Carbon tetrabromide → tert-Butyl [(2R)-4,4-dibromobut-3-en-2-yl]carbamate

HRID 2066907Notes

Reaction equation

C1C=CC(P(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1.[C:20]([Br:24])(Br)(Br)[Br:21].O=[CH:26][C@H:27]([NH:29][C:30](=[O:36])[O:31][C:32]([CH3:35])([CH3:34])[CH3:33])[CH3:28]>C(Cl)Cl.[Zn]>[Br:21][C:20]([Br:24])=[CH:28][C@H:27]([NH:29][C:30](=[O:36])[O:31][C:32]([CH3:33])([CH3:35])[CH3:34])[CH3:26]

Participants

Conditions

Temperature: 0 °C

Procedure

A solution of zinc (135 g, 2.08 mol), PPh3 (545 g, 2.08 mol) and CBr4 (682 g, 4.08 mol) in CH2Cl2 (2 L) was stirred at 0° C. for 1.5 hr. A solution of (R)-tert-butyl 1-oxopropan-2-ylcarbamate (114 g, 0.66 mol) in DCM was added in one portion, and the reaction mixture was stirred at 0° C. for another 3 hr. The mixture was quickly passed though a silica gel, and the solvent was evaporated to give the crude (R)-tert-butyl 4,4-dibromobut-3-en-2-ylcarbamate. To a cooled (−78° C.) solution of the crude compound (R)-tert-butyl 4,4-dibromobut-3-en-2-ylcarbamate in THF (2 L) was added dropwise 2.5 M BuLi (0.75 L, 1.88 mol) under nitrogen. The reaction was quenched with water and the organic layer was separated. The aqueous layer was extracted with ethyl acetate. The organic layers were combined, washed with water, dried over MgSO4, filtered and concentrated to give the crude compound N.2, (R)-tert-butyl but-3-yn-2-ylcarbamate, which was used without further purification. 1H NMR (CDCl3) δ 4.47 (br s, 1H), 2.24 (s, 1H), 1.49 (s, 9H), 1.27 (s, 3H).

Workup

customthe solvent was evaporated

Sources & evidence

ORD record: ord-97d5257f4c59403a8b6c998c09028272
Source dataset: uspto-grants-2012_10
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08293752B2

Reaction notes

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