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. Author manuscript; available in PMC: 2009 Jul 23.
Published in final edited form as: J Am Chem Soc. 2008 Jun 25;130(29):9268–9281. doi: 10.1021/ja801602q

Scheme III.

Scheme III

Conditions: (a) 3, 4-(methylenedioxy)phenylmagnesium bromide, THF/toluene (1:1 v/v), −78 to 23°C, 98% ; (b) 1M HCl, THF, 70°C; (c) trifluoromethanesulfonyl azide, CuSO4, K2CO3, H2O/MeOH, 0 to 23°C, 42% (2 steps); (d) 4-nitrobenzene-1-sulfonyl chloride, pyridine, cat. DMAP, DCM, 23°C, 55%; (e) cyclohexanamine, NMP, 80°C; (f) 2,4-difluorobenzoyl chloride, DIEA, DCM, 23°C, 65%; (g) H2, 5% Pd/C, MeOH, 23°C; (h) n-butylisocyanate, DIEA, DCM, 23°C, 28% (2 steps).