Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1993-06-03
1995-11-28
Ivy, C. Warren
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C07D30702
Patent
active
054709911
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/CH92/00199 filed Oct. 2, 1992.
The invention is concerned with a process for the manufacture of substituted furans; thereby 4-hydroxy-2-yn-1-ones or acetals or ketals thereof are cyclized with nucleophilic S-compounds to 3-S-furans, whereby this 3-S atom can be optionally substituted, and the acetylene derivatives, the 4-hydroxy-2-yn-1-ones, can be optionally 1- and/or 4-alkyl or alkenyl substituted.
More particularly, the invention is concerned with a process for the manufacture of substituted furan derivatives of the formula ##STR1## wherein R.sup.1 and R.sup.2 signify hydrogen, C.sub.1-6 -alkyl, such as CH.sub.3, C.sub.2 H.sub.5 or C.sub.2-6 -alkenyl, such as propenyl, etc. and C represents a sulphur-containing radical --B or --S--R, defined below. ##STR2## or an acetal or ketal thereof using a reagent III which contains at least one nucleophilic sulphur atom metal cation, an alkaline earth metal cation, NC(=S)NH.sup.-, R.sup.5 --S(=O)O.sup.-, R.sup.5 --S--S.sup.-, and substituted by halogen (F, Cl, Br, I), OH, SH, C=O or a C.sub.1-6 -carboxylic acid residue or a C.sub.1-6 -alkylcarboxylic acid derivative, e.g. --CH.sub.2 (CH.sub.2).sub.2 COOC.sub.2 H.sub.5, --CH.sub.2 CH(CH.sub.3)CH.sub.2 COCH.sub.3, --CH.sub.2 CH(CH.sub.3)SH, substituted (optionally also heterocyclically) C.sub.1-6 -acyl, e.g. 2-tetrahydrofuranylmethylcarbonyl, especially residues of 5-ring compounds, such as furyl or thiophenyl, ##STR3## by a secondary reaction into a subsequent product of the formula ##STR4## wherein R=R.sup.4 ; or SR.sup.5, e.g. S--C.sub.1-6 -alkyl, such as S--CH.sub.3, S-sec.butyl, etc., S--C.sub.1-6 -alkyl functionalized with halogen, hydroxy, SH, carbonyl, carboxyl, S-alkyl, such as thiophenyl, S-heteroaryl, such as thio-furfuryl; 3-S-thio-furyl; 3-S-thiophenyl, optionally substituted by R.sup.1 and R.sup.2 and all hydrocarbon residues can be straight-chain or branched.
The process can be represented schematically as follows: ##STR5##
The starting materials II and III are conveniently brought together in the ratio of about 2:1 to about 1:5, preferably about 1:1, with the addition of a mineral acid, such as nitric acid, phosphoric acid or, preferably, sulphuric acid, or an organic acid, e.g. acetic acid, citric acid, etc., and an organic solvent, such as an aliphatic or aromatic, optionally halogenated hydrocarbon, an ether, an alcohol, etc., such as pentane, methylene chloride, toluene, diethyl ether, tetrahydrofuran, MTBE, ethanol, etc., and stirred at temperatures of about 0.degree. to about 100.degree. C., preferably about 20.degree.-50.degree. C.
Preferably, II is added dropwise to III and processed at pH values below about 4. In certain cases it has been observed that prior base treatment of the mixture of starting materials II+III expedites the addition of B in the .beta.-position of II. As bases there can preferably be used in this case tertiary amines, such as e.g. N(C.sub.2 H.sub.5).sub.3, diazabicyclooctane, p-diaminopyridine, etc. The suitable temperatures are about 20.degree. to about 50.degree. C. This procedure is indicated especially when AB=R.sup.4 SH, R.sup.5 --S--S--H, etc.
The reaction of II with III can be carried out in a one-phase or two-phase (polar/apolar) system. The latter variant is preferred. In the case of the first variant, the reaction is preferably carried out in polar solvents, such as alcohols, e.g. ethanol, etc., acetone, acetonitrile, water, etc. or mixtures of such solvents.
The acetalization or ketalization of II is effected in a manner known per se and the meanings of R.sup.3 in formula II(b) are: ##STR6## R.sup.3 =C.sub.1-4 -alkyl R.sup.3 +R.sup.3 +C of IIb=5- or 6-membered ring.
The radical B of compound I' can be subjected to subsequent reactions, whereby the compound I" results. The nature of the subsequent reaction depends especially on the nature of B.
For the secondary reactions I'.fwdarw.I" the following generally applies: reactions .alpha.) to .delta.) hereinafter are standard reactions which are well-known to a person skilled in th
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Givaudan-Roure Corporation
Gould George M.
Ivy C. Warren
Johnston George W.
Owens A. A.
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