A Homo-Proline Tetrazole as an Improved Organocatalyst for the Asymmetric Michael Addition of Carbonyl Compounds to Nitro-Olefins

Abstract

A new homo-proline tetrazole derivative 7 has been prepared and shown to have improved properties for achieving asymmetric Michael addition of carbonyl compounds to nitro-olefins.

Key words

asymmetric - nitro-Michael - organocatalysis - homo-proline - tetrazole

References

• 1 Dalko PI. Moisan L. Angew. Chem. Int. Ed.  2004,  43:  5138 
• 2a List B. Tetrahedron  2002,  58:  5573 
• 2b Notz W. Tanaka F. Barbas CF. Acc. Chem. Res.  2004,  37:  580 
• 3a Hajos ZG. Parrish DR. Angew. Chem., Int. Ed. Engl.  1974,  39:  1615 
• 3b Eder U, Wiechert R, and Sauer G. inventors; German Patent DE  2014757. 
• 3c Eder U. Sauer G. Wiechert R. J. Org. Chem.  1971,  10:  496 
• 3d Hajos ZG, and Parrish DR. inventors; German Patent DE  2102623. 
• 3e Recent selected examples: Chandrasekhar S. Narsihmulu C. Reddy NR. Sultana SS. Chem. Commun.  2004,  2450 
• 3f See also: Saito S. Yamamoto H. Acc. Chem. Res.  2004,  37:  570 
• 3g Ward DE. Jheengut V. Tetrahedron Lett.  2004,  45:  8347 
• 3h List B. Pojarliev P. Castello C. Org. Lett.  2001,  3:  573 
• 3i List B. Hoang L. Martin HJ. Proc. Nat. Acad. Sci. U.S.A.  2004,  101:  5389 
• 4a Watanabe S.-i. Cordova A. Tanaka F. Barbas CF. Org. Lett.  2002,  4:  4519 
• 4b Chowdari NS. Suri JT. Barbas CF. Org. Lett.  2004,  6:  2507 
• 4c Notz W. Kandasamy S. Bui T. Zhong G. Barbas CF. Tetrahedron Lett.  2001,  42:  199 
• 4d Cordova A. Barbas CF. Tetrahedron Lett.  2002,  43:  7749 
• 4e Cordova A. Barbas CF. Tetrahedron Lett.  2003,  44:  1923 
• 4f Hayashi Y. Tsuboi W. Ashimine I. Urushima T. Shoji M. Sakai K. Angew. Chem. Int. Ed.  2003,  42:  3677 
• Selected examples:
• 5a Wang W. Wang J. Li H. Tetrahedron Lett.  2004,  45:  7243 
• 5b Momiyama N. Yamamoto H. J. Am. Chem. Soc.  2003,  125:  6038 
• 5c Wang W. Li H. Wang J. Liao L. Tetrahedron Lett.  2004,  45:  8229 
• 5d Brochu MP. Brown SP. MacMillan DWC. J. Am. Chem. Soc.  2004,  126:  4108 
• 5e Kumaragurubaran N. Zhuang W. Bøgevig A. Jørgensen KA. J. Am. Chem. Soc.  2002,  124:  6254 
• 6a Cobb AJA. Shaw DM. Ley SV. Synlett  2004,  558 
• 6b Torii H. Nakadai M. Ishihara K. Saito S. Yamamoto H. Angew. Chem. Int. Ed.  2004,  43:  1983 
• 6c Momiyama N. Torii H. Saito S. Yamamoto H. Proc. Natl. Acad. Sci. U.S.A.  2004,  101:  5374 
• 6d Yamamoto Y. Momiyama N. Yamamoto H. J. Am. Chem. Soc.  2004,  126:  5962 
• 6e Hartikka A. Arvidsson PI. Tetrahedron: Asymmetry  2004,  15:  1831 
• 7a Cobb AJA. Longbottom DA. Shaw DM. Ley SV. Chem. Commun.  2004,  1808 
• 7b Cobb AJA. Shaw DM. Longbottom DA. Gold JB. Ley SV. Org. Biol. Chem.  2005,  3:  84 
• 8a List B. Pojarliev P. Martin HJ. Org. Lett.  2001,  3:  2423 
• 8b Betancort JM. Barbas CF. Org. Lett.  2001,  3:  3737 
• 8c Betancort JM. Sakthivel K. Thayumanavan R. Barbas CF. Tetrahedron Lett.  2001,  42:  4441 
• 8d Andrey O. Alexakis A. Bernardinelli G. Org. Lett.  2003,  5:  2559 
• 8e Betancort JM. Sakthivel K. Thayumanavan R. Tanaka F. Barbas CF. Synthesis  2004,  1509 
• 8f Andrey O. Vidonne A. Alexakis A. Tetrahedron Lett.  2003,  44:  7901 
• 8g Mase N. Thayumanavan R. Tanaka F. Barbas CF. Org. Lett.  2004,  6:  2527 
• 8h Fonseca MTH. List B. Angew. Chem. Int. Ed.  2004,  43:  3958 
• 8i Ishii T. Fujioka S. Sekiguchi Y. Kotsuki H. J. Am. Chem. Soc.  2004,  126:  9558 
• 8j Andrey O. Alexakis A. Tomassini A. Bernardinelli G. Adv. Synth. Catal.  2004,  346:  1147 ; and references therein
• 10 Enders D. Seki A. Synlett  2002,  26 
• 11 Alexakis A. Andrey O. Org. Lett.  2002,  4:  3611 

9

Typical Experimental Procedure.
To a suspension of catalyst (15 mol%) and nitro-olefin (0.5 mmol) in an i-PrOH-EtOH mix (1:1, 2 mL) was added ketone (0.75 mmol, 1.5 equiv) and the resulting mixture stirred at 20 °C for 24 h. After this time the reaction was quenched with sat. NH₄Cl (2 × 20 mL) and the aqueous phase extracted with EtOAc (2 × 25 mL). The combined organic layers were dried (MgSO₄), filtered and evaporated to give a residue which was further purified by flash column chromatography using EtOAc and petroleum ether 40-60 as eluent.

12

This was proven by comparison of chiral HPLC retention times and also by an inversion of sign in the optical rotation as compared to literature.