Efficient Direct Alkynylation of Trifluoromethyl Ketones Catalyzed by AgF in Water and Organic Solvents

Abstract

A general and efficient method for the direct alkynylation of trifluoropyruvate and trifluoroacetophenone in water was developed by using AgF and PCy₃ as a catalyst. The ligand enhanced the catalyst activity significantly. The reaction in water is comparable to the one carried out in organic solvents.

Key words

direct alkynylation - trifluoromethyl ketones - silver fluo­ride

References and Notes

• 1 Anastas PT. Warner JC. Green Chemistry: Theory and Practice   Oxford University Press; Oxford: 1998. 
• For representative reviews, see:
• 2a Li C.-J. Chem. Rev.  2005,  105:  3095 
• 2b Li C.-J. Chan T.-H. Tetrahedron  1999,  55:  11149 
• 2c Li C.-J. Tetrahedron  1996,  52:  5643 
• 2d Chan T.-H. Isaac MB. Pure Appl. Chem.  1996,  68:  919 
• 2e Li C.-J. Chan T.-H. Organic Reactions in Aqueous Media   John Wiley and Sons; New York: 1997. 
• 2f Organic Synthesis in Water   Grieco PA. Thomson Science; Glasgow: 1998. 
• 2g Li C.-J. Chem. Rev.  1993,  93:  2023 
• 2h Li C.-J. Chan T.-H. Comprehensive Organic Reactions in Aqueous Media   John Wiley and Sons; New York: 2007. 
• 2i Organic Reactions in Water   Lindstrom UM. Blackwell Publishing; Oxford: 2007. 
• 3a Reddy MS. Narender M. Nageawar YVD. Rao KR. Synth. Commun.  2007,  37:  1983 
• 3b Li J.-M. Zha Z.-G. Sun L.-L. Zhang Y. Wang Z.-Y. Chem. Lett.  2006,  35:  498 
• 3c Chaudhuri MK. Dehury SK. Hussain S. Tetrahedron Lett.  2005,  46:  6247 
• 3d Zha Z.-G. Xie Z. Zhou C.-L. Chang M.-X. Wang Z.-Y. New J. Chem.  2003,  27:  1297 
• 3e Li C.-J. Meng Y. Yi X.-H. J. Org. Chem.  1998,  63:  7498 
• 3f Nokami J. Otera J. Sudo T. Okawara R. Organometallics  1983,  2:  191 
• 4a Issac MB. Chan T.-H. J. Chem. Soc., Chem. Commun.  1995,  1003 
• 4b Yi X.-H. Meng Y. Li C.-J. Chem. Commun.  1998,  449 
• 5a Zhou C.-L. Wang Z.-Y. Synthesis  2005,  1649 
• 5b Bieber LW. Storch EC. Malvestiti I. Sila MF. Tetrahedron Lett.  1998,  39:  9393 
• 6a Petasis NA. Zavialov IA. J. Am. Chem. Soc.  1997,  119:  445 
• 6b Ueda M. Miyaura N. J. Org. Chem.  2000,  65:  4450 
• 6c Hayashi T. Ishigedani M. J. Am. Chem. Soc.  2000,  122:  976 
• 6d Li C.-J. Meng Y. J. Am. Chem. Soc.  2000,  122:  9538 
• 7 Keh CCK. Wei C. Li C.-J. J. Am. Chem. Soc.  2003,  125:  4062 
• 8 Chan T.-H. Li C.-J. Wei Z.-Y. J. Chem. Soc., Chem. Commun.  1990,  505 
• 9a Yao X. Li C.-J. Org. Lett.  2005,  7:  4395 
• 9b Wei C. Mague JT. Li C.-J. Proc. Natl. Acad. Sci. U.S.A.  2004,  101:  5749 
• 9c Wei C. Li C.-J. J. Am. Chem. Soc.  2003,  125:  9584 
• 9d Wei C. Li Z. Li C.-J. Org. Lett.  2003,  5:  4473 
• 9e Wei C. Li C.-J. Green Chem.  2002,  4:  39 
• 9f Wei C. Li C.-J. J. Am. Chem. Soc.  2002,  124:  5638 
• 9g Li C.-J. Wei C. Chem. Commun.  2002,  268 
• 9h Zhang J. Wei C. Li C.-J. Tetrahedron Lett.  2002,  43:  5731 
• 9i Huang B. Yao X. Li C.-J. Adv. Synth. Catal.  2006,  348:  1528 
• 9j Yao X. Li C.-J. Org. Lett.  2006,  8:  1953 
• For recent examples, see:
• 10a Asano Y. Hara K. Ito H. Sawamura M. Org. Lett.  2007,  9:  3901 
• 10b Colombo F. Benaglia M. Orlandi S. Usuelli F. Celentano G. J. Org. Chem.  2006,  71:  2064 
• 10c Arimitsu S. Hammond GB. J. Org. Chem.  2006,  71:  8665 
• 10d Gommermann N. Koradin C. Polborn K. Knochel P. Angew. Chem. Int. Ed.  2003,  42:  5763 
• 10e Koradin C. Gommermann N. Polborn K. Knochel P. Chem. Eur. J.  2003,  9:  2797 
• 10f Lu G. Li X. Chan WL. Chan ASC. Chem. Commun.  2002,  172 
• 10g Chen ZL. Xiong WN. Jiang B. Chem. Commun.  2002,  2098 
• 10h Koradin C. Polborn K. Knochel P. Angew. Chem. Int. Ed.  2002,  41:  2535 
• 10i Carreira EM. Acc. Chem. Res.  2000,  33:  373 ; and references therein
• 11 For alkynylation of trifluoroacetophenone, see: Motoki R. Kanai M. Shibasaki M. Org. Lett.  2007,  9:  2997 
• 12 Hiyama T. Organo Fluorine Compounds: Chemistry and Applications   Springer; Berlin: 2000. 
• Trifluoropyruvates were used as substrates for catalytic Friedel-Crafts reactions, ene reactions, and aldol reactions. For examples, see:
• 13a Ogawa S. Shibata N. Inagaki J. Nakamura S. Toru T. Shiro M. Angew. Chem. Int. Ed.  2007,  45:  8525 
• 13b Zhao JL. Liu L. Sui Y. Liu YL. Wang D. Chen YJ. Org. Lett.  2006,  8:  6127 
• 13c Zhao JL. Liu L. Zhang HB. Wu YC. Wang D. Chen YJ. Tetrahedron Lett.  2006,  47:  2511 
• 13d Bandini M. Melloni A. Umani-Ronchi A. Angew. Chem. Int. Ed.  2004,  43:  550 
• 13e Gathergood N. Juhl K. Poulsen TB. Thordrup K. Jørgensen KA. Org. Biomol. Chem.  2004,  2:  1077 

14

Representative Experimental Procedure
A nitrogen-flushed 10 mL flask equipped with a magnetic stirrer and a septum was charged with AgF (6.3 mg, 0.05 mmol) and PCy₃ (14 mg, 0.05 mmol). Ethyl 3,3,3-trifluoro-pyruvate (85 mg, 0.5 mmol), alkyne (2 equiv), and H₂O (0.5 mL) were added by using a syringe. The reaction mixture was stirred for 1-2 d at r.t. and extracted with Et₂O. The organic solvent was evaporated and the residue was purified by column chromatography (SiO₂, hexane-EtOAc) and characterized by means of ¹H NMR, ¹³C NMR, IR, and HRMS.