2-O-benzyl 1-O-tert-butyl (2R,4R)-4-hydroxypyrrolidine-1,2-dicarboxylate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The alcohol 34 (5.34 g, 16.7 mmol) and CBr4 (16.6 g, 50 mmol) were dissolved in 100 mL dichloromethane and solid triphenylphosphine (13.1 g, 50 mmol) was added over a 10 min period. This solution was allowed to stir for 18 h then worked up and purified as for the synthesis of 4a. This gave 4.73 g (74% yield) of the title compound. This material crystallized on standing to give material of m.p.=87°-88° C. (Et2O/hexane). 1H NMR (CDCl3) δ 1.35/1.46 (2s, 9H), 2.41 (m, 1H), 2.58 (m, 1H), 3.90 (m, 2H), 4.48 (m, 2H), 5.19 (m, 2H), 7.34 (s, 5H). purified as for the synthesis of 4a

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The alcohol 34 (5.34 g, 16.7 mmol) and CBr4 (16.6 g, 50 mmol) were dissolved in 100 mL dichloromethane and solid triphenylphosphine (13.1 g, 50 mmol) was added over a 10 min period. This solution was allowed to stir for 18 h then worked up and purified as for the synthesis of 4a. This gave 4.73 g (74% yield) of the title compound. This material crystallized on standing to give material of m.p.=87°-88° C. (Et2O/hexane). 1H NMR (CDCl3) δ 1.35/1.46 (2s, 9H), 2.41 (m, 1H), 2.58 (m, 1H), 3.90 (m, 2H), 4.48 (m, 2H), 5.19 (m, 2H), 7.34 (s, 5H). purified as for the synthesis of 4a