Nucleophilic addition (Nu-Mf) to isolevoglucosenone 1 generates enolates stereospecifically (exo face addition) that can be reacted with sugar-derived aldehydes to give C(1-->3)-linked disaccharide precursors with high diastereoselectivity. Limitations of the method arising from unfavorable aldolate stability can be overcome by using Et2AlI as the nucleophile. This leads to products of Baylis-Hillmann condensations. One example is presented and has led to the preparation of 2,3-anhydro-3-C-[(1S)-2,6-anhydro-D-glycero-D-gulo-heptitol-1-C-yl]-beta -D-gulo-pyranose 5. (C) 2000 Elsevier Science Ltd. All rights reserved.