the protected aminoalkylhalide to directly produce amphetamine or meth?

That is of course possible, I didn't mention any such halide specifically, as I am not 100% sure exactly which protecting groups are compatible with Suzuki Chemistry. Also, allylbromide given as example in my post has a history of giving very high yields in coupling reactions, while other more complex halides may have unpredictable yields.

Aurelius
(Hive Addict)
05-20-03 21:03
No 434393
      Yields

Good point on the yields comment. However, what kind of yields could be acheived overall through each route? Do you have any more references for this type of coupling?

Rhodium
(Chief Bee)
05-20-03 22:11
No 434400
User Picture       Suzuki Cross-coupling References

Suzuki couplings can be close to quantitative in some cases (where degassed solvents, inert atmosphere, fancy Pd ligands and reactive substrates are used), but expect good yields, as in 75%+ or so for non-problematic substrates.

Below are two Suzuki couplings I have posted here earlier, I'm sure you can find more using TFSE, and if you search for "suzuki coupling" or "suzuki reaction" using Google, you'll find a lot of articles on the topic.

Post 320892 (Rhodium: "Allylbenzenes by Suzuki Coupling", Novel Discourse)
Post 405016 (Rhodium: "Pd-catalyzed Suzuki synth of phenylacetamides", Novel Discourse)

Aurelius
(Hive Addict)
05-21-03 04:10
No 434490
      Thanks

Just so you know, I wasn't trying to opt-out on using the search engine. The reason I asked is that it's easier to find materials relevant to our cause if I ask you first. The articles in general I can find pretty easily.

Thanks for the help though- very informative.

Rhodium
(Chief Bee)
05-21-03 11:58
No 434536
User Picture       Suzuki Chemistry Reviews
(Rated as: excellent)

No hard feelings, I merely thought that you might find more info on google than from me, my palladium coupling chem knowledge could be a lot better than it is.

I found a few review articles about Suzuki Chemistry today:

Chem. Rev. 95, 2457 (1995) (https://www.rhodium.ws/pdf/pd-cat.cross-coupling.organoborons.pdf)
J. Organomet. Chem. 576, 147 (1999) (https://www.rhodium.ws/pdf/suzuki.cross-coupling.review.1995-1998.pdf)
Chem. Rev. 102, 1359 (2002) (https://www.rhodium.ws/pdf/aryl-aryl.bond-formation.pdf)

Aurelius
(Hive Addict)
05-21-03 20:44
No 434612
      Chemistry

Don't worry about offense, I take all of your comments seriously as you have nothing to prove to me. (My knowledge of chemistry in general could use some work.)

And thanks! those are great links.

	https://the-hive.archive.erowid.org	the-hive@erowid.org



Powered by Nihilism v.3.02.5, (C) 2015. All rights reserved.
Links Erowid Rhodium

	All 9 posts		Subject: Arylboronic acids for Suzuki Couplings		Please login to post		Down


		Rhodium (Chief Bee) 05-18-03 17:37 No 433965				Arylboronic acids for Suzuki Couplings (Rated as: excellent)
						Arylboronic acids [Ar-B(OH)₂] are very useful precursors used in Pd-catalyzed Suzuki Couplings, where almost any organic halide can be coupled with an arylboronic acid, one example being that allyl bromide would give allylbenzenes. General procedure for arylboronic acid synthesis¹ Magnesium turnings (30 mmol) were placed in a round-bottomed flask and then flame-dried under N₂. Aryl bromide (30 mmol) dissolved in THF (20 mL) was added with an addition funnel to the flask slowly. The reaction mixture was gently refluxed for 3 to 4 h. After cooling, the Grignard reagent was transferred to a solution of (CH₃O)₃B in THF (10 mL) at -78°C and stirred overnight while warming up to RT slowly. After acidification with 10% HCl (10 mL), the product was extracted into ether (3x100 mL) and dried (sodium sulfate). The solvent was then removed under reduced pressure, and the products was precipitated by hexane with further recrystallization from water. p-Tolylboronic acid: white needles were obtained in 81% yield; mp 243-244°C (lit.² 242-243°C). p-Methoxyphenylboronic acid: White needles were obtained in 72% yield; mp 197-198°C (lit.² 202-205°C). Arylboronic Acid References: [1]: Tetrahedron 51(11), 3129 (1995) [2]: J. Am. Chem. Soc. 53, 711 (1931) Suzuki Coupling In this reaction is a bromo compound R-Br coupled to a boronic acid R'-B(OH)2 with Pd-catalyst. In the first step the bromo compound is added oxidative at Pd(0) and the bomide is metathetically substituted by an hydroxy ion. After trans-metallation and secession of tetrahydroxyborate the Pd(II) with both organic moieties is obtained. The Pd is reductively eliminated and the residues coupled to R-R'. Suzuki Coupling References: http://themerckindex.cambridgesoft.com/TheMerckIndex/NameReactions/ONR388.htm http://www.chempensoftware.com/reactions/rxn566.htm http://www.mdpi.net/ecsoc-5/e0029/e0029.htm http://www.sigmaaldrich.com/img/assets/3460/al_arylboronic_acids.pdf



		Aurelius (Hive Addict) 05-20-03 00:30 No 434235				Protected amines
						why not just use the protected aminoalkylhalide to directly produce amphetamine or meth?



		Barium (Hive Addict) 05-20-03 09:49 No 434305				Suzuki catalysts
						These catalysts are recomended by the catalyst manufacturers; trans-PdCl₂(CH₃CN)₂ Pd(PPh₃)₄ Bedford's acetate Bedford's chloride [Pd(OAc)₂]₃ Polymer supported Pd(PPh₃)₄ is used in the industry today because it has the advantages of a heterogenous catalysts (easy removal by filtration) combined with the properties of the homogenous catalyst (better utilisisation of the metal, elimination of in-pore diffusion, easy exotherm control). Freaky



		Rhodium (Chief Bee) 05-20-03 20:48 No 434390				Suzuki Phenethylamines
						why not just use the protected aminoalkylhalide to directly produce amphetamine or meth? That is of course possible, I didn't mention any such halide specifically, as I am not 100% sure exactly which protecting groups are compatible with Suzuki Chemistry. Also, allylbromide given as example in my post has a history of giving very high yields in coupling reactions, while other more complex halides may have unpredictable yields.



		Aurelius (Hive Addict) 05-20-03 21:03 No 434393				Yields
						Good point on the yields comment. However, what kind of yields could be acheived overall through each route? Do you have any more references for this type of coupling?



		Rhodium (Chief Bee) 05-20-03 22:11 No 434400				Suzuki Cross-coupling References
						Suzuki couplings can be close to quantitative in some cases (where degassed solvents, inert atmosphere, fancy Pd ligands and reactive substrates are used), but expect good yields, as in 75%+ or so for non-problematic substrates. Below are two Suzuki couplings I have posted here earlier, I'm sure you can find more using TFSE, and if you search for "suzuki coupling" or "suzuki reaction" using Google, you'll find a lot of articles on the topic. Post 320892 (Rhodium: "Allylbenzenes by Suzuki Coupling", Novel Discourse) Post 405016 (Rhodium: "Pd-catalyzed Suzuki synth of phenylacetamides", Novel Discourse)



		Aurelius (Hive Addict) 05-21-03 04:10 No 434490				Thanks
						Just so you know, I wasn't trying to opt-out on using the search engine. The reason I asked is that it's easier to find materials relevant to our cause if I ask you first. The articles in general I can find pretty easily. Thanks for the help though- very informative.



		Rhodium (Chief Bee) 05-21-03 11:58 No 434536				Suzuki Chemistry Reviews (Rated as: excellent)
						No hard feelings, I merely thought that you might find more info on google than from me, my palladium coupling chem knowledge could be a lot better than it is. I found a few review articles about Suzuki Chemistry today: Chem. Rev. 95, 2457 (1995) (https://www.rhodium.ws/pdf/pd-cat.cross-coupling.organoborons.pdf) J. Organomet. Chem. 576, 147 (1999) (https://www.rhodium.ws/pdf/suzuki.cross-coupling.review.1995-1998.pdf) Chem. Rev. 102, 1359 (2002) (https://www.rhodium.ws/pdf/aryl-aryl.bond-formation.pdf)



		Aurelius (Hive Addict) 05-21-03 20:44 No 434612				Chemistry
						Don't worry about offense, I take all of your comments seriously as you have nothing to prove to me. (My knowledge of chemistry in general could use some work.) And thanks! those are great links.

All 9 posts	End of thread	Top