Diastereoselective Synthesis of Galactopyranosyl Amino Esters and Their Transformation into C‐Nucleosides.

Abstract

Diastereoselective Synthesis of Galactopyranosyl Amino Esters and Their Transformation into C-Nucleosides. -Galactopyranosylated olefinic esters of type (III) yield the corresponding amino esters (V) and (VI) on treatment with amines. Amino esters (V) give ureido amino esters (VIII) when reacted with isocyanates. Cyclization of (VIII) affords the corresponding dihydropyrimidine-2,4-diones of type (IX). -(KATIYAR, D.; MISHRA, R. C.; TRIPATHI*, R. P.; J. Carbohydr. Chem. 23 (2004) 1, 49-70; Div. Med. Chem., Cent. Drug Res. Inst., Lucknow 226 001, India; Eng.) -M. Bohle

Spirocyclic Nucleosides in Medicinal Chemistry: An Overview

“…Larger amount of these compounds were successfully prepared via an efficient and versatile method for introducing dihydropyrimidinone skeleton on protected glucofuranose derivative by reacting glycosyl ureas with DBU as catalyst and TBAB as co-catalyst in 4A 0 MS [116][117][118].…”

Diastereoselective Synthesis and Antifungal Activity of Glycosyl Isoxazolines

“…It is interesting to note that the reaction of crotonic acid with 3a gave regioisomeric glycosyl isoxazoline (15) with 4-carboxy and 5-methyl substituents as distereoisomeric mixture. It is speculated that due to the electron-withdrawing effect of COOH, the polarization is in such a manner that electron density is more at b carbon to carboxyl group, which results in compound 15.…”

“…As changing the substituent in the sugar ring did not improve the diastereoselection, we were curious to compare the diastereoselectivity of furanose and pyranose skeletons at least with three alkenes, ethyl acrylate, allyl alcohol, and 2-allyl phenol. Thus, galactopyranosyl oxime (4), obtained from the galactopyranosyl ulose (2) [15] and hydroxylamine hydrochloride, on treatment with N-chlorosuccinimide resulted in the unisolated galactopyranosyl hydroxamoyl chloride, which on addition of DBU gave glycosyl nitrile oxide and the latter on in situ reaction with ethyl acrylate gave a diastereoisomeric mixture of galactopyranosyl isoxazolines (26) in 65% yield. The structure of 26 was elucidated on the basis of IR, NMR, and MS spectral data.…”

“…Calcd for C 12 H 19 NO 6 : C, 52.74; H, 7.01; N, 5.13. Found: C, 52.96; H, 7.32; N, 5.01.5(R,S)-Carboxy-3-[(1 0 R,2 0 R,3 0 S,4 0 R)-1 0 ,2 0 -O-isopropylidene-3 0 -O-methyltetrahydrofuranos-4 0 -yl]-2-isoxazoline(15).Colorless oil, Rf 0.40 (hexane:ethyl acetate, 1:1); [a] D 25 -418 (c 0.4, CHCl 3 ), MS (FAB) ¼ m/z 302 (M þ H) þ ; IR (Neat): n max cm 21 3352, 2937, 2362, 1769, 1709, 1658, 1622, 1447, 1378; 1 H NMR (CDCl 3 , 200 MHz): d 9.76 (bs, exchangeable with D 2 O, 1H, -COOH), 7.22 (m, 1H, H-4), 5.99, 5.91 (d, J ¼ 3.6 Hz, 1H, diastereomeric H-1 0 ), 4.84 (d, J ¼ 3.3 Hz, 1H, H-4 0 ), 4.59 (d, J ¼ 3.6 Hz, 1H, H-2 0 ), 4.13 (d, J ¼ 3.3 Hz, 1H, H-3 0 ), 3.43 (s, 3H, -OCH 3 ), 1.95 (d, J ¼ 6.9 Hz, 3H, CH 3 ), 1.81 (m, 1H, H-5) 1.49 and 1.33 [s, H, C(CH 3 ) 2 ]. 13 C NMR (CDCl 3 ): d 164.4 (C ¼ O), 163.8 (C5 5N); 149.R,S)-Carbethoxy-3-[(1 0 R,2 0 R,3 0 S,4 0 R)-3 0 -O-benzyl-1 0 ,2 0 -O-isopropylidenetetrahydrofuranos-4 0 -yl]-2-isoxazoline (16).…”