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An efficient synthesis of 2-deoxy-L-ribose was achieved without chromatography starting from its enantiomer 2-deoxy-D-ribose in more than 30% overall yield. An unexpected product, 2-deoxy-xylose, was obtained under slightly different reaction conditions and isolated with partial racemization. The structure of the scalemic 2-deoxy-xylose was confirmed by X-ray crystallography.

A new series of 2,2¢-(1,4-phenylene)bis(3-substituted-1H-inden-1-ones) were prepared and their structures were established by 1 H and 13 C NMR, IR, and HRMS spectroscopy. One molecular structure was further confirmed by single crystal X-ray crystallography. The synthetic mechanism was studied in detail.The key step involves the reaction of the Grignard reagent with the sodium enolate of 2,2¢-(1,4-phenylene)bis[1H-indene-1,3(2H)-dione]. This is the first example of a sodium enolate being employed as the protecting reagent for a carbonyl group in the Grignard reaction.

A mild and efficient method has been developed for the chemoselective preparation of acylals from aldehydes in the presence of catalytic amounts (0.01-1.0 mol%) of InBr 3 under solventfree conditions in very good to excellent yields.Selective protection and deprotection is the heart and soul of multistep organic synthesis. Acylals (geminal diacetates) of aldehydes have already been recognized as important protecting group alternatives to acetals 1 because of their stability in neutral and basic medium 2 and their easy conversion into the parent aldehydes. 3 In addition, acylals are useful starting materials and intermediates in organic synthesis 4 and have been used as cross linking reagents for cellulose in cotton. 5 Smonou and Angelis have reported the synthesis of optical aldehydes by lipase-catalyzed resolution of the corresponding acylals. 6 As a result, a variety of methods have been examined for their formation. Generally, acylals are prepared from aldehydes and acetic anhydride using strong protonic acids, such as sulfuric, phosphoric, methanesulfonic or perchloric acids, 7 and Lewis acids, such as zinc chloride, ferric chloride, ferrous sulfate, lithium bromide, phosphorus trichloride, tungsten hexachloride, indium chloride, ceric ammonium nitrate, lithium tetrafluoroborate, zinc tetrafluoroborate, Fe 2 (SO 4 ) 3 ·xH 2 O, zirconium chloride, copper(II) tetrafluoroborate, bismuth nitrate, 8 heteropolyacid Well-Dawson (H 6 P 2 W 18 O 62 ·24H 2 O) and aluminum dodecatungstophosphate (AlPW 12 O 40 ), 9 and heterogeneous catalysts like Nafion-H, expansive graphite, zeolites, clay and supported reagents. 10 Other catalysts, such as iodine, 11 N-bromosuccinimide, 12 trimethylchlorosilane/sodium iodide, 13 have also been used for this transformation. But these procedures are often accompanied by longer reaction times, low product yields, stringent conditions, high catalyst loading, corrosive reagents, high temperature and require the use of toxic metal ions and solvents. Although recently the triflates like Cu(OTf) 2 , Sc(OTf) 3 and LiOTf have emerged as the most effective catalysts, 14 the high cost and susceptibility to aqueous medium of the metal triflates do not make triflates good contenders for use in large scale synthesis. Therefore, mild reaction conditions that can overcome the shortcomings of previous methods are necessary.Since Li and Chan initiated and applied indium-mediated reactions in aqueous media in 1991, 15 indium complexes have emerged as mild and water-tolerant Lewis acid catalysts for organic synthesis with high chemo-, regio-and stereoselectivity. 16 Particularly, indium tribromide has been found to be a more effective catalyst than conventional Lewis acids in promoting various transformations including thioacetalization, Biginelli reaction, sulfonation of indoles, stereoselective synthesis of alkynyl sugars, nucleophilic addition, intramolecular Michael addition, synthesis of 1,3-dioxane derivatives, Ferrier rearrangement, regioselective ring opening of epoxides, conversion of oxiranes t...