1,2-Seleno Migrations in Carbohydrate Chemistry: Solution and Solid-Phase Synthesis of 2-Deoxy Glycosides, Orthoesters, and Allyl Orthoesters We thank Drs. D. H. Huang and G. Siuzdak for NMR spectroscopic and mass spectrometric assistance, respectively. We gratefully thank Nicolas Winssinger for helpful discussions and preparation of the selenium bromide resin. This work was financially supported by the Skaggs Institute for Chemical Biology, the National Institutes of Health (USA), postdoctoral fellowships from M.E.C., Spain (R.M.R., Fullbright), the Japan Society for the Promotion of Science (H.S.), the George Hewitt Foundation (K.C.F.), and grants from Schering Plough, Pfizer, Glaxo, Merck, Hoffmann - La Roche, DuPont, Abbott Laboratories, and Boehringer - Ingelheim.