(R)-1-methyl-3,3-diphenylhexahydropyrrolo[1,2-c][1,3,2]oxazaborole toluene → (S)-methyl 2-(2-(3-bromophenyl)-7-iodo-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)-2-hydroxyacetate

Participants

Reaction Conditions

Reaction Steps

To a stirred yellow solution of methyl 2-(2-(3-bromophenyl)-7-iodo-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)-2-oxoacetate (1.7 g, 3.40 mmol) in anhydrous toluene (100 mL) was added 1.1M (R)-1-methyl-3,3-diphenylhexahydropyrrolo[1,2-c][1,3,2]oxazaborole/toluene (1.236 mL, 1.360 mmol). The mixture was cooled to −35° C. and a solution of catechoborane/toluene (1.166 mL, 4.76 mmol) was added over 5 min. After 30 min, the reaction mixture was slowly warmed to −15° C. and stirred for additional 2 h. and diluted with EtOAc (600 mL) and sat. Na2CO3 (100 mL). The mixture was stirred vigorously for 30 min, and the organic phase washed with sat Na2CO3 (2×100 mL), dried (Na2SO4), filtered, concentrated and the residue was purified by silica gel chromatography (5-100% EtOAc/hexane) to afford desired (S)-methyl 2-(2-(3-bromophenyl)-7-iodo-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)-2-hydroxyacetate (1 g, 1.992 mmol, 58.6% yield) as off-white solid. 1H NMR (500 MHz, CDCl3) δ: 8.21 (t, J=1.7 Hz, 1H), 7.96 (dt, J=7.8, 1.2 Hz, 1H), 7.59-7.55 (m, 1H), 7.37 (t, J=7.8 Hz, 1H), 7.09 (s, 1H), 5.78 (s, 1H), 3.87 (s, 3H), 3.54 (br. s., 1H), 2.61 (s, 3H). LCMS (M+H)=504.05.

Provenance & Evidence