TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: The compound (I) is D-erythro derivative. Preparation (claimed): Preparation of compound (I) involves reacting a tri-O-acetyl-D-glucal with N-bromosuccinimide and recovering the product; oxidizing the product and recovering (I). Preferred Definitions:    R1=H;    R2 and R6=-OC(=O)CH3;and    R5=Br.    WIDER DISCLOSURE - Also disclosed as new are furanose derivative of formula (II).    R4=H, alkoxy or substituted alkoxy;    R1 and R4=alkylidenedioxy or substituted alkylidenedioxy.    ACTIVITY - Arthropodicide; Insecticidal; Antifungal; Antibacterial; Phytotoxic and Antiinflammatory; Antibiotics; Cytostatic. Insecticidal effect of methyl 2,3:5,6-Dianhydro-beta -L-gulofuranoside compound (Ib) on adult white fly were tested as follows. (Ib) was applied 600 mu l solution on leaves of tomato plants infested with a known number of adult white fly. After 14 hours, the number of dead insects was counted. These assays were performed at 20-25 degrees C. (Ib) showed 85% control of white fly.    MECHANISM OF ACTION - None given.    SPECIFIC COMPOUNDS - 4,6-di-O-acetyl-2-bromo-2,3-dideoxy-D-erythro-hex-2-ene-1,5-lactone (Ia) is specifically claimed as (I).    EXAMPLE - N-bromosuccinimide (780 mg) was added to solution of tri-O-acetyl-D-glucal (1 g) in tetrahydrofuran (THF) (370 ml) and distilled water (92 ml). The mixture was stirred overnight at room temperature (rt). The reaction mixture was poured into water chilled at 0degrees C, followed by extraction of the mixture thus obtained with diethyl ether. The residue was then added to a suspension of 3 Angstrom molecular sieves (6.8 g) and pyridinium chlorochromate (4.4 g) in dichloromethane (20 ml). The reaction mixture was stirred at rt overnight, eluted with diethyl ether and stirred at rt for 10 minutes. The precipitate was removed by filtration and the filtrate was poured over florisil in a filter and filtered under vacuum. The colourless filtrate was concentrated under reduced pressure to give 4,6-di-O-acetyl-2-bromo-2,3-dideoxy-D-erythro-hex-2-enone-1,5-lactone compound as a syrup (760 mg, 37%).