The synthesis of optically active Hagemann's esters was investigated. The starting materials in this approach were enamino esters (R,Z)-8, prepared through the condensation of keto ester 6 with (R)-1-phenylethylamine 7. Michael addition reaction of the enamino esters (R,Z)-8 with methyl vinyl ketone gave the expected adducts 10 with good e.e.s of 93-96%. Subsequent annulation of the adducts furnished optically active Hagemann's esters. (C) 2001 Elsevier Science ltd. All rights reserved.
Barta, Nancy S.; Brode, Adam; Stille, John R., Journal of the American Chemical Society, 1994, vol. 116, # 14, p. 6201 - 6206
作者:Barta, Nancy S.、Brode, Adam、Stille, John R.
DOI:——
日期:——
Stereoselective Reduction of Enantiopure β-Enamino Esters by Hydride: A Convenient Synthesis of Both Enantiopure β-Amino Esters
作者:Cristina Cimarelli、Gianni Palmieri
DOI:10.1021/jo960107y
日期:1996.1.1
The reduction of enantiopure beta-enamino esters 1 with sodium triacetoxyborohydride in acetic acid is described. This occurs with good diastereo- and enantioselectivity to yield beta-amino esters 2 and 3 (after hydrogenolysis of the N-chiral group). A model is reported for the origin of the stereoselectivity through an enol ester-diacetoxyborohydride 6, which affords the intramolecular reduction. By choosing the appropriate chiral amine, this procedure allows a straightforward preparation of both the enantiopure beta-amino esters and derivatives with known biological activity, using readily available starting materials and inexpensive reagents and conditions.