Lewis acid-promoted intramolecular reactions of alkenyl ethenetricarboxylates and the corresponding amides have been examined. Reaction of allyl ethenetricarboxylates and the amides with Lewis acids (1-2 equiv) such as TiCl4, TiBr4, AlCl3, and AlBr3 gave 3,4-trans-halogenomethyl 2-oxotetrahydrofuran and pyrrolidine derivatives stereoselectively in high yields. The stereochemistries were determined by NOE experiments. Reaction of alkyl-substituted allylic ethenetricarboxylates with Lewis acids gave chloro 2-oxotetrahydrofurans and pyrans. For some alkyl-substituted substrates, cationic intermediates may be formed under the reaction conditions, and rearranged products have been obtained.

Lewis Acid-Promoted Cyclization Reactions of Alkenyl Ethenetricarboxylates: Stereoselective Synthesis of 2-Oxotetrahydrofurans and 2-Oxopyrrolidines. -(YAMAZAKI*, S.; FUJINAMI, K.; MAITOKO, Y.; UEDA, K.; KAKIUCHI, K.; J. Org. Chem. 78 (2013) 17, 8405-8416, http://dx.