jon
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direct hydroamination of olefins with biscyclopentadiene samarium complex catalysis
you guys especially you bees out there might be interested in the possibilty of adding primary amines directly to olefins via cp2Sm catalysts the link
to the patent is here:
http://www.google.com/patents?id=lhkbAAAAEBAJ&printsec=d...
first thing comes to mind is mdma but i can imagine you can have a lot of fun, and little fuss with this route any thoughts?
oh yeah, yeilds are stellar from what i read too like 95%
these examples use allyl amines and use this catalyst to effect cyclization.
the caveat being that olefins can be hydraomainated in very high yeilds the solvents used are typically hydrocarbons like toulene cylcohexane, etc.
the reaction conditions are anhydrous the catalyst seems to have a high turnover rate as 1/100 ratios are employed
the catalyst i believe is made from samarium and cyclopentadiene in thf and then puified by vacum sublimation.
a lot of interesting compounds can be made by this simple process just about any of the substituted allybenzenes could therorectically be aminated
this way.
this could be a definite breakthrough.
[Edited on 15-12-2008 by jon]
[Edited on 15-12-2008 by jon]
[Edited on 15-12-2008 by jon]
[Edited on 15-12-2008 by jon]
[Edited on 15-12-2008 by jon]
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stoichiometric_steve
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| Quote: | Originally posted by jon
first thing comes to mind is mdma but i can imagine you can have a lot of fun, and little fuss with this route any thoughts? |
you apparently didnt read the patent.
this stuff is not "new" - and little fuss is something else. glovebox, schlenk technique, highvac lines etc. definitely nothing the average E cook
would be able to afford or bother with.
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jon
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yeah you're sure right about that the solvents have to be degassed to avoid poisoning the catalyst, everthing has to be scrupulously dried three times
over sodium potassium and mol seieves.
arogon/nitrogen atmosphere a lot of fuss is an understatement.
there is one idea i threw out there some time ago cesium promoted mono alkylation of primary amines as well as cesium suppressed "overalkylation"
basically in a system where you have bromoalkane mol equivalent of cesium base (carbonate or hydroxide) in dmf, dmso ,dmac, etc with 4a mol sieves and
amine you get 70-90% just by stirring at room temp now that's simple.
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stoichiometric_steve
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so?
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jon
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well to say the least distlilling over na/k three times is tedious having to do everthing in an inert atmosphere is as well.
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stoichiometric_steve
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totally irrelevant. lets delete this shit
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Ebao-lu
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Anyway, rather interesting reaction. It is also mentioned that other Cp's can be used: alkyl, aryl, hydrogen (but cyclopentadiene is probably most
avaliable and stable). Hope in future, other metal complexes(not Sm) will be found to catalyse same reaction. As for mdma, another route of direct
amination of allylbenzenes is known: amine+allyl(propenyl)benzene+strong base.
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starman
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| Quote: | Originally posted by Ebao-lu
As for mdma, another route of direct amination of allylbenzenes is known: amine+allyl(propenyl)benzene+strong base. |
Really? I'm certainly not extensively read on this but the only reaction I've seen that treats allyl/propenyl forms identically is PdCl2 wacker
oxidation and amination proceeds via the ketone and reduction.
Do you have a reference to support this?
@Jon : I'm a little confused.First you talk about "little fuss" and "simple process" then you completely reverse yourself,bemoaning the tedium and
difficulty of it all,then throw in a speculative alternative reaction of your own design.Where were you intending to go with this?
[Edited on 16-12-2008 by starman]
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Ebao-lu
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| Quote: | Really? I'm certainly not extensively read on this but the only reaction I've seen that treats allyl/propenyl forms identically is PdCl2 wacker
oxidation and amination proceeds via the ketone and reduction.
Do you have a reference to support this? |
I dont know about mdma, the original procedure used unsubstituted allylbenzene(probably), benzylamine and butyllithium. I guess methylamine/safrole
could also work here.. The mechanism includes basic isomerisation to propenylbenzene, and addition of amide anion to double bond to form
alpha-position anion, that takes proton from amine, recycling amide anion. If it is required, i'll try to find the refference.
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Nicodem
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Hidroaminations of alkenes (formal addition of R<sub>2</sub>N-H over the double bond) are long known and can be performed trough various
mechanisms depending on what the substrate allows.
The transition metal catalyzed version, such as the example in the first post, is only one of the possibilities. This type of reaction often gives
either the product of oxidative hydroamination (enamine) trough the Wacker reaction mechanism or the hydroamination product by further reduction
(amines), but most commonly it gives a mixture of both in various proportions. See Synlett (2002) 1579-1594 for a review.
Then there is the nucleophilic addition of amines on the alkenes catalysed by bases strong enough to efficiently deprotonate the amine. It is most
efficient on alkenes where the intermediate carboanion is stabilized (such as styrenes where the benzylic anion which forms by the amide addition
further deprotonates another molecule of the amine, thus continuing the catalytic cycle), but essentially it can be used on other alkenes as well
(even such simple ones as ethene). See Adv. Synth. Catal., 344 (2002) 795-813 for a review; also J. Org. Chem., 37 (1971) 4243.
There is even the electrophilic addition version of hydroamination where an ammonium salt is used as the acid to protonate the alkene and
ammonia/amine as the nucleophile (essentially an NH3/NH4X buffer system). This type of reaction is poorly known in the academic literature (except for
many Chinese papers, there are only a couple in English). For obvious reasons it can only work on alkenes which get protonated very easily, such as
isobutenes (or tert-alcohols yielding the alkene in situ). The mechanism is kind of similar to the Ritter reaction, but the
nucleophile is the amine rather than a nitrile/urea/HSCN/etc. Since the acid used is terribly weak (by strength limited to the pKa of ammonium salts
which is about 9), the reaction requires some seriously extreme conditions (200-300°C). New versions are gas phase reactions between ammonia and the
alkene over acidic zeolites or silica (but still with extreme conditions). See US4937383; EP0200923; DE102005051044; EP1462165; WO2001085667; EP
814075; Journal of the Chemical Society, Faraday Transactions, 89 (1993) 3513-3514; Journal of Organic Chemistry, 53 (1988)
4594-4596..
A hydroamination of alkenes via a radical (photochemical) mechanism is also possible (photoamination). This is less known than the parent version
using phthalimide (photophtalimidization). Yet the reaction is reported to work with ammonia as well. See Journal of the Chinese Chemical Society,
50 (2003) 109-114, Bulletin of the Chemical Society of Japan, 71 (1998) 1655-1660, Tetrahedron Letters, 34 (1993) 5131-5134;
and references these papers.
| Quote: | Originally posted by Ebao-lu
I dont know about mdma, the original procedure used unsubstituted allylbenzene(probably), benzylamine and butyllithium. |
That would be Tetrahedron, 56 (2000) 5157-5162 or one of the older JOC papers where the use of BuLi as base in cyclohexane is described.
| Quote: | Originally posted by jon
first thing comes to mind is mdma but i can imagine you can have a lot of fun, and little fuss with this route any thoughts? |
This is not a forum for drug cooks so stop with your irrelevant comments. How do you imagine a half literate drug cook could ever succeed using this
reaction? Even such simple things like making the ketones from allylbenzenes trough double bond isomerization, epoxidation and epoxide rearrangement
or the Wacker oxidation represent a serious obstacle to them. If they would be able to use anything more involved then they would not be cooks any
more.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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starman
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@Nicodem : thanks for the brief tutorial and references.
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