Carbon tetrabromide → tert-Butyl (2R)-but-3-yn-2-ylcarbamate

HRID 2403142Notes

Reaction equation

HRID 2403142 reaction equation
C1C=CC(P(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1.C(Br)(Br)(Br)Br.O=C[C@H](NC(=O)OC(C)(C)C)C.Br[C:38](Br)=[CH:39][C@H:40]([NH:42][C:43](=[O:49])[O:44][C:45]([CH3:48])([CH3:47])[CH3:46])[CH3:41].[Li]CCCC>C(Cl)Cl.C1COCC1.[Zn]>[CH3:41][C@@H:40]([NH:42][C:43](=[O:49])[O:44][C:45]([CH3:48])([CH3:47])[CH3:46])[C:39]#[CH:38]

Participants

9

Reactant 5

HCID 11205Carbon tetrabromideHCID 11776TriphenylphosphineHCID 10910049tert-butyl N-((2R)-1-oxopropan-2-yl)carbamateHCID 71464320tert-Butyl [(2R)-4,4-dibromobut-3-en-2-yl]carbamateHCID 178418339Butyllithium

Product 1

HCID 45092359tert-Butyl (2R)-but-3-yn-2-ylcarbamate

Reagents, catalysts & solvents 3

HCID 23994ZincCatalystHCID 6344DichloromethaneSolvent2×HCID 8028TetrahydrofuranSolvent

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) δ4.47 (br s, 1H), 2.24 (s, 1H), 1.49 (s, 9H), 1.27 (s, 3H).

Workup

  1. customthe solvent was evaporated
  2. customto give the crude (R)-tert-butyl 4,4-dibromobut-3-en-2-ylcarbamate
  3. customThe reaction was quenched with water
  4. customthe organic layer was separated
  5. extractionThe aqueous layer was extracted with ethyl acetate
  6. washwashed with water
  7. dry with materialdried over MgSO4
  8. filtrationfiltered
  9. concentrationconcentrated

Sources & evidence

ORD record
ord-8cf29a54689c47b3832b48e89e5d9057
Source dataset
uspto-grants-2014_08
Patent number
US08802657B2

Reaction notes

Loading…