Ahtruct: Samarium (II) iodide-mediated ring closures, of substituted N-propargyl substrates derived fnnn L-W&, have been used to generate a serie.8 of 2.3.4~hisubstiw pyrrolidine derivatives. It was envisaged that the work discussed in the preceding paper could be extended from aldehydealkene coupling to aldehyde-alkyne coupling reactions. l. There exist very few examples of such samarium (II)promoted reactions in the literature. The only systematic study was conducted by Shim and Ifang who examined the intramoleculsr couplings of a range of aldehyde and ketone groups with alkynes. They succeeded in generating 5 and 6-membered carbocyclic and heterccyclic products, in moderate to good yields, but observed higher yields and cleaner products in the formation of 5-membered, as compared to 6membered systems. MeO2C OTBDMS I* RF Br 'R OTBDMS -NCO2Ph 2. N-w 1 2 Scheme 1 3 L OTBDMS It was anticipated that alkynes of the type 2, prepared as shown from serine derivative 1, would give higher yields of cyclised products 3 than olefins, on treatment with samarium (II) (Scheme 1). Such products would possess functionality amenable to elaboration to kainoid analogues. which are 2,3,4-trisubstituted pyrrolidines.3 Thus Lserine 4 was converted to the protected compound 1 (Scheme 2) as described previously.l This was treated with propargyl bromide in ethyl acetate, with triethylamine as a baseP to give the monoalkylated product 5 in 36% yield. The 1H n.m.r. of the crude maction productindlcatedthattherewemsmallerquantities of the dialkylated product and some umeacted starting material. The amine was converted to aldehyde 7 by N-