Of L-idose

Most substrates, with the exception of hydroxypymvate, have a threo configuration of hydroxyl groups at the C-3 and C-4 positions (139). The new stereocenter formed in TK-catalyzed addition is formed in the threo configuration with high diastereo-selectivity (151). Using TK-catalyzed condensations of hydroxypymvic acid with a number of aldehydes a practical preparative synthesis of L-idose [5934-56-5], L-gulose [6027-89-0], 2-deoxy-L-xylohexose, and... 

The simplified preparations128 of 5-O-sulfonylated derivatives of 1,2-O-isopropylidene-a-D-gIucofuranose (77 and 78) (see Section VI,4) was the key to substantial improvements in the synthesis of L-idose. 

G. E. Driver and J. D. Stevens, Septanose carbohydrates. III. Oxidation-reduction products from 1,2-3,4-di-O-isopropylidene-a-D-glucoseptanose Preparation of L-idose derivatives, Aust. J. Chem., 43 (1990)2063-2081. 

D. Horton and J.-H. Tsai, Preparation of derivatives of L-idose and L-iduronic acid from 1,2-O-isopropylidene-a-D-glucofuranose by way of acetylenic intermediates, Carbohydr. Res., 58 (1977) 89-108. 

As shown in Scheme 8.31, ketone 115 was further homologated to carbacyclic analogs of L-idose and D-glucose. As illustrated, temporary protection of the ketone through a thioacetal was followed by the removal of the benzoyl groups. Protection with acetonides, and cleavage of the thioacetal, afforded the ketone 116. This intermediate was transformed into carba-idopyranose by... 

While the aforementioned methodologies constitute the most useful and general synthetic procedures for the preparation of 1,6-anhydropyranoses, a number of alternative routes have been described [27]. As mentioned previously, solutions of a number of sugars in aqueous acid at equilibrium contain considerable amounts of 1,6-anhydro sugars. A simple synthesis of tri-0-acetyl-l,6-anhydro-/J-L-idopyranose has been reported by Stoffyn and Jeanloz that utilizes the acid-catalyzed dehydration of L-idose to form the anhydro ring [28]. 

Oxirans.- The acid-catalyzed hydrolysis of 5,6-anhydro-l,2-0-iso-propylidene-B-L-ldofuranose has been re-examined, because the conditions reported previously for the preparation of L-ldose were found not to give a pure product conditions for optimum production of L-idose, 1,2-0 -lsopropylidene-B-L-ldofuranose, or 1,6-anhydro-L-idopyranose were found.The 2,5 3, -dlanhydride (5) has been synthesized from 1,2-0-cyclohexylldene-a-D-xylofuranose via the dltosylate (6) (Scheme 1). Sulphonyloxy groups at C-3 in acetals such as (7) are reported to be readily displaced with the... 

Chapter 7 contains a reference to a synthesis of L-idose among many reactions resulting from photobromination of penta-0-benzoyl 3-l>glucopyranose, and the synthesis of pure anhydrous D- and L-gulose via boronate esters of sugar lactones is covered in Chapter 16 (Schemes 1 and 2). 

Per-C-deuteriated D-glucose has been synthesized using the sequence shown in Scheme 1. A simple synthesis of L-idose from (1) by sequential treatment with sodium borohydride, sodium methoxide, and acid has been reported. Also prepared were L-idose di(ethylthio)acetal and 1-deoxy-L-iditol. 

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