Notiz über eine praktische Synthese der 2‐Desoxy‐D‐ribose

Developing high affinity oligosaccharide inhibitors: conformational pre-organization paired with functional group modification

“…Separations were done using a C 18 semi-preparative reverse-phase column, with combinations of water and methanol as eluents. 1 H NMR spectra were recorded at 500 or 600 MHz and 13 [a] D values are given in units of 10 −1 deg cm 2 g −1 . Electro-spray mass spectrometry and microanalyses were performed by the analytical services of this department.…”

“…Installation of the chlorine atom at the 2-position of 1,5anhydro-3-O-benzoyl-4-O-benzyl-2,6-dideoxy-hex-1-enitol (7) 3 to afford the rhamno-configuration has previously been accomplished by chloromethoxylation, but suffers from poor selectivities, difficult purification and, consequently, low yield (30-35%). 3,11 A modification of the Igarashi et al protocol 12 led to highly diastereofacial cis-addition of chlorine gas to 9 in CCl 4 , followed by the Koenig-Knorr glycosylation of acetic acid 13 to afford 8 in 88% overall yield in a ratio of 4 : 1 rhamno : quinovo (6-deoxy-L-gluco) configurations (Scheme 1). It should be noted that the use of 1,2-propanediol cyclic carbonate as a solvent for the chlorination 12 leads to the opposite diastereofacial selectivity; a 6 : 1 mixture favoring the b-quinovosyl diastereomer of 8 in good yield.…”

“…The light yellow syrup was dissolved in CH 2 Cl 2 , washed with saturated NaHCO 3 and water, then dried with Na 2 SO 4 and evaporated to dryness. The product was purified by column chromatography (6 : 1 hexanes : ethyl acetate) to afford the target compound as a clear syrup (1.99 g, 88% overall yield; 3.9 : 1 distribution of a-rhamno-and b-quinovo-isomers): [a] 22 D +1.98 (c 1.0, CHCl 3 ); 1 H NMR (600 MHz, CDCl 3 ) d 8.09-7.19 (m, 10H, Ar-H), 6.19 (d, 1H, J = 2.0 Hz, H-1), 5.61 (dd, 1H, J = 3.8, 9.1 Hz, H-3), 4.62 (ABq, 2H, J = 11 Hz, PhCH 2 O-), 4.52 (dd, 1H, J = 2.0, 3.8 Hz, H-2), 3.99 (dq, 1H, J = 6.2, 9.5 Hz, H-5), 3.98 (dd ≈ t, 1H, J = 9.3 Hz, H-4), 2.14 (s, 3H, -C(O)CH 3 ), 1.37 (d, 3H, J = 6.2 Hz, H-6); 13 (m, 10 H, Ar-H), 5.53 (dd, 1H, J = 3.7, 9.2 Hz, H-3), 5.37 (s, 1H, H-1), 4.71 (dd, 1H, J = 1.2, 3.6 Hz, H-2), 4.69 (Abq, 2H, J = 10.9 Hz, PhCH 2 O-), 4.26 (dq, 1H, J = 6.3, 9.4 Hz, H-5), 3.80 (dd ≈ t, 1H, J = 9.3 Hz, H-4), 2.64 (m, 2H, SCH 2 CH 3 ), 1.37 (d, 3H, J = 6.3 Hz, H-6), 1.27 (t, 3H, SCH 2 CH 3 ); 13…”

“…[a] 22 D −1.91 (c 0.76, CHCl 3 ); 1 H NMR (600 MHz, CD 3 OD) d 7.54-7.23 (m, 5H, Ar-H), 5.41 (d, 1H, J = 1.2 Hz, H-1), 4.08-4.04 (m, 2H, H-2, H-5), 3.99 (dd, 1H, J gem = 11.2 Hz, J vic = 2.0 Hz, H-6 a ), 3.82 (dd, 1H, J gem = 11.2 Hz, J vic = 6.7 Hz, H-6 b ), 3.66 (dd, 1H, J = 2.8, 9.3 Hz, H-3), 3.63 (dd ≈ t, 1H, J = 9.3 Hz), 0.89 (s, 9H, -C(CH 3 ) 3 ), 0.07 (s, 3H, -Si(CH 3 ) a ), 0.05 (s, 3H, -Si(CH 3 ) b ); 13…”

Stereospecific synthesis of two epimeric 2-chlorodeoxy pentoses involving anomeric chlorine participation

“…The mixture of epimeric mono-chloro-pentoses was then obtained using methods described by Vargha and Kuszmann (7). The mixture of 1,2-dichloro derivatives was dissolved in carbon tetrachloride and refluxed with silver carbonate and water to remove the anomeric chlorine and the resultant mixture of acetates was deacetylated by refluxing them in 0.1 N hydrochloric acid.…”