Silver-Catalyzed C-H Insertion Reactions with Donor-Acceptor Diazoacetates

Abstract

In this paper we describe the first examples of carbene transfer with donor-acceptor diazoacetates and the silver tris(pyrazolyl)borate complex {HB[3,5-(CF₃)₂Pz]₃}Ag(THF). These reactions generally proceed in good yields and exhibit improved selectivities compared to simple diazoacetates.

Key words

organometallic - tris(pyrazolyl)borate - silver - atom transfer - chemoselective

References and Notes

• 1a Davies HML. Manning JR. Nature (London)  2008,  451:  417 
• 1b Skouta R. Li C.-J. Tetrahedron  2008,  64:  4917 
• 1c Kuninobu Y. Nishina Y. Kawata A. Shouho M. Takai K. Pure Appl. Chem.  2008,  80:  1149 
• 1d Herrerias CI. Yao X. Li Z. Li C.-J. Chem. Rev.  2007,  107:  2546 
• 1e Ferreira EM. Zhang H. Stoltz BM. Tetrahedron  2008,  64:  5987 
• 1f Diaz-Requejo MM. Perez PJ. Chem. Rev.  2008,  108:  3379 
• 1g Diaz-Requejo MM. Belderrain TR. Nicasio MC. Perez PJ. Dalton Trans.  2006,  5559 
• 1h Dias HVR. Lovely CJ. Chem. Rev.  2008,  108:  3223 
• 1i Davies HML. Loe O. Synthesis  2004,  2595 
• 1j Davies HML. Angew. Chem. Int. Ed.  2006,  45:  6422 
• 2a Du Bois J. Chemtracts  2006,  18:  1 
• 2b Zalatan DN. Du Bois J. J. Am. Chem. Soc.  2008,  130:  9220 
• 2c Fiori KW. Du Bois J. J. Am. Chem. Soc.  2007,  129:  562 
• 3a Taber DF. Tian W. J. Org. Chem.  2007,  72:  3207 
• 3b Taber DF. Joshi PV. J. Org. Chem.  2004,  69:  4276 
• 4a Daugulis O. Zaitsev VG. Shabashov D. Pham Q.-N. Lazareva A. Synlett  2006,  3382 
• 4b Do H.-Q. Daugulis O. J. Am. Chem. Soc.  2007,  129:  12404 
• 4c Chiong HA. Pham Q.-N. Daugulis O. J. Am. Chem. Soc.  2007,  129:  9879 
• 4d Zaitsev VG. Shabashov D. Daugulis O. J. Am. Chem. Soc.  2005,  127:  13154 
• 4e Shabashov D. Daugulis O. Org. Lett.  2005,  7:  3657 
• 5a Kalyani D. Dick AR. Anani WQ. Sanford MS. Tetrahedron  2006,  62:  11483 
• 5b Kalyani D. Dick AR. Anani WQ. Sanford MS. Tetrahedron  2006,  62:  11483 
• 5c Desai LV. Hull KL. Sanford MS. J. Am. Chem. Soc.  2004,  126:  9542 
• 5d Dick AR. Hull KL. Sanford MS. J. Am. Chem. Soc.  2004,  126:  2300 
• 5e Kalyani D. Deprez NR. Desai LV. Sanford MS. J. Am. Chem. Soc.  2005,  127:  7330 
• 6a Campeau L.-C. Fagnou K. Chem. Commun.  2006,  1253 
• 6b Campeau L.-C. Fagnou K. Chem. Soc. Rev.  2007,  36:  1058 
• 6c Campeau L.-C. Stuart DR. Fagnou K. Aldrichimica Acta  2007,  40:  35 
• 6d Liegault B. Fagnou K. Organometallics  2008,  27:  4841 
• 6e Campeau L.-C. Schipper DJ. Fagnou K. J. Am. Chem. Soc.  2008,  130:  3266 
• 7a Chen MS. White MC. Science  2007,  318:  783 
• 7b Reed SA. White MC. J. Am. Chem. Soc.  2008,  130:  3316 
• 7c Delcamp JH. White MC. J. Am. Chem. Soc.  2006,  128:  15076 
• 8 Dias HVR. Jin W. Inorg. Chem.  1996,  35:  267 
• 9 For related work with other silver tris(pyrazolyl)borates, see: Urbano J. Belderrain TR. Nicasio MC. Trofimenko S. Diaz-Requejo MM. Perez PJ. Organometallics  2005,  24:  1528 
• 10 Lovely CJ. Browning RG. Badarinarayana V. Dias HVR. Tetrahedron Lett.  2005,  46:  2453 
• 11 Krishnamoorthy P. Browning RG. Singh S. Sivappa R. Lovely CJ. Dias HVR. Chem. Commun.  2007,  731 
• 12 Dias HVR. Browning RG. Polach SA. Diyabalanage HV. Lovely CJ. J. Am. Chem. Soc.  2003,  125:  9270 
• 13a Dias HVR. Browning RG. Richey SA. Lovely CJ. Organometallics  2004,  23:  1200 
• 13b Dias HVR. Browning RG. Richey SA. Lovely CJ. Organometallics  2005,  24:  5784 
• 14 Davies HML. Hansen T. Churchill MR. J. Am. Chem. Soc.  2000,  122:  3063 
• 15 Manning JR. Davies HML. Org. Synth.  2007,  84:  334 
• 16 Thompson JL. Davies HML. J. Am. Chem. Soc.  2007,  129:  6090 
• 17 Choi MK.-W. Yu W.-Y. So M.-H. Zhou C.-Y. Deng Q.-H. Che C.-M. Chem. Asian J.  2008,  3:  1256 
• 19 Davies HML. Hansen T. J. Am. Chem. Soc.  1997,  119:  9075 

18

General Procedure for Catalysis by Carbene-Transfer Reactions with Catalyst {HB[3,5-(CF ₃ ) ₂ Pz] ₃ }Ag(THF): Methyl phenyldiazoacetate or methyl styryldiazoacetate (0.25 mmol) dissolved in the substrate (5 mL) was added by syringe pump over a period of ca. 3 h to a stirred solution of the catalyst (0.005 g, 0.01 mmol) in the substrate (10 mL) in a foil-shielded, round-bottomed flask. The resulting mixture was stirred for 6 h at r.t., concentrated and the residue was purified by flash chromatography on silica gel (2% Et₂O-PE for hydrocarbons, 5-20% Et₂O-PE for ethers) to yield oily transparent or white solid products. The isolated yields are based on the average of at least two experiments and on the amount of diazoacetate used.

20

Methyl 2-Phenyl-3-methylhexanoate: yield: 40.2 mg (73%); diastereoisomer ratio = 1.2:1. ^¹H NMR (300 MHz, CDCl₃): δ = 7.19-7.36 (m, 10 H, ArH), 3.624 (s, 3 H, OMe), 3.620 (s, 3 H, OMe), 3.24 (d, J = 10.7 Hz, 1 H, CHPh), 3.23 (d, J = 10.3 Hz, 1 H, CHPh), 2.11-2.28 (m, 2 H, CH), 1.01-1.50 (m, 8 H, CH₂), 0.98 (d, J = 6.5 Hz, 3 H, Me), 0.89 (t, J = 6.9 Hz, 3 H, Me), 0.73 (t, J = 6.9 Hz, 3 H, Me), 0.65 (d, J = 6.9 Hz, 3 H, Me). ^¹³C NMR (125 MHz, CDCl₃): δ = 174.54, 174.49, 138.19, 138.14, 128.61, 128.58, 128.42, 128.39, 127.14, 58.8, 55.5, 51.7, 37.6, 36.2, 36.1, 35.6, 19.9, 19.4, 17.8, 16.6, 14.2, 14.0. IR (neat): 3087, 3064, 3029, 2959, 2932, 2873, 1738 cm^-¹. HRMS (ESI): m/z [M + H]⁺ calcd for C₁₄H₂₁O₂: 221.1536; found: 221.1537.