Regioselective Allylic Amination of the Baylis-Hillman Adducts: An Easy and Practical Access to the Baylis-Hillman Adducts of N-Tosylimines

Abstract

The reaction of the in situ generated DABCO salt of Baylis-Hillman acetate and tosylamide in aqueous THF gave the Baylis-Hillman adduct of N-tosylimine in good yield. The method seems very simple and practical for the preparation of Baylis-Hillman adduct of N-tosylimine.

Key words

Baylis-Hillman adducts - N-tosylimine - DABCO - allylic amination - deracemization

References

• 1a Ciganek E. Organic Reactions   Vol. 51:  John Wiley and Sons; New York: 1997.  p.201 
• 1b Drewes SE. Roos GHP. Tetrahedron  1988,  44:  4653 
• 1c Basavaiah D. Rao PD. Hyma RS. Tetrahedron  1996,  52:  8001 
• 2a Perlmutter P. Teo CC. Tetrahedron Lett.  1984,  25:  5951 
• 2b Bertenshaw S. Kahn M. Tetrahedron Lett.  1989,  30:  2731 
• 2c Kundig EP. Xu LH. Schnell B. Synlett  1994,  413 
• 2d Richter H. Jung G. Tetrahedron Lett.  1998,  39:  2729 
• 2e Yamamoto K. Takagi M. Tsuji J. Bull. Chem. Soc. Jpn.  1988,  61:  319 
• Quite recently Balan and Adolfsson have reported the facile synthesis of the Baylis-Hillman adducts of N-tosylimines through a three-component reaction of arylaldehydes, tosylamide and a Michael acceptor, see: (f) Balan D. Adolfsson H. J. Org. Chem.  2001,  66:  6498 
• 3a Kim JN. Lee HJ. Lee KY. Kim HS. Tetrahedron Lett.  2001,  42:  3737 
• 3b Lee HJ. Kim HS. Kim JN. Tetrahedron Lett.  1999,  40:  4363 
• 3c Lee HJ. Seong MR. Kim JN. Tetrahedron Lett.  1998,  39:  6223 
• 3d Genisson Y. Massardier C. Gautier-Luneau I. Greene AE. J. Chem. Soc., Perkin Trans. 1  1996,  2869 
• 3e Li G. Kim SH. Wei H.-X. Tetrahedron  2000,  56:  719 
• 3f Kundig EP. Xu L.-H. Romanens P. Tetrahedron Lett.  1995,  36:  4047 
• 3g Takagi M. Yamamoto K. Tetrahedron  1991,  47:  8869 
• For the synthesis of N-tosylimines, see:
• 4a Jennings WB. Lovely CJ. Tetrahedron  1991,  47:  5561 
• 4b Trost BM. Marrs C. J. Org. Chem.  1991,  56:  6468 
• 4c Boger DL. Corbett WL. J. Org. Chem.  1992,  57:  4777 
• 4d Boger DL. Corbett WL. Curran TT. Kasper AM. J. Am. Chem. Soc.  1991,  113:  1713 
• 4e Sisko J. Weinreb SM. Tetrahedron Lett.  1989,  30:  3037 
• 4f Sisko J. Weinreb SM. J. Org. Chem.  1990,  55:  393 
• 4g Georg GI. Harriman GCB. Peterson SA. J. Org. Chem.  1995,  60:  7366 
• 4h Love BE. Raje PS. Williams TCII. Synlett  1994,  493 
• 5a Im YJ. Kim JM. Mun JH. Kim JN. Bull. Korean Chem. Soc.  2001,  22:  349 
• 5b Drewes SE. Horn MM. Ramesar N. Synth. Commun.  2000,  30:  1045 
• 5c Basavaiah D. Kumaragurubaran N. Tetrahedron Lett.  2001,  42:  477 
• 5d Basavaiah D. Kumaragurubaran N. Sharada DS. Tetrahedron Lett.  2001,  42:  85 
• Cyclohexene derivatives were obtained as diastereomeric mixtures from 1e and 1h via the elimination of acetic acid and concomitant Diels-Alder reaction. Diethyl 4-(1-hexenyl)-3-butyl-1-cyclohexene-1,4-dicarboxylate (for 1e) and 4-(1-hexenyl)-3-butyl-1,4-dicyano-1-cyclohexene (for 1h) were isolated in 43% and 48%, respectively, as an oil. For such reactions, see:
• 6a Poly W. Schomburg D. Hoffmann HMR. J. Org. Chem.  1988,  53:  3701 
• 6b Hoffmann HMR. Eggert U. Poly W. Angew. Chem., Int. Ed. Engl.  1987,  26:  1015 
• 6c Hoffman HMR. Weichert A. Slawin AMZ. Williams DJ. Tetrahedron  1990,  46:  5591 
• 8 Trost BM. Tsui H.-C. Toste FD. J. Am. Chem. Soc.  2000,  122:  3534 

7

Other nucleophiles can be used in the reaction such as phenols and primary nitroalkanes, which have the similar pK_a values as that of tosylamide.

9

Typical Procedure for the Formation of 3a: To a stirred solution of the Baylis-Hillman acetate 1a (496 mg, 2.0 mmol) in aq THF (10 mL, H₂O-THF, 1:1) was added DABCO (270 mg, 2.4 mmol) and stirred at r.t. for 10 min. To the reaction mixture p-toluenesulfonamide (345 mg, 2.0 mmol) was added and the whole mixture was stirred at 60-70 °C for 48 h. After the usual workup process and column chromatography (SiO₂, hexane/ether, 1:1), 3a was obtained as a white solid, 540 mg (75%); mp 100-101 °C (ref. [2a] 90-92 °C); IR (CH₂Cl₂): 3289, 1716, 1327, 1161 cm^-1; ¹H NMR (CDCl₃): δ = 1.14 (t, J = 7.2 Hz, 3 H), 2.41 (s, 3 H), 4.04 (q, J = 7.2 Hz, 2 H), 5.30 (d, J = 9.0 Hz, 1 H), 5.65 (d, J = 9.0 Hz, 1 H), 5.81 (s, 1 H), 6.21 (s, 1 H), 7.13-7.69 (m, 9 H); ¹³C NMR (CDCl₃): δ = 13.89, 21.46, 59.12, 60.97, 126.44, 127.21, 127.51, 127.66, 128.49, 129.44, 137.75, 138.75, 138.84, 143.29, 165.27; CIMS: m/z (%) = 189(92), 204(100), 205(15), 360(1) [MH⁺]. Anal. Calcd for C₁₉H₂₁NO₄S: C, 63.49; H, 5.89; N, 3.90. Found: C, 63.32; H, 5.91; N, 3.94.