trans-1,4-Dibromo-2-butene → (4-Bromo-but-2-enyl)-(2,3-dihydro-benzo[1,4]dioxin-6-yl)-carbamic acid benzyl ester

HRID 1640526Notes

Reaction equation

[CH2:1]([O:8][C:9](=[O:21])[NH:10][C:11]1[CH:20]=[CH:19][C:14]2[O:15][CH2:16][CH2:17][O:18][C:13]=2[CH:12]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[Li]CCCC.[Br:27][CH2:28]/[CH:29]=[CH:30]/[CH2:31]Br>C1COCC1>[CH2:1]([O:8][C:9](=[O:21])[N:10]([CH2:31][CH:30]=[CH:29][CH2:28][Br:27])[C:11]1[CH:20]=[CH:19][C:14]2[O:15][CH2:16][CH2:17][O:18][C:13]=2[CH:12]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1

Participants

Conditions

Temperature: -78 °C

Procedure

A solution of (2,3-dihydro-benzo[1,4]dioxin-6-yl)-carbamic acid benzyl ester (5 g, 17.5 mmol) in dry THF (85 mL) was cooled to −78° C. At this temperature n-BuLi (2.5M solution in hexanes, 14 mL) was added dropwise and the clear solution stirred at −78° C. for 20 min. A solution of E-1,4-dibromobut-2-ene (4.9 g, 23 mmol) in THF (42 mL) was added dropwise and the mixture slowly allowed to warm to rt. The mixture was poured on water and extracted with EA. The combined org. extracts were dried over MgSO4 and concentrated. The product was purified by FC (Hept/EA 9:1, 4:1) and obtained as a greenish oil (2.88 g, 38% yield) which was used as such in the next step despite some contaminations with starting material.

Workup

temperatureto warm to rt
additionThe mixture was poured on water
extractionextracted with EA
dry with materialextracts were dried over MgSO4
concentrationconcentrated
customThe product was purified by FC (Hept/EA 9:1, 4:1)

Sources & evidence

ORD record: ord-46200623fa3147b4ad7a9fcae6d885af
Source dataset: uspto-grants-2012_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08114867B2

Reaction notes

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