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. 2013 Dec 11;53(4):1087–1091. doi: 10.1002/anie.201308334

Scheme 1.

Scheme 1

a) 4-Toluoyl chloride, DMAP, pyridine, CH2Cl2, 88 %; b) TFA, Et3SiH, CH2Cl2, 93 %; c) 16, Tf2O, 2,4,6-tri-tert-butylpyrimidine, 60 %; d) 1. NaOMe, 2. H2, Pd(OH)2, AcOH/H2O/THF, 80 %; e) PMBCl, NaH, DMF,78 %, f) 1. H2O, NIS, acetone, 0 °C, 78 %, 2. DMSO, Ac2O; g) 1. NH3, Et2O, reflux; 2. DMSO, Ac2O, 3. HCO2H, NaBH3(CN), MeCN, 74 % over 4 steps; h) Lawesson’s reagent, pyridine, toluene, 99 %; i) H2NCH2CH(OMe)2; j) TsOH, toluene, H2O, 50 °C, 65 % over 2 steps; k) TfOH, NIS, CH2Cl2, 0 °C, 39 %; l) H2 (6 bar), Pd(OH)2, AcOH/EtOAc/MeOH/H2O, 58 %. DMAP=4-(N,N-dimethylamino)pyridine, DMF=N,N-dimethylformamide, DMSO=dimethylsulfoxide, NIS=N-iodosuccinimide, PMB=para-methoxybenzyl, TFA=trifluoroacetic acid, Tf=trifluoromethanesulfonyl, THF=tetrahydrofuran, Ts=4-toluenesulfonyl.