Reaktion #57093

Reaktionsgleichung

methanol

tert-butyl 4-[(3-bromophenyl)(1-hydroxycyclohexyl)acetyl]piperazine-1-carboxylate

borane

→

tert-butyl 4-[2-(3-bromophenyl)-2-(1-hydroxycyclohexyl)ethyl]piperazine-1-carboxylate

Ausbeute 98.2%

Lösungsmittel

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturafter which time the reaction was cooled in an ice bath
2. 2
   Einengenconcentrated
3. 3
   workup.DISSOLUTIONThe resulting viscous, colorless oil was re-dissolved in ethyl acetate (25 mL)
4. 4
   Waschenwashed with a saturated aqueous solution of sodium bicarbonate, water, brine
5. 5
   Trocknendried over sodium sulfate
6. 6
   Filtrationfiltered
7. 7
   Einengenconcentrated
8. 8
   Sonstigeto give a white solid, which
9. 9
   Sonstigewas purified via flash column chromatography (silica, gradient from 10% ethyl acetate/hexane to 20% ethyl acetate/hexane)

Vorschrift

A solution of tert-butyl 4-[(3-bromophenyl)(1-hydroxycyclohexyl)acetyl]piperazine-1-carboxylate (2.12 g, 4.40 mmol) in dry tetrahydrofuran (10 mL) under nitrogen was treated dropwise with a solution of borane (1.0 M in tetrahydrofuran, 13.2 mL, 13.2 mmol). The resulting solution was heated at 70° C. for 2 h, after which time the reaction was cooled in an ice bath, treated dropwise with methanol (15 mL) and concentrated. The resulting viscous, colorless oil was re-dissolved in ethyl acetate (25 mL), washed with a saturated aqueous solution of sodium bicarbonate, water, brine, dried over sodium sulfate, filtered, and concentrated to give a white solid, which was purified via flash column chromatography (silica, gradient from 10% ethyl acetate/hexane to 20% ethyl acetate/hexane) to yield 2.02 g (98%) tert-butyl 4-[2-(3-bromophenyl)-2-(1-hydroxycyclohexyl)ethyl]piperazine-1-carboxylate as a white powder. MS (ESI) m/z 467/469 ([M+H]+); HRMS: calcd for C23H35BrN2O3, 466.1831; found (ESI), 467.1899; Anal. Calcd for C23H35BrN2O3: C, 59.10; H, 7.55; N, 5.99. Found: C, 59.14; H, 7.72; N, 5.77.

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