- Email: [email protected]
Incorporation of CO2 into organic perfluoroalkyl derivatives by electrochemical methods
T. Inui, M. Anpo, K. Izui, S. Yanagida, T. Yamaguchi (Editors) Advances in Chemical Conversions for Mitigating Carbon Dioxide Studies in Surface Science and Catalysis, Vol. 114 9 1998 Elsevier Science B.V. All rights reserved.
I n c o r p o r a t i o n of CO2 i n t o o r g a n i c p e r f l u o r o a l k y l electrochemical methods
213
derivatives
by
E. Chiozza a, M. Desigaud a, J. Greiner b, E. Dufiach a aLaboratoire de Chimie Mo!~culaire, Associ~ au CNRS, URA 426, Universit~ de Nice-Sophia Antipolis, 06108 Nice Cedex 2, France bLaboratoire de Chimie Bioorganique, Associ6 au CNRS, ESA 6001, Universit6 de Nice-Sophia Antipolis, 06108 Nice Cedex 2, France
The CO2 fixation into (perfluoroalkyl)iodoalkanes, (perfluoroalkyl)iodoalkenes and (perfluoroalkyl)alkenes, catalyzed by e!ectrogenerated nickel complexes, afforded perfluoroa!kyl carboxylic acid derivatives. The electrocarboxylation of perfluoroalkyl olefins proceeded with double bond migTation and loss of an ally!ic fluorine atom. 1. I N T R O D U C T I O N
We have been interested in the carbon dioxide fixation into organic substrates for the s3~nthesis of speciality products of the carboxylic acid family. We focussed our attention on the formation of new carbon-carbon bonds between CO2 and perfluoroa!ky! derivatives, particularly perfluoroalkyl olefins. The perfluorinated chain being highly hydrophobic, the expected perfluoroa!kyl carboxy!ic acids are precursors of amphiphi!ic molecules, of interesting applicability in the field of surfactants and medicinal chemistry [1]. The fixation of carbon dioxide into functionalized organic substrates to selectively afford carboxylic acids in catalytic reactions is still a challenge in carbon dioxide chemistry [2]. In the field of o!efin carboxy!ation, stoichiometric reactions have been described to occur between non-activated alkenes, CO2 and an electron-rich transition-metal complexes, such as Ni(0) [3], Ti(!!) [4] or Fe(0) [5]. A Pdcatalyzed CO2 fixation occurs into methylenecyclopropane derivatives affording !actones [6]. The reaction of carbon dioxide with ethylene is difficult and its carboxylation to propionic acid, catalyzed by Rh derivatives [7], needs drastic experimental conditions. The direct carboxylation ofperfluoroalkyl iodides has been reported to afford RFCO2H in the presence of a Zn-Cu couple [8] or that of zinc and ultrasounds [9]. To our knowledge, no reports on the carbon dioxide fixation into perfluoroalkyl olefins have been yet described.
214 Our synthetic method for CO2 fixation was based on the use of transitionmetal catalysis combined with electrochemical techniques [10]. Within this methodology, the electrochemical C02 fixation into some a!kenes has been reported to afford carboxylic acids in a reductive hydrocarboxylation-type reaction c a t a l y z e d by nickel complexes, u n d e r mild conditions [1!]. The electrocarboxylation of organic halides to the corresponding carboxylic acids has also been reported [12], )4e!ds and efficiency of the reaction being strongly dependent on the reaction conditions. 2. ELECTROCARBOXYLATIONS The catalytic incorporation of carbon dioxide into alkene derivatives remains an interesting goal in CO2 chemistry, and in the present study, we wish to examine the influence of the perfluoroalkyl (RF) chain (RF CnF2n+l) on the electrocarboxylation of a double bond, as well as on that of other perfiuoroalkyl iodo derivatives. Substrates 1-4, containing RF substituents (Cf. eqs. 1-3) have been prepared according to literature procedures [13]. Their electrochemical behaviour and in particular, the CO2 fixation under mild conditions have been examined in the presence of several nickel(II) complexes used as catalyst precursors. Ni(!I) derivatives associated to polydentate nitrogen ligands have been reported as efficient catalysts in the electrochemical carboxylation of alk)~es [14] and di:~es [15]. Thus, Ni(II) complexes such as Ni(bipy)32+, 2BF4- (bipy = 2,2'-bipyridine) [16], Ni(cyclam)Br2 (cyclam = !,4,8,11-tetraazacyclotetradecane) [17], or NiBr2(dme) with N,N,N',N",N"-pentamethyldiethylene triamine (PMDTA) (dme = dimethoxyethane) [18] have been prepared and used in catalytic amounts in e!ectrocarboxylation. The general electrochemical procedure for the carbon dioxide incorporation was based on the use of one-compartment cells fitted with consumable anodes of magnesium or zinc [12]. E!ectrocarboxylations were carried out in DMF at constant current density, using tetrabutylammonium tetrafluoroborate (10 -2 M) as supporting electrolyte. The catalyst was introduced in a 10% molar ratio with respect to the substrate and carbon dioxide was bubbled through the solution at atmospheric pressure. Electrolyses were generally run at room temperature and reactions were stopped when starting material was consumed or when the farada'~c yield attained 30%. =
2.1. Electrocarboxylation reactions of (perfluoroalkyl)iodoalkanes and (perfluoroalkyl)iodoalkenes The electrocarboxylation of 1 took place under mild conditions (C02 pressure of I atm, T = 20~ in the presence of Ni(bipy)32+, 2BF4- as the catalyst precursor and a Mg/stainless steel couple of electrodes, to afford the corresponding perfluoroalkyl carboxylic acid 5 in 30% yield, together with the olefin 3 [20%, E / Z 90:10)] (eq. 1).
215 I CO2H ,~H I 1) Ni-bipy,cJ C8F17~ CsFI7CH 2 CHC4H 9 + --"C C8FITCH 2 CH C4H 9 + CO 2 DMF,Mg anode H ~C i~C4H 9 1 2) hydrolysis • 3 (eq. 1) The electrocarboxylation of the same substrate in the absence of the nickel catalyst did not afford any carboxylic acids derived from 1. The electrocarboxylation of(perfluoroalkyl)iodoalkene 2 (E/Z 90:10) under 1 atm of CO2 (Mg/Ni electrodes, Ni-bipy catalytic system) allowed the formation of unsaturated carboxylic acid 6 in 10% yield (E/Z 85:15) (eq. 2). Olefin 3, issued from the reduction of the halide function by protodehalogenation, was obtained in 30% together with 25% of unreacted starting material.
C8F17 ..C-'-" C~r + CO I) Ni-bipy,e- ~C8Fi7 "H/C=C~'r CO2H c+8 F 1H7 ~ C : C H C4H9 2 DMF,Mg anode ~ C4H 9 2 2) hydrolysis 6 3
~,jH I~C4H9 (eq. 2)
2.2. Electrocarboxylation of (perfluoroalkyl)alkenes The Ni-catalyzed electrocarboxy!ation of differently activated olefins has been reported to afford selective CO2 incorporation via hydrocarboxylation [11]. However, no CO2 incorporation occurred with non-activated alkenes such as 1- or 4-octene. Carboxylation of olefins 3 and 4 should give some indication on the influence of the RF substituent on the double bond. The electrolyses of olefins 3 and 4 (eq. 3) in the presence of CO2 led to the synthesis of carboxylic acids, and have been carried out using bipy, cyclam or PMDTA as the ligands on nickel (Table 1). Table 1 Influence of the ligands of the Ni(II) catalyst on the electrocarboxylation of substrates 3 and 4 (room temperature; CO2 1 atm; electrodes: M~stainless steel)
Starting compounds CsF17-CH=CH-C4H9 3 C6F13-CH=CH-CsH17 4
Nature of the !igand bipy cyclam bipy cyclam PMDTA
Carboxylic acids 20% 65% 30% 92% 64%
216 The results indicate that the Ni-cyclam catalytic system offers the best yields of carboxylation, and up to 92% of CO2 incorporation into 4 could be achieved. However, the carboxylic acids were not issued from the expected hydrocarboxylation of the double bond. We could respectively identify the two (E) and (Z) isomers of the ~,y-unsaturated acids 7 and 8 (isolated as their methyl esters, eq. 3), containing a vinyl fluorine substituent. The relative yields of products 7 and 8 were 45% ( E / Z = 30/70) and 56% ( E / Z = 37/63), respectively. R~\C= / H C\CH_R u F/ i
Rp-CF2 H;C:C 3
~H +
RH
COeMe
]) e-, Ni(II)L CO 2
Z
+
2) K2CO3, MeI
or 4
Rt=~ 3, 7 RF= C7F15, RH= C4H9 4,8 RF=CsFll, RH=C8H17
7 or 8
CO2Me / CH- RH
F/C=C\H
7 or 8 E (eq. 3)
Thus, both perfluoroalkyl olefins 3 and 4 incorporated CO2 on one of the initial vinyl carbons, regioselectively on the site of the hydrocarbon chain. The carboxylation process involves a shift of the double bond, with the loss of one fluorine atom from the allylic positi'on. The influence of the temperature on the electrocarboxylation was examined, and showed that the Ni-bipy catalytic system was more efficient at 60~ than at 20~ Thus, 58% and 86% yields of carboxylic acids were obtained at 60~ from 3 and 4, respectively. 3. M E C H A N I S T I C
STUDIES
In order to explain the results involving RF-olefin electrocarboxylation reaction with allylic double bond migration, cyclic voltammetric studies were carried out and electrolyses were conducted under stoichiometric conditions in the particular case of the Ni-bipy catalytic system with perfluoroalkyl olefin 3. Several experiments with electrogenerated Ni(0)(bipy)2 complex at -1.0 V vs Ag/AgC1 indicated that no activation of the allylic C-F bond occurred at this potential. Controlled potential experiments at-1.7 V under CO2 led to the formation of the corresponding RF-carboxylic acid, 7. According to these results, the catalytic cycle shown in Figure i is proposed. Reduced nickel species, such as [Ni(bipy)2]', could be responsible for the catalytic activity in the carboxylation process.
217
[Ni(bipy!,,3,1 F,,x '
~ + 2e" (-1,2 V)
R/ ~ ~ RH Mg ~ F'~ Anode:
RFCF2~""--~RH
L2Ni(0)
e" (-1,7v)
FNiO L
CO2
Figure 1. Proposed m e c h a n i s m for the electrocatalytic carboxylation of (periluoroalkyl)alkenes 4. CONCLUSIONS The electrochemical incorporation of CO2 into perfluoroalkyl derivatives has b e e n e x p l o r e d in t h e case of ( p e r f l u o r o a l k y l ) a l k y l iodides and (perfluoroalkyl)alkenes, with an electrochemical system based on the use of consumable anodes combined with organometallic catalysis by nickel complexes. Iodide derivatives have been functionalized to the corresponding carboxylic acids by reductive carboxylation. Interesting and new results have been obtained from the fixation of CO2 into perfluoroalkyl olefins. Good yields of carboxylic acids could be reached by a carefull control of the reaction conditions and of the nature of the catalytic system. The main carboxylic acids are derived from the incorporation of carbon dioxide with a double bond migration and loss of one fluorine atom from the CF2 in ~ position of the double bond. The formation of carboxylic acids from perfluoroalkyl olefins reveals an important influence of the perfluoroalkyl chain on the carboxylation process. Thus, no carboxylation occurred in the case of related non-activated alkyl olefins under the same reaction conditions. These results constitute the first example in which an allylic reactivity involving a double bond migration is observed in electrochemical carboxylations.
218 REFERENCES
1.
a) E. Kissa, Fluorinated Surfactants. Synthesis, Properties, Applications, Surfactant Science Series, Vol. 50, M. Dekker, New York, 1994. b) J. G. Riess, J. Greiner and P. Vierling, In Organofluorine Compounds in Medicinal Chemistry and Biomedical Applications, R. Filler, Y. Kobayashi and L. 1Y[ Yagupolskii (eds), Elsevier, Amsterdam, London, New York, Tokyo, pp 339380, 1993. 2. M. Aresta and G. Forti (eds.), Carbon Dioxide as a Source of Carbon, Nato ASI Series, Series C, Vol. 206, Dordrecht, 1987. 3. a) H. Hoberg, Y. Peres, C. Krtiger and Y. H. Tsay, Angew. Chem., Int. Ed. Eng., 26 (1987) 771. b) D. Walther, E. Dinjus, J. Sieler and L..4~dersen, J. Organomet. Chem., 276 (1984) 99. 4. S.A. Cohen and J. E. Bercaw, Organometallics, 4 (1985) 1006. 5. H. Hoberg, K. Jenni, K. Angermund and C. Kruger, Angew. Chem., Int. Ed. Eng., 99 (1987) 141. 6. P. Binger and H. J. Weintz, Chem. Ber., 117 (1984) 654. 7. A. L. Lapidus, S. D. Pirozhkov and A. A. Koryakin, Bull. Acad. Sci. USSR., Div. Chem. Sci. (Engl. Trans), (1978) 2513. 8. H. Blancou, P. Moreau and A. Commes~as, J. Chem. Soc., Chem. Commun., (1976) 885. 9. N. Ishikawa, M. Takahashi, T. Sato and T. Kitazume, J. Fluorine Chem., 22 (1983) 585. 10. H. Lund and M. Baizer in Organic Electrochemistry, M. Dekker, New York, 3 rd Ed., 1990. 11. S. Derien, J. C. Clinet, E. Dufiach and J. P~richon, Tetrahedron, 48 (1992) 5235. 12. a) J. Chaussard, J. C. Folest, J. Y. Ndd~lec, J. P~richon, S. Sibille and M. Troupel, Synthesis, (1990) 369. b) G. Silvestri, S. Gambino, G. Filardo and A. Gulota, Angew. Chem., Int. Ed. Engl., 23 (1984) 979. 13. a) N. O. Brace, J. Org. Chem., 27 (1962) 3033. b) N. O. Brace, J. Fluorine. Chem., 20 (1982) 313. c) A. Manfredi, S. Abouhilale, J. Greiner and J. G. Riess, Bull. Soc. Chim. Fr., (1990) 872. d) D. J. Burton and L. J. Kehoe, Tetrahedron Lett., (1966) 5163. 14. S. Derien, E. Dufiach and J. P~richon, J. Am. Chem. Soc., 113 (1981) 8447. 15. S. Derien, J. C. Clinet, E. Dufiach and J. Pdrichon, J. Org. Chem., 58 (1993) 2578. 16. E. Dufiach and J. P6richon, J. Organomet. Chem., 352 (1988) 239. 17. B. Bosnich, C. I~ Poon and M. L. Tobes, Inorg. Chem., 4 (1965) 1102. 18. E. Dufiach and J. Pdrichon, Synlett, (1990) 143.
I n c o r p o r a t i o n of CO2 i n t o o r g a n i c p e r f l u o r o a l k y l electrochemical methods
213
derivatives
by
E. Chiozza a, M. Desigaud a, J. Greiner b, E. Dufiach a aLaboratoire de Chimie Mo!~culaire, Associ~ au CNRS, URA 426, Universit~ de Nice-Sophia Antipolis, 06108 Nice Cedex 2, France bLaboratoire de Chimie Bioorganique, Associ6 au CNRS, ESA 6001, Universit6 de Nice-Sophia Antipolis, 06108 Nice Cedex 2, France
The CO2 fixation into (perfluoroalkyl)iodoalkanes, (perfluoroalkyl)iodoalkenes and (perfluoroalkyl)alkenes, catalyzed by e!ectrogenerated nickel complexes, afforded perfluoroa!kyl carboxylic acid derivatives. The electrocarboxylation of perfluoroalkyl olefins proceeded with double bond migTation and loss of an ally!ic fluorine atom. 1. I N T R O D U C T I O N
We have been interested in the carbon dioxide fixation into organic substrates for the s3~nthesis of speciality products of the carboxylic acid family. We focussed our attention on the formation of new carbon-carbon bonds between CO2 and perfluoroa!ky! derivatives, particularly perfluoroalkyl olefins. The perfluorinated chain being highly hydrophobic, the expected perfluoroa!kyl carboxy!ic acids are precursors of amphiphi!ic molecules, of interesting applicability in the field of surfactants and medicinal chemistry [1]. The fixation of carbon dioxide into functionalized organic substrates to selectively afford carboxylic acids in catalytic reactions is still a challenge in carbon dioxide chemistry [2]. In the field of o!efin carboxy!ation, stoichiometric reactions have been described to occur between non-activated alkenes, CO2 and an electron-rich transition-metal complexes, such as Ni(0) [3], Ti(!!) [4] or Fe(0) [5]. A Pdcatalyzed CO2 fixation occurs into methylenecyclopropane derivatives affording !actones [6]. The reaction of carbon dioxide with ethylene is difficult and its carboxylation to propionic acid, catalyzed by Rh derivatives [7], needs drastic experimental conditions. The direct carboxylation ofperfluoroalkyl iodides has been reported to afford RFCO2H in the presence of a Zn-Cu couple [8] or that of zinc and ultrasounds [9]. To our knowledge, no reports on the carbon dioxide fixation into perfluoroalkyl olefins have been yet described.
214 Our synthetic method for CO2 fixation was based on the use of transitionmetal catalysis combined with electrochemical techniques [10]. Within this methodology, the electrochemical C02 fixation into some a!kenes has been reported to afford carboxylic acids in a reductive hydrocarboxylation-type reaction c a t a l y z e d by nickel complexes, u n d e r mild conditions [1!]. The electrocarboxylation of organic halides to the corresponding carboxylic acids has also been reported [12], )4e!ds and efficiency of the reaction being strongly dependent on the reaction conditions. 2. ELECTROCARBOXYLATIONS The catalytic incorporation of carbon dioxide into alkene derivatives remains an interesting goal in CO2 chemistry, and in the present study, we wish to examine the influence of the perfluoroalkyl (RF) chain (RF CnF2n+l) on the electrocarboxylation of a double bond, as well as on that of other perfiuoroalkyl iodo derivatives. Substrates 1-4, containing RF substituents (Cf. eqs. 1-3) have been prepared according to literature procedures [13]. Their electrochemical behaviour and in particular, the CO2 fixation under mild conditions have been examined in the presence of several nickel(II) complexes used as catalyst precursors. Ni(!I) derivatives associated to polydentate nitrogen ligands have been reported as efficient catalysts in the electrochemical carboxylation of alk)~es [14] and di:~es [15]. Thus, Ni(II) complexes such as Ni(bipy)32+, 2BF4- (bipy = 2,2'-bipyridine) [16], Ni(cyclam)Br2 (cyclam = !,4,8,11-tetraazacyclotetradecane) [17], or NiBr2(dme) with N,N,N',N",N"-pentamethyldiethylene triamine (PMDTA) (dme = dimethoxyethane) [18] have been prepared and used in catalytic amounts in e!ectrocarboxylation. The general electrochemical procedure for the carbon dioxide incorporation was based on the use of one-compartment cells fitted with consumable anodes of magnesium or zinc [12]. E!ectrocarboxylations were carried out in DMF at constant current density, using tetrabutylammonium tetrafluoroborate (10 -2 M) as supporting electrolyte. The catalyst was introduced in a 10% molar ratio with respect to the substrate and carbon dioxide was bubbled through the solution at atmospheric pressure. Electrolyses were generally run at room temperature and reactions were stopped when starting material was consumed or when the farada'~c yield attained 30%. =
2.1. Electrocarboxylation reactions of (perfluoroalkyl)iodoalkanes and (perfluoroalkyl)iodoalkenes The electrocarboxylation of 1 took place under mild conditions (C02 pressure of I atm, T = 20~ in the presence of Ni(bipy)32+, 2BF4- as the catalyst precursor and a Mg/stainless steel couple of electrodes, to afford the corresponding perfluoroalkyl carboxylic acid 5 in 30% yield, together with the olefin 3 [20%, E / Z 90:10)] (eq. 1).
215 I CO2H ,~H I 1) Ni-bipy,cJ C8F17~ CsFI7CH 2 CHC4H 9 + --"C C8FITCH 2 CH C4H 9 + CO 2 DMF,Mg anode H ~C i~C4H 9 1 2) hydrolysis • 3 (eq. 1) The electrocarboxylation of the same substrate in the absence of the nickel catalyst did not afford any carboxylic acids derived from 1. The electrocarboxylation of(perfluoroalkyl)iodoalkene 2 (E/Z 90:10) under 1 atm of CO2 (Mg/Ni electrodes, Ni-bipy catalytic system) allowed the formation of unsaturated carboxylic acid 6 in 10% yield (E/Z 85:15) (eq. 2). Olefin 3, issued from the reduction of the halide function by protodehalogenation, was obtained in 30% together with 25% of unreacted starting material.
C8F17 ..C-'-" C~r + CO I) Ni-bipy,e- ~C8Fi7 "H/C=C~'r CO2H c+8 F 1H7 ~ C : C H C4H9 2 DMF,Mg anode ~ C4H 9 2 2) hydrolysis 6 3
~,jH I~C4H9 (eq. 2)
2.2. Electrocarboxylation of (perfluoroalkyl)alkenes The Ni-catalyzed electrocarboxy!ation of differently activated olefins has been reported to afford selective CO2 incorporation via hydrocarboxylation [11]. However, no CO2 incorporation occurred with non-activated alkenes such as 1- or 4-octene. Carboxylation of olefins 3 and 4 should give some indication on the influence of the RF substituent on the double bond. The electrolyses of olefins 3 and 4 (eq. 3) in the presence of CO2 led to the synthesis of carboxylic acids, and have been carried out using bipy, cyclam or PMDTA as the ligands on nickel (Table 1). Table 1 Influence of the ligands of the Ni(II) catalyst on the electrocarboxylation of substrates 3 and 4 (room temperature; CO2 1 atm; electrodes: M~stainless steel)
Starting compounds CsF17-CH=CH-C4H9 3 C6F13-CH=CH-CsH17 4
Nature of the !igand bipy cyclam bipy cyclam PMDTA
Carboxylic acids 20% 65% 30% 92% 64%
216 The results indicate that the Ni-cyclam catalytic system offers the best yields of carboxylation, and up to 92% of CO2 incorporation into 4 could be achieved. However, the carboxylic acids were not issued from the expected hydrocarboxylation of the double bond. We could respectively identify the two (E) and (Z) isomers of the ~,y-unsaturated acids 7 and 8 (isolated as their methyl esters, eq. 3), containing a vinyl fluorine substituent. The relative yields of products 7 and 8 were 45% ( E / Z = 30/70) and 56% ( E / Z = 37/63), respectively. R~\C= / H C\CH_R u F/ i
Rp-CF2 H;C:C 3
~H +
RH
COeMe
]) e-, Ni(II)L CO 2
Z
+
2) K2CO3, MeI
or 4
Rt=~ 3, 7 RF= C7F15, RH= C4H9 4,8 RF=CsFll, RH=C8H17
7 or 8
CO2Me / CH- RH
F/C=C\H
7 or 8 E (eq. 3)
Thus, both perfluoroalkyl olefins 3 and 4 incorporated CO2 on one of the initial vinyl carbons, regioselectively on the site of the hydrocarbon chain. The carboxylation process involves a shift of the double bond, with the loss of one fluorine atom from the allylic positi'on. The influence of the temperature on the electrocarboxylation was examined, and showed that the Ni-bipy catalytic system was more efficient at 60~ than at 20~ Thus, 58% and 86% yields of carboxylic acids were obtained at 60~ from 3 and 4, respectively. 3. M E C H A N I S T I C
STUDIES
In order to explain the results involving RF-olefin electrocarboxylation reaction with allylic double bond migration, cyclic voltammetric studies were carried out and electrolyses were conducted under stoichiometric conditions in the particular case of the Ni-bipy catalytic system with perfluoroalkyl olefin 3. Several experiments with electrogenerated Ni(0)(bipy)2 complex at -1.0 V vs Ag/AgC1 indicated that no activation of the allylic C-F bond occurred at this potential. Controlled potential experiments at-1.7 V under CO2 led to the formation of the corresponding RF-carboxylic acid, 7. According to these results, the catalytic cycle shown in Figure i is proposed. Reduced nickel species, such as [Ni(bipy)2]', could be responsible for the catalytic activity in the carboxylation process.
217
[Ni(bipy!,,3,1 F,,x '
~ + 2e" (-1,2 V)
R/ ~ ~ RH Mg ~ F'~ Anode:
RFCF2~""--~RH
L2Ni(0)
e" (-1,7v)
FNiO L
CO2
Figure 1. Proposed m e c h a n i s m for the electrocatalytic carboxylation of (periluoroalkyl)alkenes 4. CONCLUSIONS The electrochemical incorporation of CO2 into perfluoroalkyl derivatives has b e e n e x p l o r e d in t h e case of ( p e r f l u o r o a l k y l ) a l k y l iodides and (perfluoroalkyl)alkenes, with an electrochemical system based on the use of consumable anodes combined with organometallic catalysis by nickel complexes. Iodide derivatives have been functionalized to the corresponding carboxylic acids by reductive carboxylation. Interesting and new results have been obtained from the fixation of CO2 into perfluoroalkyl olefins. Good yields of carboxylic acids could be reached by a carefull control of the reaction conditions and of the nature of the catalytic system. The main carboxylic acids are derived from the incorporation of carbon dioxide with a double bond migration and loss of one fluorine atom from the CF2 in ~ position of the double bond. The formation of carboxylic acids from perfluoroalkyl olefins reveals an important influence of the perfluoroalkyl chain on the carboxylation process. Thus, no carboxylation occurred in the case of related non-activated alkyl olefins under the same reaction conditions. These results constitute the first example in which an allylic reactivity involving a double bond migration is observed in electrochemical carboxylations.
218 REFERENCES
1.
a) E. Kissa, Fluorinated Surfactants. Synthesis, Properties, Applications, Surfactant Science Series, Vol. 50, M. Dekker, New York, 1994. b) J. G. Riess, J. Greiner and P. Vierling, In Organofluorine Compounds in Medicinal Chemistry and Biomedical Applications, R. Filler, Y. Kobayashi and L. 1Y[ Yagupolskii (eds), Elsevier, Amsterdam, London, New York, Tokyo, pp 339380, 1993. 2. M. Aresta and G. Forti (eds.), Carbon Dioxide as a Source of Carbon, Nato ASI Series, Series C, Vol. 206, Dordrecht, 1987. 3. a) H. Hoberg, Y. Peres, C. Krtiger and Y. H. Tsay, Angew. Chem., Int. Ed. Eng., 26 (1987) 771. b) D. Walther, E. Dinjus, J. Sieler and L..4~dersen, J. Organomet. Chem., 276 (1984) 99. 4. S.A. Cohen and J. E. Bercaw, Organometallics, 4 (1985) 1006. 5. H. Hoberg, K. Jenni, K. Angermund and C. Kruger, Angew. Chem., Int. Ed. Eng., 99 (1987) 141. 6. P. Binger and H. J. Weintz, Chem. Ber., 117 (1984) 654. 7. A. L. Lapidus, S. D. Pirozhkov and A. A. Koryakin, Bull. Acad. Sci. USSR., Div. Chem. Sci. (Engl. Trans), (1978) 2513. 8. H. Blancou, P. Moreau and A. Commes~as, J. Chem. Soc., Chem. Commun., (1976) 885. 9. N. Ishikawa, M. Takahashi, T. Sato and T. Kitazume, J. Fluorine Chem., 22 (1983) 585. 10. H. Lund and M. Baizer in Organic Electrochemistry, M. Dekker, New York, 3 rd Ed., 1990. 11. S. Derien, J. C. Clinet, E. Dufiach and J. P~richon, Tetrahedron, 48 (1992) 5235. 12. a) J. Chaussard, J. C. Folest, J. Y. Ndd~lec, J. P~richon, S. Sibille and M. Troupel, Synthesis, (1990) 369. b) G. Silvestri, S. Gambino, G. Filardo and A. Gulota, Angew. Chem., Int. Ed. Engl., 23 (1984) 979. 13. a) N. O. Brace, J. Org. Chem., 27 (1962) 3033. b) N. O. Brace, J. Fluorine. Chem., 20 (1982) 313. c) A. Manfredi, S. Abouhilale, J. Greiner and J. G. Riess, Bull. Soc. Chim. Fr., (1990) 872. d) D. J. Burton and L. J. Kehoe, Tetrahedron Lett., (1966) 5163. 14. S. Derien, E. Dufiach and J. P~richon, J. Am. Chem. Soc., 113 (1981) 8447. 15. S. Derien, J. C. Clinet, E. Dufiach and J. Pdrichon, J. Org. Chem., 58 (1993) 2578. 16. E. Dufiach and J. P6richon, J. Organomet. Chem., 352 (1988) 239. 17. B. Bosnich, C. I~ Poon and M. L. Tobes, Inorg. Chem., 4 (1965) 1102. 18. E. Dufiach and J. Pdrichon, Synlett, (1990) 143.