Gold(I)-Catalyzed Hydroaminative Cyclization Leading to 2,5-Dihydroisoxazole

Abstract

Gold(I)-catalyzed intramolecular hydroamination of O-propargyl-N-Boc-hydroxylamine is reported. The present ­method provides a novel, catalytic, and mild approach to 2,5-dihydroisoxazole derivatives. In addition, a mechanism of N-O cleavage as a side reaction as well as desired cyclization is proposed.

2,5-dihydroisoxazoles - heterocycles - cyclizations - gold catalysis - carbenoids

References and Notes

1a Nakamura I. Yamamoto Y. Chem. Rev.  2004,  104:  2127 

1b Freeman JP. Chem. Rev.  1983,  83:  241 

1c Kozikowski AP. Acc. Chem. Res.  1984,  17:  410 

1d Confalone PN. Ko SS. Tetrahedron Lett.  1984,  25:  947 

1e Corral JM. Gordaliza M. Castro MA. Vazquez LL. Gravalos DG. Broughton HB. Feliciano AS. Tetrahedron  1997,  53:  6555 

2 Deshong P. Li W. Kennington JW. Ammon HL. Leginus JM. J. Org. Chem.  1991,  56:  1364 

3a Aschwanden P. Frantz DE. Carreira EM. Org. Lett.  2000,  2:  2331 

3b Pinet S. Pandya SU. Chavant PY. Ayling A. Valee Y. Org. Lett.  2002,  4:  1463 

3c Cantagrel F. Pinet S. Gimbert Y. Chavant PY. Eur. J. Org. Chem.  2005,  2694 

For a similar 5-endo-dig or 6-endo-dig process, see:

4a Peng A.-Y. Ding Y.-X. J. Am. Chem. Soc.  2003,  125:  15006 

4b Patil N. Yamamoto Y. J. Org. Chem.  2004,  69:  5139 

4c Tang W. Ding Y.-X. J. Org. Chem.  2006,  71:  8489 (Pd)

4d Fukuda Y. Utimoto K. Nozaki H. Heterocycles  1987,  25:  297 

Similar Hydroamination on alkene, see:

4e Bates RW. Sa-Ei K. Org. Lett.  2002,  4:  4225 

4f Shinohara T. Arai MA. Wakita K. Arai T. Sasai H. Tetrahedron Lett.  2003,  44:  711 

5 Donati D. Fusi S. Ponticelli F. Paccani RP. Adamo MFA. Tetrahedron  2007,  63:  1583 

For the latest reviews on homogeneous gold catalysis, see:

6a Hashmi ASK. Hutchings GJ. Angew. Chem. Int. Ed.  2006,  45:  7896 

6b Jiménez-Núñez E. Echavarren AM. Chem. Commun.  2007,  333 

6c Gorin DJ. Toste FD. Nature (London)  2007,  446:  395 

6d Fürstner A. Davies PW. Angew. Chem. Int. Ed.  2007,  46:  2 

For a recent review on gold-catalyzed hydroamination, see:

7a Widenhoefer RA. Han X. Eur. J. Org. Chem.  2006,  4555 

For recent selected examples, see:

7b LaLonde RL. Sherry BD. Kang EJ. J. Am. Chem. Soc.  2007,  129:  2452 

7c Zhang Y. Donahue JP. Li C.-J. Org. Lett.  2007,  9:  627 

7d Bender CF. Widenhoefer RA. Org. Lett.  2006,  8:  5303 

7e Han X. Widenhoefer RA. Angew. Chem. Int. Ed.  2006,  45:  1747 

7f Nishina N. Yamamoto Y. Angew. Chem. Int. Ed.  2006,  45:  3314 

7g Brouwer C. He C. Angew. Chem. Int. Ed.  2006,  45:  1744 

7h Shi M. Liu L.-P. Tang J. Org. Lett.  2006,  8:  4043 

7i Liu X.-Y. Li C.-H. Che C.-M. Org. Lett.  2006,  8:  2707 

7j Kadzimirsz D. Hildebrandt D. Merz K. Dyker G. Chem. Commun.  2006,  661 

7k Zhang J. Yang C.-G. He C. J. Am. Chem. Soc.  2006,  128:  1798 

7l Morita N. Krause N. Eur. J. Org. Chem.  2006,  4634 

7m Zigang YL. Li C.-J. Org. Lett.  2005,  7:  2675 

7n Morita N. Krause N. Org. Lett.  2004,  6:  4121 

7o Mizushima E. Hayashi T. Tanaka M. Org. Lett.  2003,  5:  3349 

7p Müller TE. Grosche M. Herdtweck E. Pleier A.-K. Walter E. Yan Y.-K. Organometallics  2000,  19:  170 

8a Foot OF. Knight DW. Low ACL. Li Y. Tetrahedron Lett.  2007,  48:  647 

For other reports on halonium (X⁺)-promoted processes, see:

8b Fiumana A. Lombardo M. Trombini C. J. Org. Chem.  1997,  62:  5623 

8c Knight DW. Redfern AL. Gilmore J. J. Chem. Soc., Perkin Trans. 1  2002,  622 

9a Kang JE. Kim HB. Lee JW. Shin S. Org. Lett.  2006,  8:  3537 

9b Hashmi ASK. Rudolph M. Schymura S. Visus J. Frey W. Eur. J. Org. Chem.  2006,  4905 

10a Edwards JO. Pearson RG. J. Am. Chem. Soc.  1962,  84:  16 

10b Fina NJ. Edwards JO. Int. J. Chem. Kinet.  1973,  5:  1 

11a Yang Y.-K. Tae J. Synlett  2003,  2017 

For methods using N-hydroxyphthalimide, see:

11b Koening SG. Kristi SM. Leonard KA. Löwe RS. Chen BC. Austin DJ. Org. Lett.  2003,  5:  2203 

11c Foot OF. Knight DW. Chem. Commun.  2000,  975 

12

It is to be noted that the formed 2,5-dihydroisoxazole 2a was rather unstable and slowly decomposes into unidentified product upon keeping at r.t. for long period.

13

Representative Procedure for the Formation of 2d
To a solution of 1d (133 mg, 0.780 mmol) in CH₂Cl₂ (4 mL) was added Au(PPh₃)Cl (1.9 mg, 3.9 µmol, 0.5 mol%) and AgOTf (1 mg, 3.9 µmol), and the mixture was stirred for 2 h at r.t. After removal of solvent, the residual oil was purified by silica gel flash chromatography to afford 2d as colorless oil (90.3 mg, 68%). ¹H NMR (400 MHz, CDCl₃): δ = 6.60 (t, J = 2.2, 4.7 Hz, 1 H), 5.30 (td, J = 1.8, 4.7 Hz, 1 H), 5.03 (t, J = 2.2 Hz, 1 H), 1.54 (s, 9 H). ¹³C NMR (100 MHz, CDCl₃): δ = 151.0, 125.8, 103.2, 82.1, 75.0, 28.1. LRMS (EI): for C₈H₁₃NO₃ [M⁺]: m/z = 171; for C₇H₁₀NO₃ [M⁺ - Me]: m/z = 156; for C₇H₁₃NO [M⁺ - CO₂]: m/z = 127; for C₃H₅NO [M⁺ - t-BuOCO + H]: m/z = 71. Anal. Calcd for C₈H₁₃NO₃: C, 56.13; H, 7.65; N, 8.18. Found: C, 56.16; H, 7.47; N, 8.14.

14 Dubé P. Toste FD. J. Am. Chem. Soc.  2006,  128:  12062 

15a Gorin DJ. Davis NR. Toste FD. J. Am. Chem. Soc.  2005,  127:  11260 

15b Shapiro ND. Toste FD. J. Am. Chem. Soc.  2007,  129:  4160 

15c Witham CA. Mauleón P. Shapiro ND. Sherry BD. Toste FD. J. Am. Chem. Soc.  2007,  129:  5838 

15d Li G. Zhang L. Angew. Chem. Int. Ed.  2007,  46:  in press 

Use of N-hydroxyimides as oxidant have been reported in Ru- and Rh-carbenoids. See:

16a Trost BM. Rhee YH. J. Am. Chem. Soc.  1999,  121:  11680 

16b Trost BM. Rhee YH. J. Am. Chem. Soc.  2002,  124:  2528