gorecore - 19-12-2007 at 12:07
hi everyone...i'm since wow...a lot of time...because i wasn't able to do it...(broke computer)...well i'm back...and i need help for a reaction...
i know the normal halohydrin reaction, but in this case i need the other product (in the square) in a higher yield.....someone please can help me to
find a way to improve the characteristics of my reaction, or helping me with some article in which i can take some ideas...or a book...
thanks so much
Nicodem - 19-12-2007 at 13:55
You will always obtain the "preferred" product as the major product (assuming the gamma position is a methylene). If you are ready to do a column
chromatography for a reaction yielding something like 10-20% selectivity of the "other" regioisomer and you don't mind the X=Cl than do a
chlorohydrine. Their formation is the least regioselective and will give you the lowest regioselectivity (which is what you want as I assume).
But do you mind explaining the next step (the substitution with R-NH2)? How are you going to do that when the nucleophilic substitution of both
halohydrines always yield the same product composition? In your case this would be the other regioisomer with the amino group at the terminal
position: -(CH2)n-CH(OH)-CH2-NH-R. So, if the reason you want the "other" halohydrine is because you are not familiar with the mechanism of the
nucleophilic substitutions at halohydrines, then rather reconsider and find another, possibly working synthetic route.
gorecore - 19-12-2007 at 14:35
well thanks...for the advice...but i'm very aware of the mechanism, also the products that i can have in my reaction, this is more like a
dream...haha...because i already have another method of synthesis for the compound with the NHR, and the yields are good, but i was looking something
a little bit more quick and hopefully with better yields than my first method, recently i was reading some books and articles of asymmetric halohydrin
synth...but they obtain products as these with low yields, also i was looking for some aminohydroxylation reactions of olefins....and those were
looking more interesting...
thanks for your help...