Ruthenium(IV)-catalyzed markovnikov addition of carboxylic acids to terminal alkynes in aqueous medium

Organometallics

Volumn 30, Issue 4, 2011, Pages 852-862

  Cadierno, Victorio ^a   Francos, Javier ^a   Gimeno, José ^a  

^a UNIVERSITY OF OVIEDO   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

ALIPHATIC CARBOXYLIC ACIDS; AQUEOUS MEDIUM; ELECTRON DONORS; ENOL ESTERS; GOOD YIELD; GREEN REACTION MEDIUM; MONONUCLEAR SPECIES; PROPARGYLIC ALCOHOLS; TERMINAL ALKYNE;

ACETYLENE; ALCOHOLS; CARBOXYLIC ACIDS; CHLORINE COMPOUNDS; ESTERIFICATION; ESTERS; OLEFINS; RUTHENIUM;

RUTHENIUM COMPOUNDS;

EID: 79951927813     PISSN: 02767333     EISSN: 15206041     Source Type: Journal    
DOI: 10.1021/om1010325     Document Type: Article

References (163)

1. For general reviews, see: Alonso, F.; Beletskaya, I. P.; Yus, M. Chem. Rev. 2004, 104, 3079
2. Beller, M.; Seayad, J.; Tillack, A.; Jiao, H. Angew. Chem., Int. Ed. 2004, 43, 3368
3. Hintermann, L. Top. Organomet. Chem. 2010, 31, 123
4. Goossen, L. J.; Rodríguez, N.; Goossen, K. Angew. Chem., Int. Ed. 2008, 47, 3100
5. Goossen, L. J.; Goossen, K.; Rodríguez, N.; Blanchot, M.; Linder, C.; Zimmermann, B. Pure Appl. Chem. 2008, 80, 1725
6. See, for example: Ryan, S. J.; Candish, L.; Lupton, D. W. J. Am. Chem. Soc. 2009, 131, 14176
7. DeBergh, J. R.; Spivey, K. M.; Ready, J. M. J. Am. Chem. Soc. 2008, 130, 7828
8. Isambert, N.; Cruz, M.; Arévalo, M. J.; Gómez, E.; Lavilla, R. Org. Lett. 2007, 9, 4199
9. Chenevert, R.; Pelchat, N.; Jacques, F. Curr. Org. Chem. 2006, 10, 1067 and references cited therein
10. Goossen, L. J.; Paetzold, J. Angew. Chem., Int. Ed. 2004, 43, 1095
11. Urabe, H.; Suzuki, D.; Sasaki, M.; Sato, F. J. Am. Chem. Soc. 2003, 125, 4036
12. Bruneau, C.; Neveux, M.; Kabouche, Z.; Ruppin, C.; Dixneuf, P. H. Synlett 1991, 755 and references cited therein
13. Vinyl acetate, the monomeric precursor of poly(vinyl acetate) and poly(vinyl alcohol), is undoubtedly the most popular representative. Industrial production of vinyl acetate is presently based on the addition of acetic acid to ethylene catalyzed by Pd(II) under oxidative conditions: Wittcoff, H. A.; Reuben, B. G. In Industrial Organic Chemicals; Wiley-Interscience: New York, 1996; p 109. For polymerization reactions of acetoxystyrenes, see:
14. Monthéard, J. P.; Camps, M.; Seytre, G.; Guillet, J.; Dubois, J. C. Angew. Makromol. Chem. 1978, 72, 45
15. 12] as catalyst: Rotem, M.; Shvo, Y. Organometallics 1983, 2, 1689
16. Specific reviews on the ruthenium-catalyzed addition of carboxylic acids to alkynes are available: Bruneau, C. In Metal Vinylidenes and Allenylidenes in Catalysis: From Reactivity to Applications in Synthesis; Bruneau, C.; Dixneuf, P. H., Eds.; Wiley-VCH: Weinheim, Germany, 2008; p 313.
17. Bruneau, C. In Handbook of C-H Transformations: Applications in Organic Synthesis; Dyker, G., Ed.; Wiley-VCH: Weinheim, Germany, 2005; Vol. 1, p 72.
18. Fischmeister, C.; Bruneau, C.; Dixneuf, P. H. In Ruthenium in Organic Synthesis; Murahashi, S.-I., Ed.; Wiley-VCH: Weinheim, Germany, 2004; p 189.
19. Mitsudo, T.; Hori, Y.; Yamakawa, Y.; Watanabe, Y. J. Org. Chem. 1987, 52, 2230
20. Hori, Y.; Mitsudo, T.; Watanabe, Y. J. Organomet. Chem. 1987, 321, 397
21. Ruppin, C.; Dixneuf, P. H. Tetrahedron Lett. 1986, 27, 6323
22. Ruppin, C.; Dixneuf, P. H.; Lecolier, S. Tetrahedron Lett. 1988, 29, 5365
23. Philippot, K.; Devanne, D.; Dixneuf, P. H. J. Chem. Soc., Chem. Commun. 1990, 1199
24. Kabouche, Z.; Bruneau, C.; Dixneuf, P. H. Tetrahedron Lett. 1991, 32, 5359
25. Neveux, M.; Bruneau, C.; Dixneuf, P. H. J. Chem. Soc., Perkin Trans. 1 1991, 1197
26. Leadbeater, N. E.; Scott, K. A.; Scott, L. J. J. Org. Chem. 2000, 65, 3231
27. Nicks, F.; Libert, L.; Delaude, L.; Demonceau, A. Polym. Prepr. (Am. Chem. Soc. Div. Polym. Chem.) 2008, 49, 944
28. Nicks, F.; Libert, L.; Delaude, L.; Demonceau, A. Aust. J. Chem. 2009, 62, 227
29. Nicks, F.; Aznar, R.; Sainz, D.; Muller, G.; Demonceau, A. Eur. J. Org. Chem. 2009, 5020
30. Ohba, Y.; Takatsuji, M.; Nakahara, K.; Fujioka, H.; Kita, Y. Chem. Eur. J. 2009, 15, 3526
31. Neveux, M.; Seiller, B.; Hagedorn, F.; Bruneau, C.; Dixneuf, P. H. J. Organomet. Chem. 1993, 451, 133
32. Seiller, B.; Heins, D.; Bruneau, C.; Dixneuf, P. H. Tetrahedron 1995, 51, 10901
33. Bruneau, C.; Neveux-Duflos, M.; Dixneuf, P. H. Green Chem. 1999, 1, 183
34. Emme, I.; Bruneau, C.; de Meijere, A.; Dixneuf, P. H. Synlett 2000, 1315
35. Doucet, H.; Martin-Vaca, B.; Bruneau, C.; Dixneuf, P. H. J. Org. Chem. 1995, 60, 7247
36. Doucet, H.; Derrien, N.; Kabouche, Z.; Bruneau, C.; Dixneuf, P. H. J. Organomet. Chem. 1998, 551, 151
37. Doucet, H.; Höfer, J.; Derrien, N.; Bruneau, C.; Dixneuf, P. H. Bull. Soc. Chim. Fr. 1996, 133, 939
38. Emme, I.; Bruneau, C.; Dixneuf, P. H.; Militzer, H.-C.; de Meijere, A. Synthesis 2007, 3574
39. Although other ruthenium-based catalysts able to orient the addition towards the anti-Markovnikov products 4 are known, they are in general less active and/or stereoselective than Dixneuf's catalysts. In other cases, the 3 vs 4 selectivity was found to be strongly dependent on the nature of the terminal alkyne, carboxylic acid, and/or solvent employed. See for example: Gemel, C.; Trimmel, G.; Slugovc, C.; Kremel, S.; Mereiter, K.; Schmid, R.; Kirchner, K. Organometallics 1996, 15, 3998
40. Melis, K.; Samulkiewicz, P.; Rynkowski, J.; Verpoort, F. Tetrahedron Lett. 2002, 43, 2713
41. Opstal, T.; Verpoort, F. Tetrahedron Lett. 2002, 43, 9259
42. Melis, K.; Vos, D. D.; Jacobs, P.; Verpoort, F. J. Organomet. Chem. 2003, 671, 131
43. Melis, K.; Verpoort, F. J. Mol. Catal. A: Chem. 2003, 194, 39
44. Clercq, B. D.; Verpoort, F. J. Organomet. Chem. 2003, 672, 11
45. Doherty, S.; Knight, J. G.; Rath, R. K.; Clegg, W.; Harrington, R. W.; Newman, C. R.; Campbell, R.; Amin, A. Organometallics 2005, 24, 2633
46. Drozdzak, R.; Allaert, B.; Ledoux, N.; Dragutan, I.; Dragutan, V.; Verpoort, F. Adv. Synth. Catal. 2005, 347, 1721 and references cited therein
47. Pelagatti, P.; Bacchi, A.; Balordi, M.; Bolaño, S.; Calbiani, F.; Elviri, L.; Gonsalvi, L.; Pelizzi, C.; Peruzzini, M.; Rogolino, D. Eur. J. Inorg. Chem. 2006, 2422
48. Ye, S.; Leong, W. K. J. Organomet. Chem. 2006, 691, 1117
49. Yi, C. S.; Gao, R. Organometallics 2009, 28, 6585
50. Tan, S. T.; Fan, W. Y. Eur. J. Inorg. Chem. 2010, 4631
51. Yi, C. S. J. Organomet. Chem. 2011, 696, 76
52. 3)] can be completely reversed, leading predominantly to enol esters (Z)-4 instead of their expected isomers 3: Goossen, L. J.; Paetzold, J.; Koley, D. Chem. Commun. 2003, 706
53. Rideout, D. C.; Breslow, R. J. Am. Chem. Soc. 1980, 102, 7816
54. Breslow, R.; Maitra, U.; Rideout, D. C. Tetrahedron Lett. 1983, 24, 1901
55. Grieco, P. A.; Garner, P.; He, Z. Tetrahedron Lett. 1983, 24, 1897
56. Grieco, P. A.; Yoshida, K.; Garner, P. J. Org. Chem. 1983, 48, 3137
57. Breslow, R.; Maitra, U. Tetrahedron Lett. 1984, 25, 1239
58. See for example: Li, C.-J. Chem. Rev. 1993, 93, 2023
59. Lubineau, A.; Auge, J.; Queneau, Y. Synthesis 1994, 741
60. Li, C.-J.; Chan, T. H. In Organic Reactions in Aqueous Media; Wiley: New York, 1997.
61. Lindström, U. M. Chem. Rev. 2002, 102, 2751
62. Li, C.-J. Chem. Rev. 2005, 105, 3095
63. Andrade, C. K. Z.; Alves, L. M. Curr. Org. Chem. 2005, 9, 195
64. Li, C.-J.; Chen, L. Chem. Soc. Rev. 2006, 35, 68
65. Herrerías, C. I.; Yao, X.; Li, Z.; Li, C. J. Chem. Rev. 2007, 107, 2546
66. Organic Reactions in Water; Lindström, U. M., Ed.; Blackwell Publishing: Oxford, U.K., 2007.
67. Li, C.-J.; Chan, T. H. In Comprehensive Organic Reactions in Aqueous Media; Wiley-VCH: Weinheim, Germany, 2007.
68. Skouta, R. Green Chem. Lett. Rev. 2009, 2, 121
69. Handbook of Green Chemistry; Anastas, P. T.; Li, C.-J., Eds.; Wiley-VCH: Weinheim, Germany, 2010; Vol. 5.
70. Anastas, P. T.; Warner, J. C. In Green Chemistry: Theory and Practice; Oxford University Press: Oxford, U.K., 1998.
71. Anastas, P. T.; Williamson, T. C. In Green Chemistry: Frontiers in Benign Chemical Synthesis and Processes; Oxford University Press: New York, 1998.
72. Matlack, A. S. In Introduction to Green Chemistry; Marcel Dekker: New York, 2001.
73. Lancaster, M. In Handbook of Green Chemistry and Technology; Clark, J. H.; Macquarrie, D. J., Eds.; Blackwell Publishing: Abingdon, U.K., 2002.
74. Lancaster, M. In Green Chemistry: An Introductory Text; Royal Society of Chemistry: London, 2002.
75. Poliakoff, M.; Fitzpatrick, J. M.; Farren, T. R.; Anastas, P. T. Science 2002, 297, 807
76. Anastas, P. T.; Kirchhoff, M. M. Acc. Chem. Res. 2002, 35, 686
77. Sheldon, R. A.; Arends, I.; Hanefeld, In Green Chemistry and Catalysis; Wiley-VCH: Weinheim, Germany, 2007.
78. See, for example: Nelson, W. M. In Green Solvents for Chemistry: Perspectives and Practice; Oxford University Press: New York, 2003.
79. Clark, J. H.; Taverner, S. J. Org. Process Res. Dev. 2007, 11, 149
80. Kerton, F. M. In Alternative Solvents for Green Chemistry; RSC Publishing: Cambridge, U.K., 2009.
81. We note that the "green" nature of water (as a solvent for organic synthesis) is not absent of controversy. See for example: Blackmond, D. G.; Armstrong, A.; Coombe, V.; Wells, A. Angew. Chem., Int. Ed. 2007, 46, 3798
82. The term "on water", introduced by Sharpless and co-workers, is commonly used in the literature to refer to organic reactions proceeding in aqueous suspension: Narayan, S.; Muldoon, J.; Finn, M. G.; Fokin, V. V.; Kolb, H. C.; Sharpless, K. B. Angew. Chem., Int. Ed. 2005, 44, 3275
83. For recent reviews on organic synthesis "on water", see: Chanda, A.; Fokin, V. V. Chem. Rev. 2009, 109, 725
84. Butler, R. N.; Coyne, A. G. Chem. Rev. 2010, 110, 6302
85. See for example: Kalck, P.; Monteil, F. Adv. Organomet. Chem. 1992, 34, 219
86. Herrmann, W. A.; Kohlpaintner, C. W. Angew. Chem., Int. Ed. Engl. 1993, 32, 1524
87. Aqueous Organometallic Chemistry and Catalysis; Horváth, I. T.; Joó, F., Eds.; Kluwer: Dordrecht, The Netherlands, 1995.
88. Aqueous-Phase Organometallic Catalysis: Concepts and Applications; Cornils, B.; Herrmann, W. A., Eds.; Wiley-VCH: Weinheim, Germany, 1998.
89. Hanson, B. E. Coord. Chem. Rev. 1999, 185-186, 795
90. Aqueous Organometallic Catalysis; Horváth, I. T.; Joó, F., Eds.; Kluwer: Dordrecht, The Netherlands, 2001
91. Pinault, N.; Bruce, D. W. Coord. Chem. Rev. 2003, 241, 1
92. The use of water-saturated organic solvents has led in some cases to a beneficial impact on the reaction rates. See ref 8i and: Willem, Q.; Nicks, F.; Sauvage, X.; Delaude, L.; Demonceau, A. J. Organomet. Chem. 2009, 694, 4049
93. 2], has been described. (11k)
94. Catalytic transformations of alkynes in water have been recently reviewed: Chen, L.; Li, C.-J. Adv. Synth. Catal. 2006, 348, 1459
95. Li, C.-J. Acc. Chem. Res. 2010, 43, 581
96. The metal-catalyzed hydration of terminal alkynes to afford aldehydes (anti-Markovnikov addition) or ketones (Markovnikov addition) is a well-known and widely studied transformation of significant synthetic utility. For reviews on this topic see ref 1 and: Hintermann, L.; Labonne, A. Synthesis 2007, 1121
97. Cadierno, V.; García-Garrido, S. E.; Gimeno, J. Chem. Commun. 2004, 232
98. Cadierno, V.; Crochet, P.; García-Garrido, S. E.; Gimeno, J. Dalton Trans. 2004, 3635
99. Cadierno, V.; García-Garrido, S. E.; Gimeno, J.; Nebra, N. Chem. Commun. 2005, 4086
100. Cadierno, V.; García-Garrido, S. E.; Gimeno, J.; Varela-Álvarez, A.; Sordo, J. A. J. Am. Chem. Soc. 2006, 128, 1360
101. Díaz-Álvarez, A. E.; Crochet, P.; Zablocka, M.; Duhayon, C.; Cadierno, V.; Gimeno, J.; Majoral, J. P. Adv. Synth. Catal. 2006, 348, 1671
102. Crochet, P.; Díez, J.; Fernández-Zúmel, M. A.; Gimeno, J. Adv. Synth. Catal. 2006, 348, 93
103. Cadierno, V.; Francos, J.; Gimeno, J.; Nebra, N. Chem. Commun. 2007, 2536
104. Cadierno, V.; Gimeno, J.; Nebra, N. Chem. Eur. J. 2007, 13, 6590
105. Díaz-Álvarez, A. E.; Crochet, P.; Zablocka, M.; Duhayon, C.; Cadierno, V.; Majoral, J. P. Eur. J. Inorg. Chem. 2008, 786
106. Cadierno, V.; Francos, J.; Gimeno, J. Chem. Eur. J. 2008, 14, 6601
107. Cadierno, V.; Crochet, P.; Gimeno, J. Synlett 2008, 1105
108. Cadierno, V.; Crochet, P.; Francos, J.; García-Garrido, S. E.; Gimeno, J.; Nebra, N. Green Chem. 2009, 11, 1992
109. Cadierno, V.; Francos, J.; Gimeno, J. Green Chem. 2010, 12, 135
110. Cadierno, V.; Francos, J.; Gimeno, J. Chem. Commun. 2010, 46, 4175
111. Cadierno, V.; Díez, J.; Francos, J.; Gimeno, J. Chem. Eur. J. 2010, 16, 9808
112. García-Garrido, S. E.; Francos, J.; Cadierno, V.; Basset, J. M.; Polshettiwar, V. ChemSusChem 2011, (DOI: 10.1002/cssc.201000280).
113. Lastra-Barreira, B.; Francos, J.; Crochet, P.; Cadierno, V. Green Chem. 2011, (DOI: 10.1039/c0gc00417k).
114. 2O with isoprene: Porri, L.; Gallazzi, M. C.; Colombo, A.; Allegra, G. Tetrahedron Lett. 1965, 47, 4187
115. Salzer, A.; Bauer, A.; Podewils, F. In Synthetic Methods of Organo-metallic and Inorganic Chemistry; Herrmann, W. A., Ed.; Thieme Verlag: Stuttgart, Germany, 2000; Vol. 9, pp 36-38.
116. Salzer, A.; Bauer, A.; Geyser, S.; Podewils, F.; Turpin, G. C.; Ernst, R. D. Inorg. Synth. 2004, 34, 59-65
117. Cadierno, V.; García-Garrido, S. E.; Gimeno, J. J. Am. Chem. Soc. 2006, 128, 15094
118. Cadierno, V.; Francos, J.; García-Garrido, S. E.; Gimeno, J. Green Chem. Lett. Rev. 2010, in press.
119. 2] (5), see: Cadierno, V.; Crochet, P.; García-Garrido, S. E.; Gimeno, J. Curr. Org. Chem. 2006, 10, 165
120. Competitive dimerization of the alkyne has been previously observed in related ruthenium-catalyzed addition processes. See, for example, refs 8i, 11d, and 21a. Formation of dienyl esters (alkyne/carboxylic acid 2/1 adducts) was not detected by GC/MSD: Le Paih, J.; Monnier, F.; Dérien, S.; Dixneuf, P. H.; Clot, E.; Eisenstein, O. J. Am. Chem. Soc. 2003, 125, 11964
121. With the exception of 6h (see the Experimental Section), the preparation of these mononuclear complexes has been previously described in the literature. In all cases equatorial adducts are exclusively formed: Head, R. A.; Nixon, J. F.; Swain, J. R.; Woodard, C. M. J. Organomet. Chem. 1974, 76, 393
122. Cox, D. N.; Roulet, R. J. Chem. Soc., Chem. Commun. 1988, 951
123. Cox, D. N.; Roulet, R. Inorg. Chem. 1990, 29, 1360
124. Cox, D. N.; Small, R. W. H.; Roulet, R. J. Chem. Soc., Dalton Trans. 1991, 2013
125. Steed, J. W.; Tocher, D. A. J. Organomet. Chem. 1994, 471, 221
126. Wache, S.; Herrmann, W. A.; Artus, G.; Nuyken, O.; Wolf, D. J. Organomet. Chem. 1995, 491, 181
127. Glander, S. C.; Nuyken, O.; Schattenmann, W. C.; Herrmann, W. A. Macromol. Symp. 1998, 127, 67
128. Werner, H.; Stüer, W.; Jung, S.; Weberndörfer, B.; Wolf, J. Eur. J. Inorg. Chem. 2002, 1076
129. See also refs 24d, 24o, and 24q.
130. 16)] (its preparation and characterization are described in the Experimental Section) as catalyst resulted in remarkably lower yields, without improving the selectivity toward the anti-Markovnikov product 4aa. Thus, under the same reaction conditions, only 33% conversion was observed after 24 h of heating, giving to a 3aa /(E)-4aa /(Z)-4aa mixture in ca. 1/1/1 ratio. This fact suggests that coordination of the benzoate anion to ruthenium does not occur during the catalytic event.
131. See, for example: Dwards, T.; Paetzold, E.; Oehme, G. Angew. Chem., Int. Ed. 2005, 44, 7174
132. Zhang, J.; Meng, X.-G.; Zheng, X.-C.; Yu, X.-Q. Coord. Chem. Rev. 2009, 253, 2166
133. Cavarzan, A.; Scarso, A.; Strukul, G. Green Chem. 2010, 12, 790
134. -3 M, respectively. The use of 0.01 M solutions of these surfactants assures the correct formation of micelles: Fendler, J. H.; Fendler, E. J. In Catalysis in Micellar and Macromolecular Systems; Academic Press: New York, 1975.
135. Furton, K.; Norelus, A. J. Chem. Educ. 1993, 70, 254 Under these reaction conditions both the organometallic catalyst 6a and the organic substrates are completely soluble in the aqueous phase.
136. This negative effect is particularly marked for CTABr, probably due to the presence of an excess of bromide anions in the reaction medium that compete with the alkyne for coordination to the metal center.
137. This fact is in accord with the higher tendency of aromatic alkynes to undergo the -alkyne-to-vinylidene rearrangement. For reviews on the chemistry of transition-metal vinylidene complexes, see: Bruce, M. I. Chem. Rev. 1991, 91, 197
138. Puerta, M. C.; Valerga, P. Coord. Chem. Rev. 1999, 193-195, 977
139. Wakatsuki, Y. J. Organomet. Chem. 2004, 689, 4092
140. Cadierno, V.; Gamasa, M. P.; Gimeno, J. Coord. Chem. Rev. 2004, 248, 1627
141. Lynnam, J. M. Chem. Eur. J. 2010, 16, 8238
142. Although rare, ruthenium-catalyzed additions of carboxylic acids to internal alkynes are known. See, ref 5 and: Rotem, M.; Shvo, Y. J. Organomet. Chem. 1993, 448, 189
143. Kabouche, A.; Kabouche, Z.; Bruneau, C.; Dixneuf, P. H. J. Soc. Alger. Chim. 1999, 9, 141
144. Karabulut, S.; Öztürk, B. Ö; Imamoǧlu, Y. J. Organomet. Chem. 2010, 695, 2161 We assume that in our case the greater steric hindrance between the internal-alkyne substituents and the ancillary triphenylphosphine ligand prevent the coordination of the C-C bond to the metal center.
145. Devanne, D.; Ruppin, C.; Dixneuf, P. H. J. Org. Chem. 1988, 53, 925
146. Bruneau, C.; Kabouche, Z.; Neveux, M.; Seiller, B.; Dixneuf, P. H. Inorg. Chim. Acta 1994, 222, 154
147. Darcel, C.; Bruneau, C.; Dixneuf, P. H.; Neef, G. J. Chem. Soc., Chem. Commun. 1994, 333
148. Costin, S.; Rath, N. P.; Bauer, E. B. Adv. Synth. Catal. 2008, 350, 2414
149. Heitt, N. P.; Lynam, J. M.; Welby, C. E.; Whitwood, A. C. J. Organomet. Chem. 2011, 696, 378
150. Ruthenium-catalyzed anti-Markovnikov additions of carboxylic acids to terminal propargylic alcohols are rare: Picquet, M.; Fernández, A.; Bruneau, C.; Dixneuf, P. H. Eur. J. Org. Chem. 2000, 2361
151. Berger, S.; Haak, E. Tetrahedron Lett. 2010, 51, 6630
152. 2CPh) remained unchanged after 12 h of heating in water at 60 °C in the presence of 6a (2 mol %): Huang, X.; de Haro, T.; Nevado, C. Chem. Eur. J. 2009, 15, 5904
153. For reviews on the chemistry of transition-metal allenylidene complexes, see: Bruce, M. I. Chem. Rev. 1998, 98, 2797
154. Cadierno, V.; Gamasa, M. P.; Gimeno, J. Eur. J. Inorg. Chem. 2001, 571
155. Cadierno, V.; Crochet, P.; Gimeno, J. In Metal Vinylidenes and Allenylidenes in Catalysis: From Reactivity to Applications in Synthesis; Bruneau, C.; Dixneuf, P. H., Eds.; Wiley-VCH: Weinheim, Germany, 2008; p 61.
156. Cadierno, V.; Gimeno, J. Chem. Rev. 2009, 109, 3512
157. Cadierno, V.; García-Garrido, S. E. Top. Organomet. Chem. 2010, 30, 151
158. 3)] (2 mol %) is able to generate the enol ester 3aa, by selective Markovnikov addition of benzoic acid (2a) to 1-hexyne (1a), in 94% GC yield after 4 h of heating (to be compared with entry 1 in Table 1). Full details will be presented in due course.
159. Yamaguchi, I.; Osakada, K.; Yamamoto, T. Macromolecules 1994, 27, 1112
160. Kabouche, A.; Kabouche, Z.; Bruneau, C.; Dixneuf, P. H. J. Chem. Res., Miniprint 1999, 1247
161. J. Chem. Res., Synop. 1999, 249.
162. Stevens, C. L.; Malik, W.; Pratt, R. J. Am. Chem. Soc. 1950, 72, 4758
163. Rubin, M. B.; Inbar, S. J. Org. Chem. 1988, 53, 3355