4-Boc-1-Cbz-piperazine-2-carbaldehyde → 1-Benzyl 4-tert-butyl 2-vinylpiperazine-1,4-dicarboxylate

n-Butyl lithium (2.5M solution in hexane, 4.0 mL, 10 mmol) was added to a suspension of methyltriphenylphosphonium bromide (4.19 g, 11.7 mmol) in THF (100 mL) at −78° C. After 10 min., the reaction mixture was allowed to warm to rt. After 1 h, the reaction mixture was cooled to −78° C., and a solution of 1-benzyl 4-tert-butyl 2-formylpiperazine-1,4-dicarboxylate (3.07 g, 8.81 mmol) in THF (10 mL) was added dropwise. After 2 h, the reaction mixture was allowed to warm to rt and was quenched with NH4Cl (saturated, aqueous solution). The reaction mixture was diluted with water (100 mL) and was extracted with EtOAc (3×150 mL). The combined organics were dried over Na2SO4, filtered, and concentrated under reduced pressure. Purification by column chromatography (0 to 20% EtOAc in Hexane gradient) gave 2.33 g (76%) of the desired product as a thick oil. Rf=0.35 in 30% EtOAc/Hexane. LC-MS: RT=10.1 min., [M+H]+=369.1.

1. waitAfter 1 h
2. temperaturethe reaction mixture was cooled to −78° C.
3. waitAfter 2 h
4. temperatureto warm to rt
5. customwas quenched with NH4Cl (saturated, aqueous solution)
6. additionThe reaction mixture was diluted with water (100 mL)
7. extractionwas extracted with EtOAc (3×150 mL)
8. dry with materialThe combined organics were dried over Na2SO4
9. filtrationfiltered
10. concentrationconcentrated under reduced pressure
11. customPurification by column chromatography (0 to 20% EtOAc in Hexane gradient)

ORD record

ord-411c533f6e9e459a9d6bab26ded5d9d6

Source dataset

uspto-grants-2011_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07943622B2