” CHCl,. b 3, 4, 5, 7-Tetra-O-acetyl-2, 6-anhydro-D-urub~~ o-hept-2-enono~ t~ le.'3, 4, 5, 7- Tetra-0-acetyl-2, 6-anhydro-D-lyxo-hept-2-enononitrile. d 3, 4, 5-Tri-O-acetyl-2, 6-anhydro-D- threo-hex-2-enononit~ le.'3, 4, 5-Tri-O-acetyl-2, 6-anhydro-o-erylhro-hex-2-enononit~ le. f For comparison, see refs. 17 and 10. g See refs. 19 and 20.* See ref. 21. i 2, 3, 4-Tri-O-acetyl- D-arabinono-1, 5-lactone. j Nujol.'KBr.'Hg (CN), Me, SO. m Hg (OAc) X-Me, SO.