2.3.4.5- tetra-O-acetyl

Ci3H1809 1,2,3,4-Tetra-O-acetyl-a-D-arabinopyranose (TARABP)318 C13H1809 1,2,3,4-Tetra-0-acetyl-/ -D-arabinopyranose (TACARP01)318 C15H20O12 Methyl 1,2,3,5-tetra-0-acetyl-/ -D-galactofuranuronate... 

C20H24NOUPCH3OH 1,2,3,4-Tetra-O-acetyl-5,6-dideoxy-6-C-nitro-5-C-(phenyl-phosphinyl)-yS-L-idopyranose, methanolate IDPYRS 43 253... 

A much more systematic approach involves the use of p-chlorides carrying non-participating groups at C-2 as is exemplified by the Wolfrom synthesis of p-isomaltose octa-acetate from 1,2,3,4-tetra-O-acetyl-p-D-glucopyranose and 3,4,6-tri-0-acetyl-2-0-nitro-p-D-glucopyranosyl chloride In this work silver carbonate was used as acid acceptor and soluble silver perchlorate was fmmd to exert valuable catalytic influence, but later the perchlorate itself was used in an application to a tiisacchar-ide s mthesis which incorporated the trityl ether modification 2 ). 

Likewise, 5-C-(butylphosphinyl)-5-deoxy-D-xylopyranose 33 was obtained34 from 25 (R = Ac or Bz) by way of the phosphine oxide intermediate 28 (R = Bu). An acetyl derivative having structure 38, namely, 1,2,3,4-tetra-O- acetyl- 5-C- [(R)- butylphosphinyl]-5- deoxy- a -D-xylo-pyranose,33 crystallized from the diastereomeric mixture of the per-O-acetylated products from 33. 

The melt polymerizations of 1,2,3,4-tetra-0-acetyl-j3-D-mannose and -D-galactose in the presence of zinc chloride have been described.152 Chemical investigation of the structure of the polymannose suggested that it is mainly an a-D-( 1—+6)-linked polymer having a Pm of 10. In the same way, 1,2,3,4-tetra-O-acetyl-n-gaIactose was polymerized. 

Lamberth and co-workers [23] synthesized several chiral mandelamides in a Passerini reaction of 1,2,3,4-tetra-O-acetyl-a-D-galacturonic acid with achiral benzal-dehydes and isocyanides (Scheme 9.15). 

Another route involves the isomerization at C-5 of the corresponding D-glucuronic derivative via the C-bromide 56. Compound 56 was obtained by treatment of 1,2,3,4-tetra-O-acetyl-a-D-glucopyranuronate (58) with A-bromosuccinimide. Reduction of 56 with tributyltin hydride affords the a-L-idopyranuronate derivative 57 together with the glucopyranuronate 58 ( 20%), which could be separated and converted back into the bromide.172... 

It is of interest to contrast the above-described mechanism (for the alkali-catalyzed transformation of phenyl /S-D-glu copyranoside to 1,6-anhydro-jS-D-glucopyranose) to the mechanism proposed by Lemieux and Brice38 for the acid-catalyzed transformation of 1,2,3,4-tetra-O-acetyl-jS-D-glucose (XXXI) to tri-0-acetyl-l,6-anhyd ro-/S-D-glu copy ran ose (XXXIII). Evidence was obtained showing that, in the presence of stan-... 

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