Ribonic acid, 2-deoxy

The C33-C37-unit of (-F)-calyculin A (a marine natural product) is an amide derived from 5-0-methyl-4-deoxy-4-dimethylamino-D-ribonic acid, which has been prepared by Evans and... 

SCHEME 13.44 Synthesis of a 4-deoxy-4-dimethylamino-D-ribonic acid derivative. 

The C33-C37-unit of (-F)-calyculin A (a marine natural product) is an amide derived from 5-0-methyl-4-deoxy-4-dimethylamino-D-ribonic acid that has been prepared by Evans and co-workers [250]. A-Protection of sarcosine as benzyl carbamate affords acid 118 which is activated and used to iV-acylate the (5)-phenylalanine-derived oxazolidinone. This gives 119 that is methoxymethylated diastereoselectively (98 2) to give 120. Reductive removal of the chiral auxiliary, followed by Swem oxidation forms aldehyde 121 with little racemization if... 

N sodium hydroxide for 3 hr. at 25°, (52) could be isolated in a yield of 3.7%. The isolation procedure involved deionization and chromatography on a cellulose column. Except for characterization by elemental analysis and the preparation of the (2,4-dinitrophenyl)osazone (identical with that synthesized) and its triacetate, the proof of structure depended upon the identification of formic acid and 2-deoxy-n- ribonic acid, obtained after oxidation with hydrogen peroxide at pH 8. 

Coupling of the 4-amino-4-deoxy-ribonic acid derivative 54, obtained from L-serine aldehyde, and amine 55 furnished the amide 56, which underwent hydrolysis of the Boc protecting gronp followed by N-methylation to provide the oxazole 57 (Scheme 8)." ... 

The synthesis via Barton esters succeeded when the thiopirydyl adduct was created from 2,3 4,5-di-0-isporopylidene ribonic acid as a substrate [109c]. Treatment of this adduct with aqueous NaHCC>3 gave an epimeric mixture of ethyl 4,5 6,7-di-0-isopropylidene-3-deoxy-D-ara6/no- and D-r/6o-2-heptulosonates (3 1, respectively), the first one was further converted into DAH ethyl ester by use of Dowex (H+) resin in aqueous EtOH. 

Ribonic acid Lactone Anhydro Ribitol Deoxy... 

Amino-9-(2-deoxy- p-D-ribofuranosyl)adenine, A-153 9-(3-Amino-3-deoxy-p-D-ribofuranosyl)adenine, A-154 9-(2-Amino-2-deoxy- p-D-ribofuranosyl)guanine, A-277 9-(5-Amino-5-deoxy-p-D-ribofuranosyl)guanine, A-278 9-(2-Amino-2-deoxyribofuranosyl)-9i7-purin-6-amine, A-328 2-Amino-2-deoxy-D-ribonic acid, A-469... 

Amino-S-deoxy-D-xylono-l,5-lactam, T-177 2-Ammo-2,3,5-trideoxy-3-metliyl-L-arabinoiiic acid, A-427 2-Ammo-2,3,5-trideoxy-3-methyl-D-arabinonic acid, A-427 2-Ammo-2,3,5-trideoxy-3-methyl-D-lyxonic add, A-427 2-Amino-2,3,5-trideoxy-3-methyl-L-ribonic acid, A-427 2-Amino-2,3,5-trideoxy-3-methyl-D-xylonic acid, A-427... 

As pointed out above, aldonolactones/adds may isomerise at C-2 in the presence of strong base. No isomerisations were detected in the reaction of the 2,3-0-isopropylidene-protected lactones 3 and 5 with strong aqueous potassium hydroxide. Likewise, unprotected 5-bromo-5-deoxy-D-lyxono- and -D-ribono-lactones give rearrangements to L-ribonic and L-lyxonic acids, respectively [19]. In these cases isomerisation at C-2 was not observed either. It has thus been confirmed that aqueous base requires higher temperatures in order to epimerise at the carbon center a to the carboxylate group. 

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