sample was obtained by preparative TLC @io2, hexanelethyl acetate, 411, R 0.16. Anal. Calcd for CdS2N2O5: C, 69.01; H, 7.13; N, 6.19. dound C, 68.75; H, 7.21; N, 6.33.The racemic mixture was separated on a Daicel CHIRALCEL OJ column using 2% ethanol in hexane solvent with a flow rate of 1 mL/min. The enantiomers eluted approximately at 32 and 50 min, at ca. 50 OC. Enantiomeric purity was checked by reinjection after fraction collection. Within the limits of detection, the fractions were single enantiomers.The procedures for X-ray crystaUosraphv and radioligand b i n d i n p have been described previously, and are detailed in (25) Campana, C. F.; Shepard, D. F.; Litchman, W. M. Znorg. Chem. 1980,20,4039. (26) Sheldrick, G. SHELXTL, revision 4.1 (1984); Nicolet XRD Corporation: Madieon, WI, 1984. (27) (a) Bolger, G. T.; Gengo, P.; Klowckomki, R.; Luchoweki, E.; Siegel, H.; J d , R A; Triggle, A. M.; Triggle, D. J. J. Pharmcrcol. Exp. Ther. lSS9,225,291. (b) J d , R. A.; Sarmiento, J. G.; Maurer, S. C.; Bolger, G. T.; Triggle, D. of theWaehingtan State University X-ray facility. We also thank the NSF (Grant CHE-8408407) and the Boeing Co, for funds which helped establish the WSU X-ray facility.Supplementary Material Available: 2D NOESY spectrum of 1, molecular mechanics calculations (including Cartesian coordinates) of 2-and E-1, tables of X-ray data for IDHP 6 (atomic coordinate and isotropic thermal parametars, bond lengths, bond anglea, and anisotropic thermal parameters, H atom coordinatea), molecular mechanics calculation for 5, and NOESY spectrum of 6 (20 pages). This material is contained in many libraries on microfiche, immediately follow thie article in the microfii version of the journal, and can be ordered from the ACS; we any current masthead page for ordering information.A convergent, one-pot construction of functionalized pyrrolidine ring systems has been developed. The method is based on a tandem Michael reaction initiated by an intermolecular conjugate addition of a nitrogen nucleophile to an electrophilic olefin followed by trapping of the generated enolate by a built-in a,b-uneaturated acceptor. After model studiea verified the feasibility of the proceee and gave information about ita stereochemical outcome, the strategy was succeeafdly applied to kainoid synthesis. The construction of the basic pyrrolidine skeleton of all the members of the family requirea coupling of a suitable electrophilic subunit with a common donor-acceptor fragment containing the nitrogen nucleophile. Thus, the enantioselective synthesis of (+)-a-allokainic acid (2) and the formal synthesis of ita C-4 epimer (-)-a-kainic acid (11, have been accompliehed wing methyl vinyl ketone and 2-nitro-3-methyl-1,3-butadiene, respectively, as electrophilic partners of (s)a-(benzylamino)-5-hydroxy-2pentenoic acid ethyl ester (LI), easily derived in six steps from &serine. Although the acetyl group of methyl vinyl ketone is a logical precursor to the isopropenyl moiety of 2, the use of the nitmbutadiene is more appropriata for the synthesi...
