5.6- Dideoxy-5- -£-idopyranose

CjoH NOuP CH3OH 1, 2,3,4-Tetra-0-acetyl-5,6-dideoxy-6-C-nitro-5-C-(phenylphosphinyl)-/ -L-idopyranose, methanolate (IDPYRS)105... 

No formation of 1,6-anhydride is observable in the acid-catalyzed equilibrium mixture from 5,6-bis(acetamido)-5,6-dideoxy-L-idofura-nose. The compound exists only in the furanose form, no 5-acet-amidopyranose or its 1,6-anhydride being chromatographically detectable. Apparently, in this case, the nucleophilicity of the acetamido group is too low for a 1,6-anhydride ring-closure, for the stereochemistry corresponds completely to 176a. 5,6-Bis(acetamido-l,6-anhydro-5,6-dideoxy-j8-L-idopyranose is obtainable, in another way, by acetylation of 5,6-diamino-l,6-anhydro-5,6-dideoxy-/3-L-idopyranose (65) (see Section 11,2 p. 137). It is not a true equilibrium partner of 5,6-bis(acetamido)-5,6-dideoxy-L-idofuranose. 

This difference in the AG values is especially observable in the temperature-dependent, nuclear magnetic resonance spectrum of 5,6-bis(acetamido)-l,6-anhydro-5,6-dideoxy-j8-L-idopyranose. This sugar contains a flve-membered and a six-membered ring amide in... 

Fig. 6.—Nuclear Magnetic Resonance Signals for the Anomeric Protons of 5,6-Bis(acetamido)-l,6-anhydro-5,6-dideoxy-/8-L-idopyranose at Various Temperatures.

Adley and Owen [3] described the synthesis of 5-thio-L-idopyranose 12 by the ring opening of 5,6-dideoxy-5,6-epithio-l,2-0-isopropyhdene-a-L-idofuranose 13, with potassium acetate in a mixture of glacial acetic acid and acetic anhydride and subsequent deprotection. 5-Thio-D-glucopyranose 10 was first synthesized by Feather and Whistler [8]. 

Methyl 2-acetamido-5,6-anhydro-2-deoxy-0 -L-idofuranoside (33) has been synthesized from 2-acetamido-2-deoxy-D-glucose and has been employed in the preparation of 2-acetamido-5-amino-2,5-dideoxy-D-glucopyranose as the sulphur dioxide adduct (34) (Scheme 7). Similarly the corresponding idopyranose was prepared in an analogous manner. ... 

Pseudo-a-L-idopyranose. 1,6-Dideoxy-I-(hydroxymethyl)-L-chiro-inositol, 9CI. 

Pseudo-cc-DL-idopyranose. 1,6-Dideoxy-l-(hydroxymethyl)-DL-chko-inositol, 9CI [74560-71-7]... 

Acetamido-5-amino-2,5-dideoxy-L-idopyranose, D-441 2-Acetamido-4-C-(3-amino-2,2-dihydroxy-3-oxopropyl)-2,6-dideoxy-galactopyranose, S-33... 

Acetamido-3,4-di-0-acetyI-5-deoxy-p-D-ribopyranose, A-332 5-Acetamido-5,6-dideoxy-l,2-0-isopropylidene-p-L-talofuranose, A-418 5-Acetamido-5,6-dideoxy-L-taIofuranose, A-418 5-Acetamido-1,2.3,4-tetra-0-acetyI-5-deoxy-a-D-lyxopyranose, A-299 2-Acetamido-1,3,4,5-tetra-0-acetyI-2,6-dideoxy-D-altritol, A-367 5-Acetamido-2,3,4-tri-0-acetyI-l,6-anhydro-5-deoxy-p-L-idopyranose, A-293... 

It is clear that carbohydrates are multifunctional compounds because they contain hydroxyl units, aldehyde or ketone units, and sometimes carboxyl units. Carbohydrates may also contain an amine unit to give amino sugars. Examples are 2-amino-2-deoxy-P-d-mannopyranose (d-mannosamine, 103), 3-amino-3,6-dideoxy-P-d-glucopyranose (104), and 3-deoxy-P-d-idopyranose (105). These compounds are known as deoxy sugars because they have an OH unit replaced with NHg or H, or another group. 

A racemic synthesis of 3,4-dideoxy-2- -methyl-4-phenylphosphinyl-D. L-alvcero-tetrafuranose has been reported as has the preparation of the four epimers of 5-deoxy-3-Q-methyl-5-C-[(R)-and (S)-phenylphosphinothioyl]-Q- and j8-D-xylopyranoses (see SPR Vol 21, p 167). The preparation of 5-deoxy-5-[(RS)-ethylphosphlnyl]-a,/8-L-idopyranoses has been described,and 1,2,4,6-tetra-Q-acetyl-5-deoxy-3-Q-methyl-5-[(RS)-phenylphosphinyl and methyl phosphinoyl] a,j9-L-idopyranoses have been prepared. ... 

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