Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Patent
1999-10-13
2000-11-28
McKane, Joseph K.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C07C 6900
Patent
active
061537861
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for preparing 2-alkynoic esters and to the use of certain catalysts for their preparation.
2-Alkynoic esters such as propiolic esters are important organic synthons and are used, inter alia, in the drugs sector. They can further be employed as fungicides or bactericides.
Numerous processes for preparing them are known.
JP-A 56 097 250 discloses the preparation of 2-alkynoic esters by reacting phenylacetylene with methanol and carbon monoxide in the presence of an oxidizing agent such as a combination of PdCl.sub.2, CuCl.sub.2 and alkali metal carboxylate in the presence of a catalyst such as PdCl.sub.2, Pd(NO.sub.3).sub.2 or PdSO.sub.4.
BE-A 871 888 discloses a process for preparing 2-alkynoic esters in which acetylenic compounds and dialkyl carbonates are reacted in the presence of a strong base. For example, dimethyl carbonate is reacted with 3-methyl-1-butyn-3-ol in the presence of sodium methanolate to give the methyl ester of 4-methyl-4-hydroxypentynoic acid.
Some of the above processes involve elaborate procedures, and they do not always give satisfactory results.
It is an object of the present invention to provide a process for preparing 2-alkynoic esters which leads directly to the required products under very mild conditions and with very high yields.
We have found that this object is achieved by a process for preparing 2-alkynoic esters of the general formula (I), C.sub.6-12 -aryl, C.sub.7-12 -aralkyl or C.sub.7-12 -alkylaryl radicals, and R.sup.2 can also be hydrogen, complex which has phosphine ligands and/or phosphite ligands as catalyst.
It has been found that 2-alkynoic esters can be prepared directly under very mild conditions and with very high yields from terminal alkynes and chloroformates using a palladium catalyst, preferably in the presence of a stoichiometric amount of base.
The catalysts employed for this purpose are Pt and Pd complexes, preferably Pd complexes, which have phosphine ligands and/or phosphite ligands. A large number of ligands are suitable as phosphine ligands or phosphite ligands. For example, the ligands may have the general formula PXYZ where X, Y and Z independently are alkyl, aryl, alkoxy or aryloxy radicals having up to 18 C atoms. Alkyl or aryl radicals are preferred, in particular aryl radicals. Corresponding ligands are described, for example, in DE-A-1 593 277. The Pd complexes are preferably Pd(0) and/or Pd(II) complexes having organic phosphine or phosphite ligands, in particular triarylphosphine ligands in which the aryl radicals can independently be substituted by C.sub.1-6 -alkyl radicals, preferably linear C.sub.1-4 -alkyl radicals, in particular linear C.sub.1-3 -alkyl radicals. The catalysts may moreover be formed in situ during the reaction. Examples of Pd(0) complexes are tetrakis(triphenyl-phosphine)palladium(0) (Pd(PPh.sub.3).sub.4) and tris(di-benzylideneacetone)dipalladium(0) in the presence of tri-o-tolylphosphine. The complexes can be composed, for example, of monodentate or bidentate ligands. Examples of suitable complex structures are the following: ##STR1## where the meanings are M Pd, Pt, preferably Pd the phosphorus atoms via O and/or C atoms, in particular aryl radicals or aryloxy radicals with 2 sites capable of bonding, particular aryl and/or aryloxy radicals
The charges are equalized, where appropriate by means of cations or anions not involved in coordinate bonds.
It is preferred for the monovalent radicals to be derived from benzene or phenol and for the divalent radicals to be derived from biphenyl, 1,1'-binaphthyl, biphenyloxy radicals and/or 1,1'-binaphthyloxy radicals. All the aromatic radicals can be substituted, for example by one or more C.sub.1-6 -alkyl radicals or corresponding alkoxy radicals. The biphenyl and binaphthyl radicals, and radicals derived therefrom, are bonded to the phosphorus atom by 2 positions in the molecule. The two positions may be bonded to the same phosphorus atom. It is also possible for them to be bonded to different phosphorus atoms and result in bridged structur
REFERENCES:
Yamamoto et al., J. Am. Chem. Soc., 103, 1981, 6133-6136.
Bottcher Arnd
de Backer Christel
Gleiter Rolf
Henkelmann Jochem
Preiss Thomas
BASF - Aktiengesellschaft
McKane Joseph K.
Murray Joseph
LandOfFree
Method for producing 2-alkynoic acid esters does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing 2-alkynoic acid esters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing 2-alkynoic acid esters will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1727245