Asymmetric Alkynyl Additions to Aldehydes Catalyzed by Tunable ­Oxovanadium(V) Complexes of Schiff Bases of β-Amino Alcohols

Abstract

The first example of asymmetric alkynyl additions to ­aldehydes catalyzed by oxovanadium(V) catalysts of tridentate Schiff bases of β-amino alcohols 3a-h is reported. Catalytic reactions employing the best-performing catalyst 3g furnish chiral ­propargyl alcohols in good to excellent enantioselectivities from 73% to 99% ee.

oxovanadium complex - alkynylation - Schiff bases - β-amino alcohols - aromatic aldehydes - aliphatic aldehydes - propargyl alcohols

References and Notes

1 For references, please see: Pu L. Tetrahedron  2003,  59:  9873 

2 Corey EJ. Cimprich KA. J. Am. Chem. Soc.  1994,  116:  3151 

3a Frantz DE. Fässler R. Carreira EM. J. Am. Chem. Soc.  2000,  122:  1806 

3b Jiang B. Chen Z. Xiong W. Chem. Commun.  2002,  1524 

3c Braga AL. Appelt HR. Silveira CC. Wessjohann LA. Schneider PH. Tetrahedron  2002,  58:  10413 

3d Kamble RM. Singh VK. Tetrahedron Lett.  2003,  44:  5347 

3e Makita N. Hoshino Y. Yamamoto H. Org. Biomol. Chem.  2004,  2:  3312 

3f Xu Z. Chen C. Xu J. Miao M. Yan W. Wang R. Org. Lett.  2004,  6:  1193 

3g Fang T. Du D.-M. Lu S.-F. Xu J. Org. Lett.  2005,  7:  2081 

3h Emmerson DPG. Hems WP. Davis BG. Org. Lett.  2006,  8:  207 

4 Anand NK. Carreira EM. J. Am. Chem. Soc.  2001,  123:  9687 

5 Xu M.-H. Pu L. Org. Lett.  2002,  4:  4555 

6a Lu G. Li X. Zhou Z. Chan WL. Chan ASC. Tetrahedron: Asymmetry  2001,  12:  2147 

6b Dahmen S. Org. Lett.  2004,  6:  2113 

6c Zhu M. Li X.-Z. Yuan K. Cao B.-X. Hou X.-L. Tetrahedron: Asymmetry  2004,  15:  219 

6d Kang Y.-F. Liu L. Wang R. Yan W.-J. Zhou Y.-F. Tetrahedron: Asymmetry  2004,  15:  3155 

6e Yamashita M. Yamada K.-I. Tomioka K. Adv. Synth. Catal.  2005,  347:  1649 

6f Mao J. Wan B. Wu F. Lu S. Chirality  2005,  17:  243 

6g Thoniyot CCP. Hirayama LC. Romano T. Singaram B. Tetrahedron: Asymmetry  2005,  16:  1829 

6h Pizzuti MG. Superchi S. Tetrahedron: Asymmetry  2005,  16:  2263 

7 Trost BM. Weiss AH. Wangelin AJ. J. Am. Chem. Soc.  2006,  128:  8 

8a Liu G. Li X. Chan WL. Chan ASC. Chem. Commun.  2002,  172 

8b Li X. Lu G. Kwok WH. Chan ASC. J. Am. Chem. Soc.  2002,  124:  12636 

9a Moore D. Pu L. Org. Lett.  2002,  4:  1855 

9b Gao G. Moore D. Xie R.-G. Pu L. Org. Lett.  2002,  4:  4143 

9c Liu L. Pu L. Tetrahedron  2004,  60:  7427 

10 Liu Q.-Z. Xie N.-S. Luo Z.-B. Cui X. Cun L.-F. Gong L.-Z. Mi A.-Q. Jiang Y.-C. J. Org. Chem.  2003,  68:  7921 

11 Xu Z. Wang R. Xu J. Da C.-S. Yan W.-J. Chen C. Angew. Chem. Int. Ed.  2003,  42:  5747 

12 Gao G. Wang Q. Yu X.-Q. Xie R.-G. Pu L. Angew. Chem. Int. Ed.  2006,  45:  122 

13 Takita R. Yakura K. Ohshima T. Shibasaki M. J. Am. Chem. Soc.  2005,  127:  13760 

14

General Procedures for Synthesis of Oxovanadium(V) Complexes 3a-h.
To a solution of a Schiff base (1.00 mmol) in 10 mL appropriate alcohol, VO(Oi-Pr)₃ (0.24 mL, 1.0 mmol) was added at r.t. The mixture was stirred for 1 h and the solvent was removed under reduced pressure to give a quantitative yield of the product. All compounds were characterized by ¹H NMR and ¹³C NMR spectroscopy and by elemental analyses. Two sets of NMR resonances are observed for each complex due to the presence of two isomers in solution. Spectroscopic data of complexes 3c and 3g as examples are listed in the following. The two isomers are designated as major and minor based on relative intensities of resonances. ¹H NMR spectra for the two isomers in the phenyl region are overlapped and resonances of the minor are included in data of the major.
Complex 3c: dark green solid. ¹H NMR (400 MHz, CDCl₃): δ (major, 69%) = 7.56 (s, 1 H, CH=N), 7.50-6.76 (m, Ph), 6.43 (d, J = 3.2 Hz, 1 H, CHO), 5.34-5.26 (m, 2 H, OCH ₂ ), 4.20 (d, J = 6.0 Hz, 1 H, CHN), 3.61 (dd, J = 7.6, 9.2 Hz, 1 H, CH _A H _B Ph), 2.62 (dd, J = 2.0, 9.0 Hz, 1 H, CH _A H _B Ph), 1.59 (t, J = 5.2 Hz, 3 H, CH ₃ ) ppm; δ (minor, 31%) = 7.57 (s, 1 H, CH=N), 6.65 (d, J = 3.6 Hz, 1 H, CHO), 5.40-5.36 (m, 2 H, OCH ₂ ), 4.53 (d, J = 7.2 Hz, 1 H, CHN), 2.57 (dd, J = 2.4, 9.2 Hz, 1 H, CH _A H _B Ph), 2.47 (dd, J = 7.6, 9.2 Hz, 1 H, CH _A H _B Ph), 1.69 (t, J = 4.8 Hz, 3 H, CH ₃ ) ppm. ¹³C{¹H} NMR (100 MHz, CDCl₃): δ = 163.26, 162.86, 162.71, 140.50, 137.86, 137.11, 135.82, 135.57, 132.45, 132.35, 130.19, 130.14, 128.70, 128.60, 128.55, 128.47, 127.62, 127.43, 127.01, 126.77, 126.67, 126.05, 125.95, 124.98, 119.78, 119.51, 118.84, 93.35, 90.92, 87.19, 86.39, 84.50, 79.54, 79.07, 78.62, 42.02, 36.23, 36.11, 25.58, 19.13, 17.97, 17.74. Anal. Calcd for C₂₄H₂₄NO₄V (%): C, 65.31; H, 5.48; N, 3.17. Found: C, 65.66; H, 5.08; N, 3.57.
Complex 3g: brown solid. ¹H NMR (400 MHz, CDCl₃): δ (major, 71%) = 7.45-6.77 (m, CH=N, Ph), 4.89 (d, J = 4.0 Hz, 1 H, CHN), 4.85 (ddd, J = 6.8, 11.4, 28.0 Hz, 2 H, OCH ₂), 4.05 (d, J = 12.0 Hz, 1 H, CHO), 3.83 (dd, J = 12.4, 12.4 Hz, 1 H, CH _A H _B Ph), 3.43 (d, J = 13.2 Hz, 1 H, CH _A H _B Ph), 2.16-2.06 (m, 1 H, CH₂ CH), 1.18 (s, 9 H, t-Bu), 1.03 [d, J = 6.8 Hz, 6H, CH(CH ₃ )₂] ppm; δ (minor, 29%) = 5.24 (d, J = 4.0 Hz, 1 H, CHN), 5.05 (ddd, J = 6.8, 11.0, 30.8 Hz, 2 H, OCH ₂), 4.32 (d, J = 11.6 Hz, 1 H, CHO), 3.28 (d, J = 14.0 Hz, 1 H, CH _A H _B Ph), 2.62 (dd, J = 12.4, 12.4 Hz, 1 H, CH _A H _B Ph), 2.40-2.22 (m, 1 H, CH₂CH), 1.21 (s, 9 H, t-Bu), 1.12 [d, J = 6.8 Hz, 6 H, CH(CH ₃ )₂] ppm. ¹³C{¹H} NMR (100 MHz, CDCl₃): δ = 165.18, 163.73, 161.93, 161.78, 137.98, 137.17, 135.37, 135.08, 132.25, 132.15, 130.20, 130.03, 128.44, 128.38, 126.67, 126.60, 120.01, 119.34, 119.04, 118.97, 118.64, 118.57, 98.05, 94.60, 89.84, 88.71, 83.31, 78.13, 36.77, 36.31, 35.81, 31.91, 31.60, 27.55, 27.12, 19.47, 19.41, 18.79. Anal. Calcd for C₂₄H₃₂NO₄V (%): C, 64.13; H, 7.18; N, 3.12. Found: C, 63.72; H, 7.42; N, 3.59.

15a Hartung J. Drees S. Greb M. Schimdt P. Svoboda I. Fuess B. Murso A. Stalke D. Eur. J. Org. Chem.  2003,  2388 

15b Blum SA. Bergman RC. Ellman JA. J. Org. Chem.  2003,  68:  150