A new stereoselective preparation of N-aceyl-D-galactosamine (1b) starting from the known p-methoxyphenyl 3,4-O-isopropylidene-6-O-(1-methoxy-1-methylethyl)-beta-D-galactopyranoside (10) is described using a simple strategy based on (a) epimerization at C-2 of 10 via oxidation-reduction to give the talo derivative 11, (b) amination with configurational inversion at C-2 of 11 via a S(N)2-type re...

The molecules of methyl 3-(2-nitrophenylhydrazono)butanoate, C(11)H(13)N(3)O(4), (I), and methyl 3-(2,4-dinitrophenylhydrazono)butanoate, C(11)H(12)N(4)O(6), (II), both prepared from methyl 3-oxobutanoate and the corresponding nitrophenylhydrazine, exhibit polarized molecular electronic structures; in each of (I) and (II), the molecules are linked into chains by a single C-H...O hydrogen bond. ...

quercetin, a ubiquitous flavonol, represents a promising leading drug for development of new chemotherapeutic agents. however, its limited cytotoxicity to cancer cells hampers its clinical use. in order to obtain novel quercetin derivatives with superior cytotoxicity, seven alkylated quercetin derivatives were synthesized. solubility of these derivatives was determined by turbidimetry. cytotoxi...

Sir: As part of our effort aimed at the synthesis of new rifamycin derivatives,1) the 3-hydrazino derivatives of rifamycin S (2) and SV (3) have been obtained by treating 3-bromorifamycin S (1a) with isopropylidene-methyl hydrazine and with isopropylidene-methyl hydrazine followed by hydrazine, respectively.2) We wish to describe here a novel rearrangement of the ansa bridge under acidic condit...

The synthesis of compounds 6-8, derived from 2,3:5,6-bis-O-isopropylidene-D-mannofuranose (3), and the preparation of products 16 and 17, obtained from 2,3-O-isopropylidene-D-ribose (13) is reported. The first free radical cyclization of enantiomerically pure alkyne-tethered oxime ethers derived from carbohydrates (6, 8, 16, and 17) is described. These radical precursors have been submitted to ...