Tetritols reduction

Reduction of the carbonyl group of an aldose (or of the oxo group in a ketose) gives the series of alditols (called tetritols, pentitols, hexitols, etc., with 4, 5,6,. .., carbon atoms). 

A difference in the behavior of methanesulfonic and p-toluenesul-fonic esters of 1,3-0-benzylidene-tetritols on reduction with lithium aluminum hydride in tetrahydrofuran has been described by Foster and coworkers 1,3-0 -benzylidene -2,4 - di - O - p - tolylsulfonyl - L -erythritol and -L-threitol gave the corresponding 4-deoxytetritol acetals, whereas l,3-0-benzylidene-2,4-di-0-(methylsulfonyl)-L-threitol was simply demethanesulfonylated to 1,3-O-benzylidene-L-threitol. 

Dihydro-6-(D-arahino-tetritol-l-yl)pteridine-2,4-dione 668 was unequivocally prepared by condensation of l-amino-l-deoxy-o-fructose (42) with 6-chloro-5-nitrouracil followed by concomitant reduction and cycliza-tion of 667 (62JCS44) (Scheme 172). 

Tetroses and Pentoses - 4-0- -Butyldimethylsilyl-2,3-0-isopropylidene-L-threose (1) has been prepared in seven efficient steps from o-xylose. 3,4-0-Isopropylidene-D-eythrulose (4) has been synthesized from the known tetritol derivative 2 by primary protection as the silyl ether 3, followed by Dess-Martin oxidation and desilylation. Compound 2 was derived from D-isoascorbic acid (see Vol. 22, p. 178, refs. 9,10). In a similar reaction sequence, the enantiomer 5 has been obtained from L-ascorbic acid. The dehomologation of several di-0-isopropylidenehexofuranoses e.g., 6- 7) has been carried out in two steps without intermediate purification, by successive treatment with periodic acid in ethyl acetate, followed by sodium borohydride in ethanol. Selective reduction of 3-deoxy-D-g/jcero-pentos-2-ulose (8) to 3-deoxy-D-g/> cero-pent-2-ose (9) has been achieved enzymically with aldose reductase and NADPH." 4-Isopropyl-2-oxazolin-5-one (10) is a masked formaldehyde equivalent that is easily converted to an anion and demasked by mild acid hydrolysis. One of the three examples of its use in the synthesis of monosaccharides is shown in Scheme 1. ... 

Addition of Grignard reagents to threose derivatives, in either cyclic or acyclic form, gave mainly the corresponding xylitol product (Scheme 5). Oxidation of these tetritol derivatives at C-1 followed by zinc borohydride reduction gave mainly lyxitol, whereas L-Selectride favoured the xylitol products these stereoselectivities were discussed. ... 

Scheme 4). The L-erythro-. D-erythro-. L-threo- and D-threo-isomers (6), present as a complex mixture of hemiacetals, were formed in a combined yield of 40-60% in the ratio 33 30 21 16. This was determined after reduction to the corresponding tetritols as mentioned in Chapter 18. ... 

Asymmetric aldolysation of glycolaldehyde has been achieved using the asymmetric acetal derivative (1) with triethylamine or calcium hydroxide the mixture of tetritol stereoisomers (2) obtained after borohydride reduction showed small stereoselectivities for... 

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