Toluene-p-sulphonic anhydride → HCID 12849000, compound

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Reaction Steps

p-toluenesulfonic anhydride (520 mg, 1.59 mmol) and N,N-diisopropylethylamine (300 μl, 1.72 mmol) are added to an ice-cold, stirring solution of p-nitrobenzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (484 mg, 1.59 mmol) in anhydrous methylene chloride (17 ml). The resulting solution is stirred in the cold for 2 hours, then diluted with more methylene chloride, washed with water, 1μ ph 3.4 phosphate buffer and saturated aqueous sodium bicarbonate, dried with magnesium sulfate, filtered, and evaporated under vacuum. Addition of cold ethyl acetate and a few seeds crystals to the oily residue induces crystallization. The product is collected, washed with cold ethyl acetate, and dried under vacuum to afford p-nitrobenzyl 3-(p-toluenesulfonyloxy)-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylate (446 mg, 61%) as off-white crystals: mp 99°-102° (dec.); IR (neat) 1790, 1725, 1521, 1345, and 1172 cm-1 ; UV (CH2Cl2) 272 nm; NMR (CDCl3) δ 2.40 (s, 3, ArCH3), 3.06 (dd, 1, J=3.0 and 17.2, H6β), 3.16 (dd, 1, J=9.0 and 9.0, H4a), 3.31 (dd, 1, J=9.0 and 10.0, H4b), 3.59 (dd, 1, J=5.8 and 17.2, H6α), 4.24 (m, 1, H5), 5.20 and 5.32 (ABq, 2, J=14.0, CH2Ar), 7.32 and 7.77 (two d's, 4, J=8.0, p-MeC6H4), 7.51 and 8.19 (two d's, 4, J=8.0, p-NO2C6H4).

Provenance & Evidence