Tin tetrachloride → Benzamide

Participants

Reaction Steps

To a suspension of N-benzoylcytosine (29.11 g, 135.40 mmol) in 250 mL of distilled CICH2CH2Cl was added 66.80 ml (270.82 mmol) of BSA. This suspension was heated to a gentle reflux for 40 min during which time a clear solution was effected. At this time, the solution was cooled to room temperature and 20 g (45.15 mmol) of 2-deoxy-2-[(trifluoro-acetyl)amino]-β-D-glucopyranose-1,3,4,6-tetraacetate was add followed by a solution of 100 mL of CICH2CH2Cl containing freshly distilled SnCl4 (15.17 mL, 135.42 mmol). This resulting slightly yellow solution was refluxed for 2 h. At this time, the reaction was cooled to room temperature and 57 g of NaHCO3 was added and stirred before the addition of 22 mL of H2O. The mixture was stirred for an additional 20 min at room temperature. The suspension was filtered and washed through a pad of celite with CHCl3. The filtrate was washed with saturated, aqueous NaHCO3 and brine. The organic layer was further treated with charcoal before filtration through a pad of celite. The filtrate was dried over Na2SO4, filtered and concentrated in vacuo to a yellowish foam. This residue was chromatographed on silica gel eluted with CH2Cl2 and 1 to 3.5% CH3OH/CH2Cl2. The product was further purified by recrystallization from CH3OH/H2O. As a single crop of white crystals the desired glycosylation product, N- [1,2-dihydro-2-oxo- 1-[3,4,6-tri-O-acetyl-2-deoxy-2-[(trifluoroacetyl)amino]-β-D-glucopyranosyl]]-4-pyrimidinyl]benzamide was obtained (9.22 g, 34%). 1H NMR: (CDCl3): δ anomeric H-1 6.21 (d, 1H), acetyl ester 2.06 (s, 3H), acetyl ester 1.82 (s, 3H). FAB-MS: m/z 599 for (M+1)+, 1197 for (2M+1)+. Microanalysis: calculated for C25H25N4 O10C 50.17, H 4.21, N 9.36; found: C 50.01, H 4.00, N 9.16.

Provenance & Evidence