Boron tribromide → (1R,10R,11S,16S)-5-hydroxy-N,1,11,15,15-pentamethyl-8-thiatetracyclo-[8.8.0.02,7.011,16]octadeca-2,4,6-triene-3-carboxamide

Participants

Reaction Conditions

Reaction Steps

A solution of (1R,10R,11S,16S)-5-methoxy-N,1,11,15,15-pentamethyl-8-thiatetracyclo[8.8.0.02,7.011,16]octadeca-2,4,6-triene-3-carboxamide (75) (0.17 g, 0.42 mmol) in anhydrous CH2Cl2 (5.0 mL) was cooled with an ice bath under N2. To the mixture BBr3 (1 M in CH2Cl2, 1.6 mL, 1.6 mmol) was added dropwise. The mixture was stirred at 0° C. for 2.5 h then at room temperature for 3.25 h. The solution was cooled to 0° C. and quenched with anhydrous MeOH. The solution was evaporated and the residue co-evaporated with anhydrous MeOH. The solid was suspended in EtOAc and washed with 0.09 M HCl (11 mL). The mixture was taken to pH=7.5 using sodium bicarbonate. The organic layer was separated was concentrated to dryness. The crude material was triturated with MeOH then filtered and washed with MeOH to yield (1R,10R,11S,16S)-5-hydroxy-N,1,11,15,15-pentamethyl-8-thiatetracyclo-[8.8.0.02,7.011,16]octadeca-2,4,6-triene-3-carboxamide (76) (0.09 g, 57%) as a white solid. 1H NMR (DMSO-d6): δ 9.37 (s, 1H), 8.10 (m, 1H), 6.36 (d, 1H), 6.18 (d, 1H), 2.94 (dd, 1H), 2.80 (d, 1H), 2.65 (d, 3H), 1.81 (d, 1H), 1.62-1.26 (m, 12H), 1.09 (ddd, 1H), 0.87-0.81 (m, 7H), 0.78 (s, 3H). MS m/z 388 (C23H33NO2S+H+).

Provenance & Evidence