Organic compounds -- part of the class 532-570 series – Organic compounds – Nitrogen attached directly or indirectly to the purine ring...
Patent
1996-02-22
1998-06-30
Raymond, Richard L.
Organic compounds -- part of the class 532-570 series
Organic compounds
Nitrogen attached directly or indirectly to the purine ring...
530335, 530336, 530337, 546217, 546245, 548492, 560 38, 560155, 564321, 564364, 564383, 564391, 564392, 564461, 564462, 556 13, C07C20962, C07K 106, C07K 112
Patent
active
057736170
DESCRIPTION:
BRIEF SUMMARY
The present application is a 371 of PCT/FR94/00397, filed Apr. 8, 1994.
The present invention relates to a reagent and to a process which are useful, when carrying out an organic synthesis, for cleaving an allylic group from a function protected by the latter.
It is common to protect a molecule by blocking the functions which, under the operating conditions envisaged, would be reactive or would be considered to be reactive, by groups described as being protecting groups.
These techniques are particularly useful during peptide syntheses or syntheses on (poly)nucleotides, and the functions most commonly protected are the acid, alcohol, amine or thiol functions.
These protection techniques are especially used for the synthesis of complex molecules such as peptides of at least 2 amino acids, usually of at least three, or when complex amino acids are used, that is to say those which have a function containing labile hydrogen (amine, alcohol including phenol, nitrogen-containing ring, thiol, etc.) in addition to an acid function and in addition to an amine function. They are also useful for nucleotides, nucleosides, polynucleotides and polynucleosides. A protecting group may also be useful for molecules having at least six, and advantageously twelve, carbon atoms, or for molecules which possess several functions, at least two and, advantageously, three functions.
Among the groups most commonly used, there may be mentioned the BOC or tert-butyloxycarbonyl group, Z or benzyloxy groups, or even the FMOC group. It should be pointed out that groups of allylic structure would have been considered as being potentially very valuable if suitable cleavage means were available.
To date, the only protecting groups of allylic type which are used are allyloxycarbonyl groups, the removal of which has been dealt with in previous applications (in particular the application filed in France under No. 92/04621 and the corresponding European application) by the Applicant and which should not be confused with the allyl derivatives according to the present application; these allyloxycarbonyl derivatives have a carbonyl function derived from an acid function, which makes the cleavage easier.
The deprotection usually used is lysis in an acidic medium, generally in an anhydrous hydrohalic medium (that is to say one with a water content generally of less than 1%, advantageously of less than 10.sup.-3 and preferably of less than 10.sup.-4).
However, this technique has a number of drawbacks. The cleavage reaction is sometimes slow or requires large excesses of reagent. Alkoxy groups have a tendency to be converted into carbocation with a change towards double bonds when this is possible, or towards alkylation reactions on the ring, which is particularly inconvenient in the case of syntheses of peptides whose sequence contains nucleophilic residues such as aromatic rings (tryptophan, tyrosine, etc.) or sulphur-containing residues (methionine).
This technique is not applicable in the case of allylic groups, which is why these groups, which otherwise would have numerous advantages, are not used.
Accordingly, one of the aims of the present invention is to provide a process and a reagent which allow the cleavage of an allylic protecting group from the function which it protects.
Another aim of the present invention is to provide a process and a reagent which avoid the alkylation reactions of aromatic rings.
Another aim of the present invention is to provide a process and a reagent which avoid the alkylations of function(s) belonging to the same molecule and described as being nucleophilic.
These aims and others which will emerge in the following text, are achieved using a reagent which is useful for cleaving allylic, so-called protective, groups. From the functions which it is supposed to protect.
The reagent according to the present invention contains: Periodic Table of the Elements, the said element from column VIII of the Periodic Table being coordinated with at least one coordination agent which is soluble in the said solvent system; system
REFERENCES:
Noyori et al., Chemical Abstracts, vol. 109, abstract 129602w, 1988.
Kamber et al., Canadian Journal of Chemistry, vol. 63, No. 4, pp. 823-827, 1985.
Bernard Jean-Marie
Blart Errol
Genet Jean-Pierre
Lemaire-Audoire Sandrine
Savignac Monique
Raymond Richard L.
Rhone-Poulenc Chimie
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