L-Mannopyranose

From L-arabinose, carba-sugars of the a-D-gluco and h-altro types were prepared from D-arabinose, carba-a-L-mannopyranose from D-ribose, that of the fi-L-manno modification from D-xylose, those of the -L-gluco and a-D-altro forms and, from D-glucose, those of the P-L-allo a-L-... 

Section III, 3,a. From 133, carba-a-L-mannopyranose pentaacetate (135) was produced as follows. 

Compound 138 was converted into carba- -L-mannopyranose pentaace-tate (139) in the usual way. - ... 

C6H1205 H20 6-Deoxy-a-L-mannopyranose monohydrate a-L-rhamnopyranose monohydrate (RHAMOH02)32... 

Quite analogous ring-closures occur when the 1-O-acetyl derivatives of the rhamnopyranose and talopyranose derivatives are treated with sodium azide in N,N-dimethylformamide. l-O-Acetyl-6-deoxy-2,3-0-isopropylidene-4-0-mesyl-a-L-mannopyranose is converted exclusively into l,4-anhydro-6-deoxy-2,3-0-isopropylidene-/3-L-talo-pyranose. In this instance, the azide nucleophile attacks the l-O-ace-tyl group, liberating an 0-1 oxide ion which reacts with inversion of C-4. The 4-epimeric, l-O-acetyl-6-deoxy-talose derivative gives 60% of the direct inversion product l,4-anhydro-6-deoxy-2,3-0-isopropyli-dene-a-L-mannopyranose, together with other products.50... 

By heating 32 in aqueous dimethyl sulfoxide (DMSO), containing sodium chloride, up to 170°C, loss of a methoxycarbonyl group and then -elimination of acetic acid occur to give alkene 33 in 70% yield. From this, carba-pl-L-mannopyranose 34 has been produced by conversion of the ester group to the hydroxymethyl function, hydroboration, and de-O-protection. Thus, the hydroboration step proceeded by cis-addition anti- to the allylic benzyloxy group. 

L-Mannopyranose (remember, the anomeric hydroxyl is down in the l series)... 

Takahashi, T. et al. A New Synthetic Approach to Pseudo-Sugars by Asymmetric Diels-Alder Reaction. Synthesis of Optically Pure Pseudo-f3-D-mannopyranose, I-Amino-I-deoxypseudo-a-D-manno-pyranose and Pseudo-a-L-mannopyranose Derivatives. 3.1 1990 [182]... 

The stmcture represents an a anomer because the anomeric -OH group and the -CH2OH group are trans. The compound is a-L-mannopyranose because the -OH group at C2 is the only non-anomeric axial hydroxyl group. 

As a Chiral Starting Material in L Amino Sugar and l-Nucleoside Synthesis. The recent improved synthetic access to the (45)-aldehyde has facilitated non-natural sugar and nucleoside synthesis. Asymmetric synthesis of several L-amino sugars has been reported. Julia olefination of the (45)-aldehyde with the sulfone afforded the key olefin intermediate as a 4 1E/Z mixture, which was elaborated via Sharpless asymmetric dihydroxylation (SAD) and protecting group interchange to afford the protected 2-deoxy-2-amino-L-mannopyranose (eq 4). ... 

The conformational depiction of jS-L-mannopyranose begins in the same way as that of jS-D-mannopyranose. L-Mannose is the mirror image of D-mannose. 

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