2,3 -O-Isopropylidene-L-threitol

A base-promoted reaction between L-threitol and tetraethylene glycol di-tosylate afforded (165) the chiral bis(15-ctown-5) derivative l-146 as well as the trans-fused bicyclic system l-147 containing 15-crown-5 and 17-crown-5 rings. These constitutional isomers, which were separated chromatographically, were characterized by preparing l-147 unequivocally by a stepwise route from 2,3-O-isopropylidene-L-threitol. 

Chow and coworkers 40,41 reported the synthesis and characterization of homochiral dendrimers through the first generation by using (2R, 3i )-tartaric acid as the chiral building block. The mode of preparation is based on three parts the three-directional core, 1,3,5-trihydroxybenzene (61), the chiral connector, l-0-tosyl-4-terf-butyl-phenoxy-2,3-O-isopropylidene-L-threitol (62), and a branching unit, l-benzyloxy-3,5-dihydroxyben-zene (63). 

Scheme 1.24. Regioselective addition to Cgo of a 2,3-O-isopropylidene-L-threitol-tethered bis-azide under formation of diaza-bishomo-[60]fullerene 252, and regioselective interconversion between the azahomo- (252) and the epiminofullerene (254) isomers.

A. L-Threitol 1,4-bismethanesulfonate. A dry, 1-L, round-bottomed flask equipped with a magnetic stirring bar, vacuum adapter, rubber septum, and a nitrogen line (Note 1) is charged with 2,3-O-isopropylidene-L-threitol (25.0 g, 0.154 mol) (Note 2), pumped under high vacuum for 10 min, and a nitrogen atmosphere is introduced. 

The submitters used 2,3-O-isopropylidene-L-threito prepared according to the procedure in Org. Synth., Coll. Vol. VII11993, 155-161. The diol was recrystallized from 1 1 hexanes-diethyl ether prior to use. Alternatively, 2,3-O-isopropylidene-L-threitol can be purchased from Aldrich Chemical Company, Inc. 

The tosylate groups of 47 readily undergo double nucleophilic displacement with a variety of nucleophiles. Reaction of 47 with sodium iodide in acetone provides (2 5,35)-1,4-diiodo-2,3-O-isopropylidene-L-threitol (70) [24]. This is converted in two steps to ( S)-4-hydroxy-2-... 

The diversity associated with silyl protecting groups as well as the chemical conditions available for their removal makes them attractive alternatives to benzyl protection of the hydroxy groups of either D- or L-tartaric acid derivatives. O-isopropylidene-L-threitol (37) is mono-protected with er -butyldimethylsilyl chloride to furnish 266, which is converted in three steps to the nitrile 267. Reduction with DIBAL and Wittig olefination followed by desilylation with fluoride and Swern oxidation of the resulting alcohol provides aldehyde 268, which reacts with methyl 10-(triphenylphosphorane)-9-oxo-decanoate (269) to afford enone 270. Reduction of 270 with subsequent preparative TLC and acetal hydrolysis furnishes (9R)-271 and (9 S)-272, both interesting unsaturated trihydroxy Cig fatty acid metabolites isolated from vegetables [91] (Scheme 62). 

Convergent construction (Scheme 7.14) began with the treatment of (25, 35)-(-)-l,4-di-O-tosyl-2,3-0-isopropylidene-L-threitol with one half equivalent of 4-fert-butylphenol under basic conditions to yield the mono-O-arylation product (62). Subsequent reaction of the chiral aryl ether 62 with one-half equivalent of dihydroxybenzene 42 63, followed by hydrogenolysis with palladium on charcoal gave the dendron 64. Attempted preparation of the disubstituted phenol 64 via reaction of the tosylate 62 with one third equivalent core 61 resulted in low yields (ca. 26 %). Poor solubility of the tris-phenolic trianion was suggested as a rationale for the low conversion. 

Varying the ratio between Ti(0-iPr)4 and the diethyl tartrate auxiliary using EtOAc as solvent from 1 1 to 1 4 did not have any impact on the ee value, but the kinetics of the reaction changed tremendously. This means that in the former case (at 20 °C) only 2.5% of the starting prochiral sulfide remains after 140 min, whereas in the latter this figure is 24.5%. Furthermore, comparing different chiral diols (e.g., other tartrates, (S)-l,2,4-butanetriol, 2,3-O-isopropylidene-D-threitol) actually showed that a range of structurally rather dissimilar auxiliaries could also be used. Because of market availability and other process-dependent considerations diethyl tartrate was finally chosen for the current application. 

Benzyl-1,2-0-isopropylidene-5-thio-p-L-arabinopyranoside, T-58 1-0 -Benzyl-2,3-O -isopropylidene-D-threitol, T-100... 

From poly(2,3-0-isopropylidene- 1,4-di-O-methacryloyl-L-threitol) (aibn, toluene, 60°C)... 

Fuganti and co-workers used 2R 3R-tartaric acid for the synthesis of 3-benzamido-2,3,6-trideoxy-L-xy/o-hexose (393). The acid was converted according to a known procedure into 2,3-0-isopropylidene-4-0-p-toluenesulfonyl-L-threitol (388). Reduction of 388 with lithium aluminum hydride gave 4-deoxy-... 

A method for the electrochemical reduction of D-xylose to 2-deoxy-D-r/rr o-pentitol has been described. The homogeneous hydrogenation of sugars using tris-triphenylphosphine ruthenium chloride is improved in the presence of hydrogen chloride, which inhibits competitive decarbonylation of the sugar. L-(2,3)-Threitol is easily prepared from ( + )tartaric acid by lithium aluminium hydride reduction of the 2,3-0-isopropylidene derivative of diethyl tartrate, followed by acid hydrolysis of the resultant ketal. ... 

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