Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1990-12-14
1992-12-08
Griffin, Ronald W.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
106162, 536 11, 568338, 568383, 568426, 568449, 568950, C08B 3700, C07H 100, C07H 300
Patent
active
051699435
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention concerns a novel chiral reaction medium for organic reactions.
There is widespread need in industry to optimize organic reactions and research is constantly undertaken to that end. Much work has been done in particular on increasing the reaction rates. Such increase in reaction rate most of the time has been possible only by resorting to catalyst(s) and/or to high pressures, entailing steps which are costly and/or difficult to carry out. Again frequently the use of organic solvents has been advocated, where called for in combination with other steps such as those cited above, but besides the generally high, even prohibitive cost of such solvents, their use raises problems because of their toxicity.
Again there is widespread industrial need to control the selectivity of organic reactions, in particular the regio-selectivity, the stereo-selectivity, the enantio-selectivity and the chemo-selectivity. Various solutions already have been suggested in this respect in relation to the particular problem to be solved, and among these is the use of chiral solvents, however the latter's cost is so high that processes involving reactions carried out in such solvents are economically of little interest.
The present invention provides a reaction medium which makes it possible to substantially increase the rates of organic reactions and where called for to modify their selectivities while palliating the aforementioned difficulties.
Accordingly the present invention provides an organic reaction medium consisting of a concentrated aqueous solution of at least one carbohydrate selected among the mono-, di- and tri-saccharides and their alkylglycosides of which the alkyl group comprises from 1 to 4 carbon atoms.
In illustrative but non restrictive manner, the carbohydrates applicable within the present invention are glucose, fructose, saccharose, ribose, galactose, mannose, .alpha.-methyl-glucoside.
The expression "concentrated solution" means a solution with a concentration at least about 0.2 M; this value however is not critical and the lower concentration limit of said carbohydrate is easily determined by the expert for the particular reaction being considered.
The present invention shall now be discussed comprehensively with particular reference to the Diels-Alder reactions, but it must be borne in mind that the illustration provided by this sort of reaction is merely illustrative both of the unexpected character of the invention and some advantages it may provide, no restriction of its scope being in any way implied.
It is known that the Diels-Alder reactions are considerably accelerated in water as compared to organic solvents (see RIDEOUT, D. C., BRESLOW, R. J. AM. CHEM. SOC. 1980, 102, 7816; GRIECO, P. A.; YOSHIDA, K., GARNER, P. J. ORG. CHEM. 1983, 48, 3139 and LUBINEAU, A., QUENEAU, Y., J. ORG. CHEM. 1987, 52, 1001).
It is further known that cyclodextrin .beta. accelerates Diels-Alder reactions in an aqueous medium by forming hydrophobic diene and dienophil accumulation inside its hydrophobic cage (Rideout, D. C., Breslow, R. J. AM. CHEM. SOC. 1980, 102, 7816, LOC. ClT., and STERNBACH, D. D., ROSSANA, D. M. J. AM. CHEM. SOC. 1982, 104, 5853).
The cyclodextrins are carbohydrates but contrary to the case of the mono-, di- and tri-saccharides used in the present invention, they consist of 6, 7 or 8 glucose units forming a ring which comprises at its center a hydrophobic cage.
Aqueous solutions of mono-, di- and tri-saccharides not being known to form such cages, it might be expected that acceleration in such medium would be much less than in a reaction medium consisting of a saturated solution of said cyclodextrin.
Surprisingly the applicant found not only that aqueous solutions of carbohydrates selected among the mono-, di- and tri-saccharides and their alkylglycosides wherein the alkyl group comprises from 1 to 4 C atoms constitute a reaction medium allowing an increase in the rate of organic reactions, but also that the acceleration so obtained may even be significantly higher tha
REFERENCES:
patent: 4144261 (1979-03-01), Chan
Manuel of Medical Therapeutics, 23rd Edition, Freitag et al. editors, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, Little Brown and Company Boston, Mass. (1980), p. 401.
Bienayme Hugues
Lubineau Andre
Queneau Yves
Beghin-Say S.A.
Griffin Ronald W.
LandOfFree
Chiral reaction medium for organic reactions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Chiral reaction medium for organic reactions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chiral reaction medium for organic reactions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-961796