An expeditious convergent synthesis of a dibromotyrosine alkaloid inhibitor of mycothiol-S-conjugate amidase

Total Synthesis of Enisorine D and its Analogues

“…afforded enisorine D (4) in 90% yield. The structure was confirmed by 1 H NMR, 13 C NMR and IR spectroscopy and HRMS, and by comparing the NMR spectra with those of the isolated sample. Acid 13 was prepared from 2-(4-methoxyphenyl)acetic acid by demethylation using BBr 3 /CH 2 Cl 2 .…”

“…Tribromide 7 was then prepared in good yield from amide 8 by alkylation with 1,3-dibromopropane in the presence of K 2 CO 3 /DMF. 13…”

“…Compound 11 was prepared from 7 via a methylation reaction by using NaH/MeI/DMF, 14 where we observed rotamers in the 1 H and 13 C NMR spectra. The presence of rotamers in the 1 H and 13 C NMR spectra is the result of restricted rotation of the secondary amide bond. The observation of rotamers at this stage also further corroborates the fact that exclusive O-alkylation had occurred (not N-alkylation) in the conversion of amide 8 into tribromide 7.…”

“…15 Conversion of azide 12 into amine 6 was accomplished in an excellent 91% yield by using PPh 3 /THF/H 2 O. 16 The reaction between amine 6 and 2-(4-hydroxyphenyl)acetic acid (13) under standard acidamine coupling reaction conditions (EDC•HCl/HOBt/CH 2 Cl 2 ) 17…”

“…Infrared (IR) spectra were recorded as neat solids or liquids using a Bruker Alpha-p ATR FT-IR spectrophotometer. 1 H NMR (400 MHz) and 13 C NMR (100 MHz) spectra were recorded at ambient temperature using a Bruker Avance III 400 MHz spectrometer. The NMR samples were prepared by dissolving the products in CDCl 3 or DMSO-d 6 and TMS was used as an internal standard.…”