Triphenylphosphine → Di-tert-butyl bicarbamate

Participants

Reaction Steps

To a stirred solution of the product of step 2 (3.40 g, 6.42 mmol) and 2-(1-trityl-1H-imidazol-4-yl)-ethanol (2.73 g, 7.70 mmol) in methylene chloride (40 mL) was added triphenylphosphine (2.19 g, 8.35 mmol) followed by di-tert-butyl azodicarboxylate (1.77 g, 7.69 mmol). After 3 hours the reaction was concentrated and the residue partitioned between ethyl acetate and aqueous sodium bicarbonate solution. The organic layer was dried (sodium sulfate) and concentrated to yield an amber gum. Flash chromatography over silica (methylene chloride/methanol) afforded 5.42 g (97%) of partially purified product (contaminated with di-tert-butyl hydrazodiformate) as a pale yellow foam: 1H NMR (CDCl3) δ 7.81-7.74 (m, 1H), 7.64-7.55 (m, 1H), 7.53-7.44 (m, 2H), 7.41-7.03 (m, 31H), 6.69 (t, J=5.6, 1H), 6.53 (s, 1H), 4.48 (t, J=8.1, 1H), 4.08 (t, J=8.1, 1H), 3.84-3.58 (m, 4H), 3.44-3.34 (m, 1H), 2.91-3.80 (m, 1H), 2.78-2.68 (m, 1H), 2.63-2.51 (m, 1H) ppm.

Provenance & Evidence